Manufacturing guy-at-large.

Filtering by Tag: DMLS

Stem prints

Added on by Spencer Wright.

Almost a year ago, I posted a rendering of my printed bike stem on my blog here. Now:

These parts were printed by my friends at Playground Global on their 3D Systems DMP320 in titanium 6/4. Like the titanium parts I've had printed (and written about extensively) in the past, these are done via laser metal powder bed fusion - the generic name that often gets referred to as "DMLS". These parts were, of course, designed in nTopology Element Pro; you can see more of my design process here. 

As loyal readers will know, I've put a lot of time into using Abaqus to predict these parts' mechanical properties; more on that in the near future. For the time being, the goal with this print was to test the manufacturing process - and use any lessons here to guide future design iterations. As you'd imagine, there's a *lot* that goes into printing a part that has ~45,000 beams; establishing manufacturing parameters was a good way to filter out nonviable design strategies.

It'll take a bit more work to characterize the as-built design fully, but at first inspection it seems to have been a total success. I was careful to keep most of the beams' orientations at a high angles, thicknesses above .45 mm, and lengths below 3 mm; the result is a structure that's almost completely self supporting.

At this point, the part has been roughly cleaned up and bead blasted to remove any surface discoloration. The next step is to tap the holes, clean up the clamp surfaces, and mock the entire assembly up.

More soon :)

See also: DMLS lattice sample prints, where I describe the part's design a bit more.

DMLS lattice sample prints

Added on by Spencer Wright.

I'm *very* excited about these parts from C&A:

These parts were printed in titanium 6/4 by C&A Tool in Churubusco, Indiana; they were designed in nTopology Element. 

This is a pure lattice structure - the entire geometry is designed as beams and nodes, with no explicitly defined solid regions. The beam lengths are on the order of 2-3 mm; their thicknesses range between .45 mm and 1.1 mm. In some areas (for instance, the bolt holes) this results in a fully solid part, but the transition from lattice to solid is continuous rather than discrete. The result is a structure that's solid where it needs to be and sparse elsewhere, with no stress risers where solid and lattice meet.

The parts are, of course, sample regions of the bike stem that I've been working on for some time now. The intent of the samples was to prove the printability of the structure and identify any potential difficulties. The results were overwhelmingly positive: With the exception of a few small flaws, the parts printed very well, and I believe the problematic areas can be addressed in the design pretty easily.

Given the good quality of the sample prints, I'm planning on printing a full version of the part soon. I'm also experimenting with a few other design variations (intended for a variety of different metal AM machines), and am running them through a beam sizing optimization process with Abaqus and Tosca in order to reduce mass and decrease strain energy. More on these soon :)

Thanks to Rich Stephenson for his ongoing help on this project - and for continuing to educate me on the metal AM industry.

Build process simulation

Added on by Spencer Wright.

Early last year, Andrés Bellés Meseguer reached out to me with a proposition. He had read my piece in Metal AM magazine, and wanted to use my printed parts from DRT Medical Morris to verify a build process simulation workflow that he created using Abaqus. I agreed, and with Dave Bartosik's help I got him the build files necessary to simulate the print.

Andrés' full results were published in a paper titled Prediction of Distortion of a Titanium Bike Part Built by DMLS, which he presented at a NAFEMS conference in November. The simulation used a fine hexahedral mesh at the part itself, and a coarser mesh for the surrounding powder bed and the build platform. At each timestep, heat (representing energy applied by the laser) is applied to nodes throughout the model; it then dissipates throughout the structure. Below, see a thermal map of the part about 70 minutes into the build:

Image courtesy Andrés Bellés Meseguer and Prime Aerostructures

You can also use this simulation to model distortion in the part - seen here at the end of the build:

Image courtesy Andrés Bellés Meseguer and Prime Aerostructures

The distorted areas in the simulation correspond well to the as printed part, but Andrés notes that the magnitude values don't match perfectly; it's likely that some of the discrepancy can be narrowed by adjusting thermal coefficients.

This field - simulating additive processes to predict and compensate for built in stress and distortion - is one that I've been excited about since I began working with AM. Thanks to Andrés for sharing his work - I'm looking forward to more progress on this soon.

Notes on Arcam and SLM

Added on by Spencer Wright.

Yesterday, GE announced that they had put in bids to acquire both Arcam and SLM for a combined total of $1.4B. This move poses some interesting questions about the next few years in industrial AM, and will no doubt have a big impact on both the companies involved and their customers and competitors. I don't have any privileged insight into any of these companies' decision making process, but I have a longstanding interest in the industry and what they're working on. Here are a few observations & questions that occurred to me about the deals and their impact.

Background

In 2012, GE Aviation made three large acquisitions in industrial AM. The first was the combined purchase of Morris Technologies and Rapid Quality Manufacturing, two sister companies based in Cincinnati who had already been a big supplier to GE Aviation (terms of the deal were not disclosed). Later that year, they bought Avio Aero, and Italian parts supplier, for $4.3B. These two purchases showed an interesting balance in technologies. While Morris and Avio had very similar business models (both were job shops that produced parts for GE Aviation and other business units; Avio also produces parts by traditional manufacturing methods), they focused on different additive technologies: Morris on laser, and Avio on EBM.

I've written about the difference between laser and EBM in the past, but a few points here:

  • The fuel nozzle that GE is so famous for printing is made by laser in Auburn, Alabama on EOS machines. I believe that their (lesser known) T25 temperature sensor is made on the same machines.
  • The laser (Note: I'm using "laser" here to refer to processes that are variously called DMLM, SLM, DMLS, lasercusing, and the generic "laser metal powder bed fusion." Note also that SLM can be used to refer both to the printing process AND to the machine manufacturer that GE just acquired.) machine market has a number of providers: Aside from EOS and SLM (the two machine manufacturers that GE is most known for using) there's Renishaw, Concept Laser, Additive Industries, 3D Systems, and a variety of Chinese entrants.
  • While GE Aviation has tended towards EOS machines (see the video above), GE Power & Water uses machines made by SLM in their Greenville, SC plant (Note: Here I'm drawing from an AMUG 2015 and other industry sources; sorry for the lack of a hyperlink reference).
  • Arcam sits apart from these: it's currently the only company making machines for EBM (electron beam melting, or "electron beam metal powder bed fusion" if you're picky).
  • Avio Aero has done some really interesting things with EBM since the GE acquisition. Perhaps most notably, last year they printed low pressure turbine blades out of titanium aluminide, an intermetallic alloy. TiAl has excellent mechanical properties at high temperatures (an important feature of any part that's in the hot stage of a jet engine), and is traditionally cast by companies like Precision Castparts Corp (PCC). Printing in TiAl brings advantages but is extremely difficult due to the material's tendency to fracture. Printing TiAl could be a big deal as GE ramps up production of TiAl blades for the GEnx engine, and it was very interesting to note that after the successful prints, Avio bought an additional ten Arcam systems - the largest purchase that Arcam had ever accepted.

So: GE already had a strong portfolio in additive. What are the implications of the Arcam and SLM acquisitions, and how will this impact the industry?

A full stack, in-house

The most interesting part of the acquisition to me is the fact that GE will now be able to in-house the entire industrial AM supply chain (minus software; more on that below). Previously, they were focused primarily on basic research and applications development (Morris, Avio, CATA, and the Niskayuna Global Research Center) and serial part production (Auburn, Greenville, and Avio). Now, they'll own not one but two machine manufacturers - allowing them to push upstream and make a more direct impact on the development of the additive industry.

But perhaps more importantly, GE gains both powder production (through AP&C, the Canadian powder supplier that Arcam acquired for CAD 35MM in 2014) and final parts manufacturing (through DiSanto, the medical implants manufacturer that Arcam acquired for $18.5M later the same year). When Morris was acquired, they shut down their sales organization and focused on printing parts for internal GE customers. DiSanto is a very different business, though, and I wonder whether it might make sense as part of GE's healthcare unit - with its traditional focus on medical imaging and healthcare IT.

AP&C is a bit of a different beast. They manufacture the raw materials for not only powder bed fusion but also MIM, HIP, and other powder metallurgy applications. Their website advertises commercially pure titanium and ti64, but Arcam also markets cobalt-chrome - which both the fuel nozzle and the T25 sensor housing are made of. I'll be very curious to see whether AP&C continues selling powders to the public, or if they focus on internal use.

Improving - and selling - manufacturing machines

Separate and apart from the implications to GE's internal operations, I'm particularly interested in the way that GE's involvement at these new levels of the tech stack will affect how the industry matures. Try though they may, it's difficult for a company whose bottom line depends on selling machines (as opposed to, say, selling machines AND printing parts, or selling machines AND developing manufacturing software) to truly impact the end-to-end engineering process much. And while GE has been at the forefront of additive research (and, no doubt, collaborates very closely with both their hardware and software providers), I'm hopeful that having them at the helm will push both EBM and laser powder bed fusion forward in a cohesive way. 

Some might suggest that keeping expertise in house would be the strategic choice here, but I disagree. Powder bed fusion today suffers from both a lack of talent (easiest to change by expanding the number of use cases for the process, many of which GE ultimately is not going to compete on) and a lack of process predictability and reliability. GE has more knowledge about improving AM part yield than just about anyone else in the world, but that doesn't mean that there aren't other approaches that they're not trying. Inasmuch as sharing whatever process improvements they come up with will encourage others to try their own approaches, I hope that GE does just that. And they have in the past: through their involvement with standards and industry organizations like America Makes, 3MF, and ASTM F42; through their participation in sessions at AMUG and RAPID, and through their open innovation work (some of which I worked on while at Undercurrent) with GrabCAD and NineSigma.

My hope would be that GE continues to market and improve both SLM and Arcam machines. The latter is particularly dear to me, as EBM equipment isn't currently made by anyone else (and because I've had many parts printed on Arcam machines). SLM is a bit different, as the market for laser powder bed fusion is already so rich. But by that same rationale, the potential impact that any updates to SLM's machines would have could be huge, as they would force other players to respond in kind.

Software

I take GE at their word: They want to be a contemporary engineering company, and they believe that contemporary engineering companies need formidable software capabilities. And if they're going to truly make their mark with a software solution, it would be wise to do so in a realm where they know the problems well.

Even before these acquisitions, GE knew the pain points in additive as well as anyone else. Adding a few machine manufacturers, plus a raw materials supplier and a finished parts manufacturer, will only help that along. So my question is this: Why wouldn't GE make a play in additive manufacturing software? This is, after all, the whole subtext behind the Brilliant Factories initiative: GE knows how hard it is to make things, and they can help you make them better.

As you'll know from my previous writing, I'm excited for advances in build processing (see netfabb and Magics), build simulation (see 3DSim and Pan Computing, and research by Wayne King at LLNL), and in-process monitoring & control (see Sigma Labs, plus the product spec sheets for a *lot* of the current class of laser printers). Each of these is extremely hard in itself, and recreating the entire stack would be extraordinarily complex; I don't expect any one company to solve (or even attempt) them all. But whether they build their own solutions or work with external providers to build them, GE will be a huge stakeholder in the next generation of additive manufacturing software. And if they're serious about being a formidable software company, then why wouldn't they take a shot at building it themselves?

Regardless of how these acquisitions shake out, the next year should be interesting. I'm looking forward to it :)

My writing in Metal Additive Manufacturing Magazine

Added on by Spencer Wright.

I'm extremely proud to say that my writing is featured in the current issue of Metal Additive Manufacturing Magazine. The article summarizes much of my work over the past two years, and includes many of my thoughts about how the industry can be better in the future. You can read the full article here.

Thanks so much to Nick Williams and the rest of the Metal AM for asking me to contribute!

DMLS vs EBM titanium parts

Added on by Spencer Wright.

Note: Below, I use the term "DMLS" to refer to laser metal powder bed fusion. Some will have issues with this usage; I encourage readers to ignore the (possibly trademarked) terms themselves and focus on the information contained within them.

Over the past few months I've spent a lot of time trying to determine whether DMLS or EBM would be a more suitable technology for the titanium bike parts I'm working on. Early on (in my collaborations with DRT and Layerwise) I focused on DMLS, and more recently I've worked with Addaero on EBM. These two technologies are in many ways complementary, and in truth I expect to work with both of them - but their design constraints and total manufacturing process chain are a bit different, and I wanted to spend some time understanding how that will affect the cost and quality of the parts I'm working on.

In the video below, I show some of the basic differences in surface quality and support structures. Of course there are many other factors that are worth exploration, starting with minimum feature size and built-in stress, probably; I'll get to those in future updates.

This video gives an overview of the differences between DMLS and EBM titanium parts. I show basic surface finish characteristics, support structures, and support removal.

Incidentally, I'm *really* interested to see the differences between DMLS and EBM in printing the lattice structures I've been working on. More soon :)

Notes on Magics

Added on by Spencer Wright.

This month I'm doing a deep evaluation of Materialise Magics 19 and SG+, and trying to understand both the major features of the software and the philosophical perspective that Materialise views additive manufacturing through. I'll post more thoughts on the overall process chain later, but for now I wanted to work through some of the observations I've had in my first encounters with Magics.

For background: The cost of this software is in the neighborhood of $20,000. It's generally NOT purchased by people who don't themselves own industrial (i.e. $250k+) 3D printers. But I feel very strongly that without some knowledge of how it works, independent designers will be doomed to creating inefficient, difficult to manufacture designs. So, I signed myself up for a 30 day demo and got working :)

Note: Throughout this post, I'll be showing screenshots of my titanium seatpost part. I've already had one of these parts EBM printed by Addaero, and expect to have versions of it printed in both EBM and laser metal powder bed fusion (which I'll refer to as "DMLS" throughout this post) in the near future. In order to simplify the descriptions below, here's a key to the part's features:

My part's nomenclature.

Overview

I believe Magics to be a classic example of a piece of industrial software whose development has been driven by customers who are large, powerful, and often have divergent interests. 

In many ways its functionality probably benefits as a result. Materialise has close relationships with a number of industrial 3D printing machine manufacturers (notably Renishaw, SLM, and EOS, all of whom have agreements in place to allow Materialise access to their machines' build parameters, and develop build processors to work natively on those machines). They also collaborate closely with many of the large manufacturers (both OEMs and service bureaus) who build 3D print parts on the machines that Magics supports. Through these relationships (and through their own internal parts business), Materialise can get an up close view of what their biggest users need out of the software, and prioritize their efforts accordingly.

On the other hand, by relying heavily on key accounts to drive the product's development, Materialise gives up much in the way of product vision - accepting, instead, a steady stream of feature creep. Every additional feature (while I'm sure they're all valuable) makes the entire application more difficult and clunky to use, and it often feels like Materialise has given two different customers two distinct ways of doing the same thing - simply because each one demanded that the workflow fit their way of working. This kind of path is ubiquitous around the world of industrial software, and Materialise is, to be fair, ultimately at the whim of its (enormous) industrial stakeholders. But as someone coming in from the outside, the result feels schizophrenic.

The core issue is that independent designers like myself are seen as customers, while Magics' development is driven by client relationships. Again, this isn't Materialise's fault, and nor is it ipso facto bad. But I don't believe that the incentive structures that drive Magics' development are optimal for the industrialization of additive manufacturing, either. I'll explore this topic more in a later post; for now, just ponder this. In the meantime, here are my initial observations of how this big, important, and powerful piece of software works.

One important note: Materialise is a member of the 3MF consortium, which is working to create a file format which apparently contains "the complete model information" within "a single archive." My hope is that 3MF allows for more of the process chain to be accessible from a single interface, and that Materialise is a key part of that development. I'm looking forward to learning more about 3MF in the near future; stay tuned for more.

UI

Magics has two or three ways to do basically everything. At the top of the window is a drop down menu bar. It changes depending on context, but generally has a lot of functionality; in the default view, it has eleven menus - a mix of standard stuff (File/Edit etc) and context dependent stuff (Fixing/Scenes etc).

Directly below that is a tool bar, which mostly contains standard tools (undo/redo, Print 2D, Zoom/Pan/Rotate, etc). As far as I can tell, every command in the tool bar is also accessible via the menu bar AND via keystrokes & mouse gestures.

To the right of the tool bar is a series of tabs, which toggle the appearance of another tool bar below. These are a bit more context dependent, and as far as I can tell the correspond 1:1 with what's shown in the "Tools" drop down menu above. Most of these functions, though, *can't* be accessed by keystrokes or mouse gestures.

Overall, Magics' multiple, competing UIs are not unlike most of what's out there in industrial & B2B software today. Most companies (including Materialise) tend to bill this as a feature: the user can interact with the software in a wide variety of ways (keystrokes, mouse gestures, drop down menus, or toolbars), so almost anyone will be able to get comfortable with the interface quickly.

Personally, I prefer opinionated UIs in industrial/B2B software. The best one I'm aware of is McMaster-Carr's, which is built specifically for MRO professionals and makes everyone else adjust their mindset to that of someone looking for replacement parts. I'm not an MRO professional, but once you figure out how they work, the experience is wonderful. 

Magics doesn't act this way, though. The UI doesn't guide me at all; it simply offers a multitude of options, and lets me decide which one I prefer.

Orientation

Magics' "Orientation Optimizer" is very straightforward, and seems in some cases like it'd be useful. I used it only briefly, but to be honest I had already decided more or less the orientation I wanted the part to be printed in. As it happens, the Orientation Optimizer confirmed my plan, but I take that confirmation to be a bit of a false positive. As I discuss below (and have written about extensively in the past), setting an orientation angle really requires an understanding of the part's design intent and manufacturing life cycle, and Magics lacks these. As a result, it can only optimize for the factors that it understands: in this case, some combination of Z-height, XY projection, Support Surface, and Max XY Section. I chose the middle two of these, and Magics gave me exactly what I already knew I wanted.

The orientation that Magics suggested for my part

This tool is probably more useful in high mix environments (service bureaus), but most of the people in the industry I've spoken to say that when they use it, it's just as a starting point; the final orientation is almost always set by a human being.

Support generation

Generating support structures in Magics is really straightforward; it's possible (though almost definitely not ideal) to simply choose a machine, plop a part on the build plate, and hit "generate support." Magics has some understanding of the technology you're using (in my case, either EBM or DMLS), and it creates support geometries that are (reasonably well) tuned for the process. 

But before you even get that far, Magics has a nice feature that allows you to preview which surfaces will need to be supported - the "Supported area preview." Presumably this would be used while the operator is setting the part's orientation in the build chamber. It allows you to view downfacing edges as shaded, and it shades them on a color gradient depending on what you want to see. Here I'm looking at the underside of the part, and varying the angle that Magics highlights:

On my part and in this orientation, there are two large areas that need support structures (inside the saddle clamp cylinder, and from the shoulder straps down to the build platform). But if you look closely, you can see that there are also a series of tiny areas with downward facing surfaces:

  • At the v-necks, there's an surface below 30˚ whose area is .91mm^2. If you change the selection angle to 50˚, the area grows to 2.58mm^2.
  • At the window tips, there are surfaces with 30˚ whose areas are about (they vary slightly from window to window) .22mm^2. If you change the selection angle to 50˚, the areas grow to about .73mm^2.

For comparison, the cross sectional area of a "medium" grain of sand (as described by ISO 14688) is about .4mm^2. Which is to say that these are relatively small surfaces. My hope is that even though they face downwards, they won't require support structures at all.

When you enter the support generation module and hit "generate support," Magics simply looks at the faces that face downward, chooses a support type that's appropriate for the surface size & shape, and projects that support directly downward. Here are the automatically generated supports for both my part in EBM and DMLS:

Throughout Magics' UI, there are "tool pages" on the right of the window that offer a variety of context dependent functions. When you're in the support generation module, there's a section of "Support Pages" there that let you analyze and modify the support structures in your build. Looking at the support pages in the pictures above, you'll notice that I've got the "Support List" page open, and that there are 12 supports listed in that view. For each of these, a variety of data is displayed: ID; type of support; some basic geometrical data, and an "On Part" column. You'll also notice that the supports that are "On Part" are keyed red in the list. This is a very useful piece of information: those supports, when they were projected downwards, ended up falling onto the part itself. The result is that when the part is printed, those supports will tend to be more difficult to remove. In the case of the MLab build above, supports 3 and 4 run the full inner diameter of the saddle clamp cylinder. In the Arcam A2X build, supports 3 and 4 are in the same situation - but a whole series of point supports (7-12) are also partly trapped in the part's windows.

In my experience, this is *not* desirable. Especially with EBM, supports that fall onto the part itself are a real pain in the ass to chip out (for a bit of context, see the photos I took of the first parts I had EBM printed). In addition, they tend to make the surface they're hitting rough, and as a result the part often requires more post processing.

In order to avoid this, I need to modify the support parameters. By going into the "Advanced" section of the Support Parameters Pages and checking off "Angled supports," I can pull the two big Block supports (ID 3 and 4) away from the part:

(I'm working on similar edits to the EBM build, but want to get a little clarification from Arcam on those point supports first.)

I can do a variety of other things to these supports, including "Rescale platform projection," which essentially flares the support in/out as it goes down to the platform. There are also a slew of parameters (hatching, hatching teeth, teeth synchronization, perforations, etc) which seem mostly designed to make the supports easier to remove from the part. All of these can be preset in the Machine Properties screen (which, frustratingly, isn't accessible when you're in Support Generation mode) or adjusted on a support-by-support basis from the "advanced" tool pages.

To be sure, I'm only scratching the surface on Magics' support generation features here. Magics will let you play with a *ton* of support parameters. I get the impression that there's a lot of nuance here, and that there are many parameters that you'd only play with in edge case builds. Regardless, the number of possibilities generated by varying just a few of the options is staggering; in order to know how they affect part quality, you'd need to run thousands upon thousands of test builds.

Eventually, it's very likely that Magics (or whatever replaces it) will have thermal & residual stress simulations built right into the software. Today, however, machine operators have remarkably little info about the finished part before they actually print it. Except...

Build time estimation

This is a key part of the additive design-for-manufacturing process. Knowing how long a part will take to print is a *huge* factor in what it costs, and is critical in comparing two build configurations for the same part.

Magics has a build time estimator, but it's not plug-and-play. Instead of shipping pre-loaded with estimates of how long a given machine will take to build a part, Magics requires the user to run "Learning Platforms" - and you need to own your own machine to do that. And, of course, I don't own a metal powder bed fusion machine.

I was *really* excited to get a build time estimation, but no dice.

The reason for this is that in order to estimate build time, you need to know how both the slicer and scanning strategy work - as well as mechanical factors like scanning speed and recoating time. And while certain machine manufacturers (see below) share this information with Materialise, for many it simply isn't worth it. They see those process parameters as valuable, and don't see the benefit of sharing that data with a third party software developer. Moreover, most of them can provide very accurate build time estimations in their own software, and the manufacturing engineers that use the machines take it as given that they need to use that at some point in the process anyway.

This strikes me as a big failing. Magics needs a way of sharing data about their builds: a public repository of machine parameters and build times. Without that - or without, on the other hand, convincing the machine manufacturers to share that data themselves - Magics is left with a huge disconnect between the build setup and the end product. This undercuts Magics' claim to be "The link between your CAD file and the printed part." If it lacks basic data on build speed for the most common machines in the industry, what exactly is it linking to?

So: As of the time I'm writing this, I've got emails out to a handful of the biggest metal powder bed fusion machine manufacturers in the industry, asking for Magics learning platforms. If anyone out there can share that data with me, please send me a note!

Build Processors

My demo doesn't include these, but they're worth touching on. For a few big machine manufacturers (Renishaw, SLM, and EOS), Materialise has developed build processors that are tuned to those machines' capabilities and specifications. Presumably, these companies provide Materialise with in-depth data about how their machines work, some of which is either patented or proprietary. Materialise then builds software modules that, through a few intermediate steps (the most notable of which are slicing and subdividing/hatching), produce a job file that can go directly to a machine.

Materialise bills the build processors as reducing complexity in the manufacturing life cycle, and allowing both Materialise and the machine manufacturers "to focus on their core competencies." Having not played with them myself, I can't really comment. I hope to learn more soon.

A few things Magics *can't* do

To reiterate: It's my impression that Materialise built Magics to fill a really big hole in the existing work chain, and the bottom line is that that work chain is something that no single party (let alone Materialise) created. It's also, in my opinion, *not* the right work chain for the future of additive manufacturing, and Magics' role in it highlights a lot of the problems in the industry today. Here are a few things that I noticed that Magics can't, for various obscure and not-so-obscure reasons (many of which are decidedly *not* Materialise's fault), do.

Understand the underlying design

This is something I've touched on in previous posts, but it struck me again when I was in the "supported area preview" screen. It's *very* likely that I could, with a relatively small amount of work, edit the underlying geometry in order to reduce the number of supports needed significantly. But I'm not aware of a way of showing downfacing regions in solid modeling software (Solidworks/Inventor, etc), and it's rather cumbersome to bounce back and forth between Magics and Inventor to try to optimize the design for additive. 

All across the industry today, I hear people talk about design software that understands the intent of the designer, and responds to accommodate it. This may be feasible in the near future, but the bottom line is that Magics (as it stands now) is *not* part of that process chain. Once a designer transitions from parametric modeling to surface tessellations, all of the geometry data is lost. If manufacturability feedback (like the supported area preview screen) is provided in software that reads surface tessellations (as Magics does), then going back to edit the underlying parametric model is *always* going to be cumbersome - and necessary.

Understand/display surface quality issues due to orientation

In all additive processes that I'm aware of, surface finish will vary significantly depending on the orientation of a surface relative to the build direction. Given the layer thickness of the printed part, this is relatively straightforward to simulate - not to a high degree of precision, but with a good amount of accuracy, at least. Magics doesn't do this, and it leaves me feeling like I'm missing a key piece of information about the printed part. Sure, I can imagine what the part will look like if I just think about it for a minute, but it does strike me that having some indication of areas with high stepover (which will occur wherever a surface is oriented close to the XY plane) would be really helpful - and not particularly hard to implement (caveat: everything I said above about feature creep, etc).

Understand the place of additive in the process chain

This may seem like I'm splitting hairs, but I think it's worth reiterating: Magics bills itself as "The link between your CAD file and the printed part." It is NOT concerned with the end product, which in almost all cases will have additional (subtractive) processes performed on it.

Why does this matter? When I had this part EBM printed recently, both the saddle clamp cylinder and the seatpost cylinder came out undersized. I know now that one of two things needs to happen there: either I need to compensate for the printing process in the underlying model (by making the designed dimension larger than I actually want it to be), or I need to remove material from the as-printed part (by machining, grinding, or similar).

Magics doesn't know any of this. If it did, it might be able to give me intelligent advice on what surfaces to take extra care with - and which I should ignore, as they'll be machined away in the end regardless.

In the end, Magics is a piece of CAM software - but it only deals with one step in the production chain. Changing this is a monstrous, complex task, but it's one whose impact will be hugely positive.

So

Magics is pretty cool - it does a *ton* of really useful stuff. You'll note, also, that I'm basically not interested at all in its "fix" feature, which (I'm told) is used a lot with models that come out of Rhino.

But it's also representative of a lot of what's going on in industrial additive manufacturing today. This isn't Materialise's fault; it's just the way things evolved, and is the result of (I'm sure) a lot of collaboration, competition, and plain old hustling (all of which I fully support) in the industry over the past few decades.

Regardless, Magics is a place where you can see a lot of the implicit assumptions that industrial additive manufacturing has been built upon. More on this soon.

Improved laser build

Added on by Spencer Wright.

Learning new software is fun. This is me after a few hours playing with Materialise Magics 19 and SG+.

I've made a few modifications to the standard build:

  • Changed the surface selection angle to 50°. This build is set up for laser metal powder bed fusion (aka DMLS), which will print angles a bit below that, and it's very possible that 50° isn't optimal.
  • Changed the upper supports so that they're angled. In my last post you'll notice that if these are vertical, they'll rest on the bottom face of the cylinder. While that may be fine structurally, it means that I'd have that much more to clean up, and I think I'd rather have the supports go all the way down to the build plate instead. It's *possible* that this will reduce the amount of post processing necessary on the part - you'd need to run multiple builds with different configurations to be sure.

It's worth noting that this part is too far off the build plate right now - I'm still trying to get used to Magics' UI, and figured it didn't matter for now. I should probably also orient the part at a slight angle from vertical (see my recent post, here, for more details on this); again, I'll play with that a bit more later.

Oh, and I probably want to add additional reinforcements to the short ID, to make sure that it prints round. I'm looking at a few methods of doing this, most of which would require some work back in solid CAD (Inventor), or *possibly* some volumetric mesh generation software (like nTopology). 

I'm definitely still getting used to Magics' philosophical perspective on the additive process chain, too. I have some thoughts on what this is, but will play around more before I share them :)

Stay tuned.

This week: Materialise Magics 19 and SG+

Added on by Spencer Wright.

Just a little teaser:

This week, in addition to the networking I'm doing (remember: I'm a free agent now, and directing my efforts toward finding the best path for myself in metal additive manufacturing), I'll be diving deep into Materialise Magics 19, the industry standard software for metal 3D printing build processing. I'm excited to learn more about its capabilities, and will share more later this week. I'll be spending most of my time working on orientations & support structures schemes for my titanium seatpost head, seen here in Magics' simulation of an EOS M280:

Magics bills itself as "The link between your CAD file and the printed part." It's used by OEMs and service bureaus alike to prepare design files to be printed - often times on the very machines that I've been building parts on (one, two) over the past year. In most cases, Magics imports an STL file. It then can be used for three big chunks of work:

  1. Fixing. In many cases the files that you import are broken in some way (edges not connected; faces oriented in the wrong direction), and can't be printed as is. Magics has a suite of tools that analyze and solve these problems.
  2. Editing. There are a variety of reasons why you'd want to edit a design before printing it, but probably the most common is that it won't fit in the build chamber of the machine it's being printed on. Magics offers tools that cut, hollow, thicken, perforate, extrude, label, boolean, and support parts and their features.
  3. Build prep. This is the part that I'm most interested in, as it directly affect the workflow that I've beed dealing with on my titanium parts. Here, the user selects the machine that the parts will be printed on. Then the parts are oriented physically within the build chamber, and an analysis is run to confirm that there are no part collisions that will affect the build.

Lastly - and of particular interest - is the SG+ module for support generation in metals. This would fall somewhere between (and across) numbers 3 and 4 above, and involves creating solid and mesh support structures that anchor the part to the build plate and provide thermal sinks to ensure a successful build. The SG+ module is a critical part of the metal 3D printing process chain today. It's used extensively across the industry, and engineers who are skilled at support generation are highly prized.

This week I'll be exploring these features (especially build prep and SG+) extensively; stay tuned for updates.

3D printing titanium: Learning to learn from success

Added on by Spencer Wright.

Dear reader — 

This report is an update to my experiences in metal 3D printing; it describes a good chunk of what I’ve been working on over the past four months. While I’d like to say that it stands on its own, I think there’s some context — especially if you’re just beginning to explore metal 3D printing — that can be gained from reading my earlier posts (starting with my long "Bin of broken dreams post") first.

For background: I believe that functional, engineered consumer products made by additive manufacturing are an inevitability. In order to prepare myself for that inevitability, I’ve been developing a line of bicycle parts made by metal powder bed fusion, a process that’s used extensively in aerospace, medical, and tooling applications. My last post described the difficulty and constraints I’ve experienced in part geometry and build orientation. Since then I’ve turned a corner, and today I can say that I’ve successfully designed, built, and tested a functional product — which at last puts me in the position of needing to learn from success.

As I’ve documented the process — and frustrations — of developing metal 3D printed parts, I’ve been pleased and surprised at the number of people who’ve reached out to me to commiserate (n.b., if you’re reading this and want to do so yourself, please drop me a line). Without exception, they have expressed solidarity. “We share all of your frustrations,” one person said. “I have been through the same pain as you,” said another. 

One of these people was Tom De Bruyne, General Manager at Layerwise. Layerwise is a Belgian company which was started out of the Catholic University of Leuven (one of the premier centers of additive manufacturing research); it was acquired by 3D Systems in late 2014. They’re famous for being one of the few service providers who built their own laser metal powder bed fusion machines, and have a ton of experience making 3D printed parts at both prototype and production scale. We struck up a conversation, and soon agreed to work together.

While popular opinion would have you think that quantity is a non-factor with 3D printing, the realities of running a service bureau are much to the contrary. To job shops, quantity is a critical factor; if a part will be produced at large volumes, every detail of its design and manufacturing life cycle must be examined. If, on the other hand, you’re printing a tool — or a prototype of a part that will be manufactured conventionally — then most shops will focus on getting the first print right without modifying its underlying geometry.

My project falls somewhere in the middle: while my design is certainly imperfect, there are many aspects of it which are very close. Moreover, it poses challenges (most notably its opposing cylinders, oriented 90° apart, and also its thin-wall construction and bolt boss) that will exist throughout any redesign, and solving them now will only improve my ability to deal with them in future iterations. 

At the current juncture, the key questions to test are:

  • Can we reliably build my current design with minimal post processing?
  • Does my current design meet the necessary performance standards (strength, security, etc.) for bicycle seatmast toppers?

In practical terms, the first question boils down to whether we can build a part that can be installed on a bicycle. This means two things: maintaining inner diameters which are round and dimensionally accurate to within +/-.006", and having a bolt boss on the long cylinder which, when tightened, is capable of securing the part to a bicycle’s seatmast.

My last prototype was built on its side, and the long cylinder’s aft wall distorted as it was sintered. We added a series of solid ribs in order to counteract the built-in stress in that wall, but it ended up like a game of whack-a-mole: each reinforcement just moved the stress somewhere else. A new approach was needed.

Unlike most of the US job shops I’ve spoken to, Layerwise bundles together many low-volume customer orders into each build; my part was printed alongside a handful of other titanium parts in one of the 15–20 machines that Layerwise designed and built themselves. This means that Layerwise is able to process a large value of parts at once, even if they’re only building prototype quantities of each design.

This poses a significant challenge: if one part fails, it can jeopardize many customers’ orders. To mitigate this risk, Layerwise constantly monitors a slew of process signatures, and can adjust machine parameters on-the-fly if they detect problems. They’re also working on a layer-based deposition control & verification system (the details of this are secretive, but it sounds similar to the optical tomography systems that other machine manufacturers are working on today). Still, each part is evaluated carefully beforehand in order to anticipate and avoid failures. Especially for short-run prototypes, it’s usually better to over engineer the support structures (and ensure a successful build) than skimp out and need to rebuild the part later.

Layerwise is secretive about their custom-built machines, but they did tell me a few details. They each contain a single laser, and are built around roughly the same form factor (275mm x 275mm x 420mm) as most of the industrial machines on the market today. I also understand that Layerwise uses a recoater blade (unlike 3D Systems’ ProX line, which uses a roller), though I couldn’t confirm whether it’s a hard material (like the high speed steel blades that most EOS machines use) or a soft one (like the polymer wipers often used on Concept Laser machines). They’re able to print in about 15 materials, with the majority of their work being done in titanium. They monitor temperature, pressure, and oxygen content on-the-fly, and are working on additional variables — including full melt pool analysis.

Layerwise has in-house wire EDM, and has a daughter company that does 5-axis CNC machining. But most prototype parts, including mine, are finished by hand. When validating a part for production, Layerwise tests the full manufacturing lifecycle, building multiple full batches of parts and sending them out to be post processed. Once they’ve validated the process, they will in some cases hand off production to other 3D Systems divisions.

Reorienting

I worked with Martijn Vanloffelt, a project engineer at Layerwise, to prepare my part to be built. He used a few key tricks:

In order to maintain roundness in the saddle clamp cylinder (the shorter of the two cylinders, which was was going to be oriented more or less parallel to the build plate), Layerwise reinforced the inner diameter with three serrated discs. 

They also oriented the part slightly off-axis in both the X and Y axes. This brings me to a point that’s worth highlighting: In metal powder bed fusion, a part’s orientation has a number of effects. First of all, any surface with an angle of less than about 45° (depending on material) must be supported. As a result, it’s generally better to orient a part so that all overhangs are as steep as possible.

From NIST Technical Note 1801, a good primer on laser metal powder bed fusion.

But in addition, one must consider the angle between the part and the recoater blade. If the part lifts up at any point during the build, the recoater blade will strike it. The longer the area of contact is, the worse the result will be. Some machine manufacturers offer alternative recoaters to lower this risk (3D Systems ProX uses a roller; EOS offers a carbon fiber brush; Arcam uses a metal comb; and both Concept Laser and SLM offer soft polymer blades), but most use a piece of high speed steel (or, in the case of older EOS machines, a ceramic blade) to spread powder across the build platform. Regardless, it is usually better to orient parts slightly off axis in the XY plane, so that the blade doesn’t contact the part’s walls all at once. 

Orienting parts off axis can also help improve surface finish. When a cylinder’s axis is aligned in the XY plane, the top face will exhibit an undesirable stepped appearance; my earlier prototypes all had this feature. When a part is oriented off axis, the surface finish is generally more consistent.

I should note that none of these techniques is guaranteed to work in all cases. Layerwise has a lot of experience building a wide variety of geometries, and has developed a sense of how to anticipate and deal with issues as they come up. I got the impression that the techniques they used on my part are things they’ve used in the past, but each design is different — and even a tried-and-true method of dealing with one design isn’t guaranteed to work well on another.

The Layerwise team also put a lot of care into generating mesh supports. Like most of the additive metal industry, Layerwise uses Materialise Magics for their final build prep, and they’ve developed expertise in exploiting the software in creative ways. I’m not able to share a detailed description of the supports Layerwise created for my part, but I can say (and anyone in the industry could confirm) that they were needed in four areas:

  1. Underneath the part to anchor it to the build plate. 
  2. Inside the saddle clamp cylinder. 
  3. Inside the window in the center funnel area. 
  4. Inside the seatmast clamp bolt boss. 

Layerwise took great care to orient the part such that it didn’t require support structures inside the hidden voids in its center section. This is something that designers and project engineers alike need to think about as a part heads into production. Not only can powder bed fusion not make fully sealed voids (if you printed a sealed sphere, the entire center would be full of trapped, unmelted powder at the end of the process), but many geometries will require support structures in areas where they’re difficult or impossible to remove. For instance, a Klein bottle could be printed in metal — but no matter how you oriented it, there would likely always be support structures stuck inside its fat end. Because of the angles in my part, it was possible to avoid this — but a different design might not fare as well.

The Parts

The first part Martijn printed was a big step forward: The build completed successfully without collapsing. However, a new problem arose. The windows on the seatmast clamp area caused the two “leaves” of that cylinder to twist as they were built. By the time the window closed back up, they had become misaligned, and a witness was clearly visible where they joined back together. The part had a clear flaw — and it wouldn’t be acceptable for production.

In the next build, Martijn added a curved, perforated disc to each of the seat mast cylinder’s windows, keeping them aligned as they grew. The part that resulted was a full success, printing with clean, smooth surfaces and good near net dimensions.

Layerwise’s second build.

Considering how much support material needed to be added back into the seatmast clamp area just to get it to build properly, I’m struck again with how inefficient my design is. The windows in the sides of the part are meant to reduce both weight and cost, but a bunch of energy is put into supporting them — and then cleaning the temporary supports out again. Instead of windows, I could just as well have replaced the walls with a lattice structure that would both decrease mass and be self-supporting during the build process, bringing the part’s cost down.

This hammers home a point that has plagued my design process: Without knowing — and, optimally, having input into — how a part is going to be oriented and supported during its build, designers are doomed to creating inefficient designs. Designing for manufacturing requires an intimate knowledge of the manufacturing process, including direct access to detailed information about how the part will be oriented and supported. But in most designer/service provider relationships today, that information comes well after many of the important design decisions have been made — if it comes at all. As a result, it often takes a large investment (both in time and money) just to prove whether additive can possibly be used to create the part at hand — and once that’s been proven, many additional iterations are sure to be needed.

This is a key problem in today’s additive manufacturing supply chain: while parts are usually designed in a solid modeling environment (often Autodesk Inventor or Solidworks, each of which cost between $5–10,000), builds are oriented and supported in Materialise Magics — which costs an additional ~$20,000. As a result, independent designers are stuck with a disjointed process, which requires costly iterations and lots of communication with the service bureau who’s preparing the part to be built.

Regardless: At this point in the process, it didn’t make sense to redesign the seatmast clamp area to reduce supports. Martijn’s build had a very high likelihood of completing successfully, and it was time to put it to the test.

It worked.

Post processing 

After printing it, Layerwise did a bunch of post processing before sending the part to me:

  1. First, the entire build plate was stress relieved. Layerwise’s stress relief process is proprietary, but a typical process would involve putting the build plate in a furnace and bringing it to 600°C over a period of an hour, then holding it there for three hours before turning it off. In theory the furnace is either argon purged or vacuumed, but in practice it may contain small amounts of oxygen too. Layerwise says that the vast majority of the stress relief that they do is performed in a vacuum, but argon is typically used on prototype parts.
  2. Then the parts were removed from the build plate. Like most shops I’ve spoken to, Layerwise uses wire EDM — though bandsaws are also common.
  3. At this point, each customer’s part is separated and processed on its own. Supports are removed by a totally unsexy manual process, often involving wrenches, picks, and mallets.
  4. Where support structures have been removed additional cleanup is usually necessary. On prototype parts, Layerwise makes extensive use of rotary grinding bits.
  5. The inner diameters of my part were both ground to their final size. Layerwise told me that this process was 100% manual, and I was blown away at the precision and consistency of the surface finish.
  6. Then, any remaining features were micro shot peened with a nonabrasive ceramic medium.

At this point, Layerwise sent me the part. Still to be done, however, was to tap the female threads in the seatmast bolt boss.

Herein lies an important point: metal 3d printing does not, in general, produce usable mechanical features like threading. In conventional manufacturing, threading is often just another step on the same machine: mills and lathes can both easily create female threads. But with additive, threading almost always requires secondary processing. As a result, the design files that are loaded into Magics only contain plain-bore thru holes; any threading specifications must be documented (and manufactured) separately.

So, the part that I received simply had a 4.2mm hole in it; it was up to me to cut the M5 female threads. “No problem,” I thought. I’ve got a tap handle right at my desk, and am more than comfortable using it. 

At this point, I became painfully aware of what’s called alpha case. Alpha case is a very hard, brittle layer of oxygen rich titanium in a part’s surface (for an interesting study on alpha case depth, see this); it’s the result of the titanium having been processed at high temperatures in environments where oxygen is present. And as I tapped the hole in the first part that Layerwise printed me, I realized that it’s very, very difficult to cut.

In order to make my job easier, I purchased a set of custom progressive taps from Widell Industries. Progressive taps cut threads in three steps, increasing the thread depth as they go. As a result, the cutting force required is generally much lower.

Even using progressive taps, I was shocked at how difficult tapping the second part was. It was incredibly slow going, and produced a lot of heat. I used cutting fluid liberally, and 45 minutes later was done.

I should note here that titanium is a hard metal regardless of how it’s processed. Moreover, alpha case is preventable; in this case, it’s simply the result of the stress relief process being done in a furnace that contains some trace oxygen. Annealed titanium 6/4 has a typical Vickers hardness of about 349, but when a part has been stress relieved in an oxygenated environment, that number might jump to more than 412. By comparison, 4130 steel and 6061-T6 aluminum (both of which are used extensively in the bicycle industry) have Vickers hardnesses of around 207 and 107, respectively. In future prototypes, I would probably specify that the stress relief should happen in a full vacuum; that would at least make the tapping a bit easier.

Regardless: Finally, the part was ready to assemble:

After a total of eight build iterations, I could finally have the part tested — and learn whether my underlying design worked.

Testing

To help understand if my design would handle real world performance requirements, I worked with EFBE Prüftechnik, a German bicycle & component testing facility. EFBE tested the part to ISO 4210–9:2014, 4.5. That test entails:

  1. Clamping the seatmast topper onto a 34.8mm pillar angled at 73°, and fitting a dummy saddle rail into the saddle clamp.
  2. Applying 100,000 cycles of a test force of 1230 N, at a distance of 70mm to the center of the rail clamp, with the saddle rail tilted down/backwards by 10°.
  3. Applying a vertical static load of 2050 N to the center of the saddle rail clamp.

Marcus Schröder, managing director of EFBE, put my part through the dynamic test first. It passed.

Before he went through the static load test, Marcus asked whether I wanted to make sure I got an intact part back — or if I would rather find the failure mode in the static test. In the latter scenario, he would apply the maximum force his rig could handle and see if he could get the part to break — allowing me to redesign it accordingly. Wanting to know as much about my design as possible, I chose the latter option.

Marcus’s test fixture was capable of applying 3750 Newtons to the part. My part withstood the whole thing.

So.

Marcus used penetrating dye to confirm that the part didn’t have any micro fractures, and it came back negative. The part had met and exceeded the requirements for parts like it.

My part, covered in penetrating dye after being tested.

It’s worth noting that this test is simply that: a test. It’s meant to simulate real world conditions and guarantee that the part meets generally accepted standards. But it simulates those conditions only generally; manufacturers of these kinds of parts will often have their own in-house spec that to tune the characteristics they optimize for. But in general, a designer needs to choose a test, and then optimize his design such that the part fails just beyond the test’s requirements. If I trust the ISO spec implicitly then it stands to reason that I should remove more material from the part; after all, it passed the test with a wide margin.

Regardless, my part could be further optimized. What I’ve done to date was prove a basic concept: That metal powder bed fusion can be used to make thin walled bicycle parts. Which, to be honest, isn’t a particularly surprising result; after all, metal powder bed fusion has been used by others to create all kinds of bike parts, including both road and mountain frames. 

The question is: Can I make it commercially viable?

Practical matters

With the current design and an order quantity of 10 pieces, the as-printed parts cost about $500 to make. Meanwhile, the most expensive commercially available seatmast topper I’m aware of (made by No22) costs $300, and the fanciest seatpost I’ve ever seen (made by AX Lightness) was under $600.

Now, there are a number of interesting things to note here. First, I’m able to buy in fairly low quantities. It’s not unreasonable for me to purchase parts in batches of 10, which is about as low as any non-stock commercial product in the world— and much lower than most products that involve forging, casting or CNC machining. If I can sell my part at a high end price point, then it wouldn’t take much cost reduction before I’ve got a reasonable margin — even with a strikingly low order volume. And there are a number of ways that I can reduce cost on this part:

  1. Even keeping the part’s design the same, I can reduce the cost by 25–40% by doubling the layer thickness. This will result in a rougher surface finish, but it’s possible that the difference will be acceptable.
  2. A significant amount of time and effort can be saved by redesigning the underlying model so that the inner diameters need very little — or even zero — post processing. It’s unclear exactly how much work this will take, but it could reduce the price significantly.
  3. Moreover, the entire part can be redesigned in order to reduce both the end mass *and* the amount of support structures necessary. Both of these have a big effect on price, though it will be time consuming to find an optimal design.

All of this assumes that I stick with a laser powered process. Electron beam melting (which I’ve been experimenting with) might reduce cost further, though the design constraints there are quite different. 

It’s also possible that while this part isn’t the absolute best application for additive manufacturing, there’s another place on high end bicycles where additive works better. This is key: The cost of this part is in the right order of magnitude as my goal. Any number of small changes — whether to the machine’s build parameters, the design, or the underlying cost of the technology — could easily put the numbers in my favor.

Industry observations

As I hope you would expect by now, a few things have jumped out to me in this past few months of work — some relating to longer term questions I have about the industry.

Manufacturing design

As a designer, having more — and earlier — access to support structure generation software is incredibly helpful. Today, countless design decisions are made on little more than a hunch; it’s not until much later that the ramifications of those decisions become evident. This leads to an inefficient design-for-manufacturing process, where it’s difficult for product designers and manufacturing engineers to communicate all of the nuance needed. Until professional grade design software (and here I’m looking at Autodesk, Dassault, Siemens, and PTC) allows these implications to be understood early on, this will be a big problem. In other words, I should be able to set build orientation and design support structures directly in my CAD modeling environment.

Documentation

The designs that are loaded onto a metal 3D printer are often very different from the finished part, whether due to the addition of stock material to be removed subsequently (like my female threads), or the support structures necessary to hold the part on the build platform. But today’s modeling software generally only shows one state for each 3D model; those intermediate, near net shapes aren’t linked to the end design. This makes the design for manufacturing process even more disjointed and awkward, as it means that I’m never working on the same design documents as my manufacturing partner is. This communication structure is bound (cf. Conway’s Law) to be replicated in the end product, and the result is bad. To fix it, we need a new class of software that blends CAD (computer aided design) and CAM (computer aided manufacturing), allowing designers to understand a part’s production cycle with perfect clarity.

True design optimization

In the work I’ve described so far, I’ve relied exclusively on conventional volumetric and NURBS modeling techniques. But a new wave of design tools is out there — topology optimization and lattice generation, for instance — and they promise to create designs directly from functional requirements. Presumably these techniques would be just as applicable to my part as they are to the applications they’re already used on (mainly aerospace, biomedical, and other high tech applications). I’ve begun to explore this space, but the fact of the matter is that I’m not aware of a single consumer product today that was designed with these tools. My hope is that they both remove weight and make the part more visually appealing, but it could take a lot of work and some expensive (and experimental) software to find whether I’m correct.

Blatant editorializing: Gongkai for industrial additive manufacturing

Today, the viability of additive processes is totally opaque, producing a chilling effect on the creativity of both designers, service bureaus, and machine manufacturers. It’s my strong belief that that will only change by better understanding the efficiencies (and inefficiencies) of the additive manufacturing toolchain, and through my own work I hope to do just that.

In a series (one, two) of recent blog posts, Bunnie Huang describes the way that Chinese electronics manufacturers have been able to drastically decrease the cost of consumer electronics. To me, they provide an example for how additive manufacturing could advance much more quickly:

My most striking impression was that Chinese entrepreneurs had relatively unfettered access to cutting-edge technology, enabling start-ups to innovate while bootstrapping. Meanwhile, Western entrepreneurs often find themselves trapped in a spiderweb of IP frameworks, spending more money on lawyers than on tooling. Further investigation taught me that the Chinese have a parallel system of traditions and ethics around sharing IP, which lead me to coin the term “gongkai”… this copying isn’t a one-way flow of value, as it would be in the case of copied movies or music. Rather, these documents are the knowledge base needed to build a phone using the copyright owner’s chips, and as such, this sharing of documents helps to promote the sales of their chips. There is ultimately, if you will, a quid-pro-quo between the copyright holders and the copiers.

It would be an understatement to say that industrial additive manufacturing hasn’t adopted gongkai. Today, trade secrets & patents are the name of the game; the access I’ve been permitted (by Layerwise, DRT Medical-Morris, and countless other friends across the industry) is rarely afforded to others. It’s my feeling that this is bad, both for the technology as a whole and for the long term interest of individual players within it.

For instance: Anyone with experience could, given a part geometry and its build orientation, surmise more or less what the support structures will look like. If you have a physical part in hand, it’s even easier to reverse engineer; a part’s layer boundaries reveal its build orientation, and even with careful cleanup it’s generally possible to tell which surfaces have had support structures removed from them. In short, manufacturing forensics is, with enough experience and care, fairly reliable. And yet orientation and support structure setups are almost always treated as closely guarded secrets.

With so much uncertainty in industrial additive manufacturing today, firms are caught in something of a prisoner’s dilemma; their protective IP strategies prevent the industry from moving forward in the way that everyone ultimately wants it to. 

All around the world, intelligent, hardworking people trying to solve the most basic problems in additive manufacturing. Everyone in the industry knows what these are, and all of the major players are fighting tooth and nail to solve them first. And though it seems a long way off, I think most of them genuinely believe that they’ll see fully automated orientation & support structure generation within the next decade or two.

But today, the process of printing a part is decidedly hands-on; expertise is critical. “The people who are good at this stuff are good at it because they’ve been doing it for eight years,” one industry veteran told me recently. For sure, this industry is full of valuable intellectual property. But in most cases, *craftsmanship* is central to most firms’ bottom lines — and it is protected at all expense.

I believe that industrial additive manufacturing needs far, far more knowledge sharing. We need an environment closer to the one that Bunnie describes: 

We need “a ‘network’ view of IP and ownership: the far-sight necessary to create good ideas and innovations is attained by standing on the shoulders of others, and as such there [should be] a network of people who trade these ideas as favors among each other.”

In the coming moths, I’m looking forward to working on just that.

This post is just one in a series, and I remain convinced of what I’m working towards. With any luck — and more open collaboration with intelligent, committed people in the industry — I’ll have more to report soon :)

Thanks to

First, thanks to Martijn Vanloffelt and Tom De Bruyne, of Layerwise, for both their hard work and their willingness to help me understand how they work.

Second, thanks to Marcus Schröder, of EFBE, for both his hard work and the enthusiasm he had for testing my part — and discussing at length the testing & engineering cycle he sees in the industry today.

Thanks also to Dave Bartosik, of DRT Medical-Morris, and Dustin Lindley, of UCRI. Their continued technical help has been an incredible asset, without which I may never have begun this project.

Thanks also to Clay Parker Jones and Bradley Rothenberg for reading early versions of this piece.

First EBM prints

Added on by Spencer Wright.

A few weeks ago I visited Addaero Manufacturing, one of the very few EBM (electron beam melting) service providers in the US. After my recent trials (and successes) with laser powder bed fusion, I wanted to try building parts with EBM. EBM is used extensively by aerospace and medical OEMs, but its penetration into the job shop world is way behind laser. Addaero, whose founders (Rich Merlino and Dave Hill) both worked at Pratt & Whitney before striking out on their own, is located just a few hours from New York City, and they were gracious enough to build two parts for me to evaluate the process.

I'll be writing up a longer post on the unique design considerations that EBM poses, but for now I wanted to share the pictures I took while there:

At this point, the parts Addaero made for me still need post processing before they can be assembled and tested. I'll be working on that over the coming weeks, and will update soon on my progress.

Things that are on my plate right now

Added on by Spencer Wright.

Mostly for my own benefit & the sake of catharsis, here are the things that are consuming my attention over the past & for the next few months:

  • Planning my own wedding in October.
  • Having fun this summer.
  • Getting more exercise.
  • Writing a long blog post on the seatmast topper that I had printed (DMLS) by Layerwise, and then tested by EFBe. 
  • Writing a long blog post on the seatpost that I had printed (EBM) by Addaero.
  • Digging more into McMaster-Carr's iOS app, and comparing it to Amazon's recently rebranded Business offering.
  • Planning a sourcing trip to Shenzhen, where Zach and I will investigate a significant redesign of The Public Radio's speaker & mechanical assembly.
  • Getting more hands-on experience with metal powder bed fusion machines. Because there are none in the New York metropolitan area, this inevitably means traveling for a few days to somewhere where I have a friend in the industry.
  • Doing a deeper dive into the variety of design tools that are cropping up for additive manufacturing. This includes getting better at T-splines (Autodesk Inventor), working with topology optimization software (SolidThinking Inspire; Frustum Cloudmesh), and doing some experimenting with lattice structure generation (with nTopology).
  • Doing a deeper dive into build preparation software, namely Materialise Magics.
  • Building myself a real desk, preferably with a proper toolchest integrated into it. I also want 2x24" displays, a proper Windows computer for 3D design, a new Mac for daily use, and a place for both a Wilton "bullet" vise and my 12"x18" granite surface plate.
  • Writing a presentation on metal 3D printing that covers both my experiences over the past two years (a case study), and my broader observations on the industry. 
  • Getting said presentation accepted to an industry conference (likely either AMUG, RAPID, or Inside 3D Printing).

There are a few more longer-term things, but this is a pretty good list for now. 

Measuring process signatures is hard

Added on by Spencer Wright.

From a NIST report titled Measurement Science Needs for Real-time Control of Additive Manufacturing Powder Bed Fusion Processes:

Finally, metallic debris from the [heat affected zone] can coat a window or viewport used in an AM imaging system, and disturb temperature measurements by changing the radiation transmission through the window. This is particularly troublesome in electron-beam melting (EBM) systems, and prompted Dinwiddie et al. to create a system to continuously roll new kapton film over the viewport in order to provide new, unsullied transmission.

This is a very important and totally nontrivial challenge. Measuring process signatures (which this report defines as "the dynamic characteristics of the powder heating, melting, and solidification processes as they occur during the build") is key to the industrialization of additive manufacturing. If the systems we have for measuring those factors are unreliable, machine manufacturers need to develop improvements for them ASAP.

The six questions I think about when I think about industrial additive manufacturing

Added on by Spencer Wright.

Prompted by an impromptu back and forth with Jordan, I was compelled to write down the things I spend so much of my time thinking about. Some of these I have a better grasp on than others, but they're all problems that I'm excited to see developments on - and work on myself.

1. What are the process parameters that affect finished part shape?

I'm in the middle of a NIST report that goes through many of these. The sad thing is that knowing what the parameters are is only half of the battle; then, you need to control those parameters on-the-fly (which is not something that all machine manufacturers currently allow).

2. What are the most reliable and effective methods of measuring, recording, and processing those parameters?

Industrial additive manufacturing machines tend to be harsh environments for sensors and sensor hardware. Once we know what parameters to measure, we'll need to build measurement systems that are robust, accurate, and reliable.

3. Given two identical finished parts with two different production process chains (additive, subtractive, etc.), how can one determine which process chain will be more expensive to complete?

This is hard. I believe that it'll be easier to automate process chain comparison than it will be to automate process chain creation; in other words, coming up with a list of steps to manufacture a part will remain hands-on, but assessing the cost difference (time/money/energy) between two process chains will be increasingly automated. Regardless, these are big problems.

4. Given two different designs, each of which has the same end functionality, how can one determine which design will be more expensive to build?

This feeds into question 3. In many cases today, design decisions are made based on a hunch. If it were easier to estimate the production cost for parts with complex production process chains, designers would be able to make more informed decisions.

5. Given the same input design and two different additive build orientations, how can one determine which build orientation will produce the most high fidelity net near shape, at the lowest cost?

Also feeds into question 3. Manufacturing engineers need to pick a build orientation quickly and be guaranteed high fidelity end parts; today, those decisions are made mostly by gut. Bonus points if this data is also made available to designers, so that they can make even more informed design decisions.

6. Given the same input design and build orientation, how can one determine which support structure design will produce the most high fidelity net near shape?

Given the early effort that startups (namely 3DSIM) are putting into this question, it stands to reason that it's an easier one to solve than question 5. It's also possible that they think it'll be easier to commercialize support structure optimization software in the near future. Either way, I see this as just part of a bigger need that 5 and 6 are pointing at together: additive manufacturing engineers need better tools to set up and process builds.

These issues outline the biggest roadblocks that I've experienced on my path to commercially viable additively manufactured parts. If you have different experiences, or know of developments on what I've described here, I'd love to hear from you.

CT Scanning of 3D printed parts

Added on by Spencer Wright.

A few weeks ago I visited CIMP-3D by invitation of its co-director, Dr. Tim Simpson. I was there partly just to visit (I love these kinds of places), but also to see first-hand the role that CT scanning can play in non destructive testing of additively manufactured parts.

CIMP-3D is located at and operated by Penn State University, and serves as part of Penn State's Applied Research Lab - and as an Additive Manufacturing Demonstration Facility for DARPA. In aggregate, they help both government agencies and commercial partners qualify and improve parts made by powder bed fusion and directed energy deposition. In their well-equipped shop, they have two powder bed fusion machines: an EOS M280 (EOS calls their process "DMLS", a term that I continue to get flack for using generically :) and a 3DSystems ProX 200 (3DSystems calls their process, which was developed out of their 2013 acquisition of Phenix Systems, "DMP" - for "direct metal printing). For their work on directed energy deposition, they also have an Optomec LENS MR-7 (a laser based powder deposition machine), and until recently had a Sciaky EBAM (a large scale wire fed electron beam welding machine, which had been sold just prior to my visit).

While I was excited in see their directed energy deposition machines, the real attraction was their GE phoenix v|tome|x m300 CT scanner. This machine is made by GE Measurement & Control division, which is part of GE's Oil & Gas business unit (it should be noted that I've done consulting for both M&C and O&G, though not for the people who make CT scanning equipment). CT scanners are *expensive* (close to $1M, depending on options), and are basically unheard of in private service providers. They can be used to analyze both the as-built form of a part (which will often deviate from the as-designed form significantly), and also any flaws (cracks and voids) which would make it unusable.

Before I visited CIMP-3D, Corey Dickman (an R&D Engineer there) was kind enough to print one of my seatmast toppers, in aluminum, on their EOS M280. It came out well, with only a small defect in the seatmast clamp area. Corey used some pretty clever support structures, tapering them in order to provide a balance between a solid grip on the plate on the one hand, and relatively low material usage on the other:

CT scanning uses a series of 2D X-ray images to reconstruct a 3D part. In CIMP-3D's scanner, the part is placed on a turntable in the middle of the machine. The X-ray projector, on the right side of the machine, shines X-rays through the part onto a sensor on the left side. Solid parts block X-rays, creating shadows on the sensor, and the result is a greyscale image where dark areas correspond with solid mass and light areas correspond with empty space. 

The scan moves pretty slowly. My part was scanned in 3500 slices, or one scan every ~.1 degrees. At this rate (and at a voxel size of 58µm), the total scan time was about an hour. Each scan takes about a second, and between scans you can see the turntable rotating slightly.

Fixturing the part in the machine presents an interesting challenge. You want it to be held securely, but you don't want any other solid things touching it - as they will cast their own shadow in the X-ray images. As a result, parts are often held in place by simply sticking them into a piece of styrofoam - as mine was.

Once the data is captured, it's loaded into a separate workstation to be reconstructed. The amount of data that needs to be processed here is staggering - my scan generated about 25 gigabytes of image data, which reconstructed into a 5.7 gigabyte model.

Once the reconstruction was complete, Griffin Jones (the R&D Engineer responsible for CIMP-3D's CT scanning) was able to do a visual analysis of the as-built part, checking it for voids and flaws. The as-built model can also be overlaid on top of the as-designed model, allowing for deviations to be easily quantified. The model can also be explored layer by layer in any orientation, allowing for a really complete understanding of what the solid part looks like:

A word on resolution: this scan was performed at a voxel size of 58µm, and each voxel is assigned a greyscale value that corresponds with the material's radiographic absorption coefficient at that location. However, any given voxel is subject to some amount of randomness as well; if a voxel has a vastly different value than its neighbors, then the operator needs to determine whether that's a result of a microscopic void, or a result of random variations. 

As a rule of thumb, Griffin assumes a void when he sees three voxels in a row with low grey values. Interestingly, the scan did reveal a few tiny voids in my part. They're mostly near the edges - specifically, the zone right at the boundary of the profile scan (the perimeter of the part's cross-section) and the infill hatching. Since the scan was performed at a voxel size of 58µm, and Griffin was looking for three voxels in a row with low grey values, the voids we detected were about 180µm - just larger than the diameter of a human hair. 

My suspicion - which would need to be verified by destructive testing - is that voids of this size are probably well within the functional requirements of my design. Of course, this particular model is aluminum, and the design is meant for titanium - but I'm looking forward to having a ti model scanned and destructively tested in the future.

For most product development teams, non destructive testing (NDT) is just one part of the process of qualifying a new part. My part, for instance, is being put through physical load testing this week - and I'll use the data I get from that test to improve my design. But for early on in the build planning process, having a tool that allows you to dive inside otherwise obscured areas of your part is incredibly helpful. Especially in the case of complex, topology-optimized parts with organic forms, it can be difficult to impossible to measure a part's deviation from the underlying design. Moreover, there may be regions that it's impossible to inspect without destroying an expensive prototype. My part has just this: the front of the neck section contains a completely hidden hollow zone. And as I move into redesigning for EBM, knowing the areas where powder tends to cake up will be even more helpful.

Thanks so much to CIMP-3D for hosting me!

A successful print

Added on by Spencer Wright.

The other day I got a package from Layerwise. In it was the second titanium seatmast topper of mine that they printed, and this one is ready to ride.

...but actually, this part might not actually be ridden - it's off to Germany to be tested. I'm in the process of writing up a longer report about how the project has gone over the past month or so - expect that soon!

T-spline redesign

Added on by Spencer Wright.

As my seatmast topper has been moving towards destructive testing, I've been playing with a new seatpost design. This part would probably be EBM'd, and then bonded (with 3M DP420 or similar epoxy) to 27.2mm carbon fiber seatpost stock. I suspect that this design will be a bit more economical, and would work on a wider range of bicycles - including my own.

I've been pursuing the redesign in a few ways. First, I've been working with a few NYC folks to develop designs that incorporate either topology optimization, or lattice structures, or possibly both (more on this soon). Second, I got a trial license of SolidThinking Inspire, and have been using that to reduce mass within a design space that I set up in Inventor. And third, I took a crack at designing the part from scratch with T-splines in Inventor, which I *really* enjoy.

T-splines are a totally different way of approaching design, and they allow you to manually create organic looking structures. Once I've created the organic shape, I apply a bunch of features to it in Inventor's solid environment - allowing me to blend precise mechanical aspects within an otherwise fluid shape.

Ultimately, I'm optimistic that topology optimization & lattices will offer a less labor intensive workflow. T-splines are *awesome,* but editing them is a bit of an art, and I'd like to be able to redesign the part quickly to accommodate different saddle offsets, strength limits, seatpost diameters, etc.

Expect more progress soon :)

Tested.

Added on by Spencer Wright.

After more than a year and a half of research, modeling, procurement, site visits, redesigns, and batches of failed parts, I've finally got a functional, 3D printed, titanium seatmast topper.

Yesterday morning Clay and I took it for a 20 mile ride, and aside from some cosmetic issues (he *really* needs a ti stem now...) it worked well. We'll road-test it a bunch more over the next few weeks.

I'll go into detail in a long post soon, but the short story is this. This part was built by Layerwise, a Belgian startup that was acquired by 3D Systems last year. While Layerwise has a bunch of IP (software + hardware) that allows them to tune the process parameters, the main difference between this part and my earlier prototypes is the build orientation - and some clever use of temporary structures and supports. This part was also shot peened, which (along with the orientation change) improves the surface finish noticeably.

I'm expecting another copy of this part in the next week or two; it will go to be destructively tested in Germany. It's only slightly different than this one: Layerwise is adding some additional supports in the the seatmast clamp window, which will help it from distorting slightly during the build process.

Once the part is destructively tested, I'll get a better idea of the areas where I can remove material in order to make the part lighter. I've been wanting to redesign the part for a while - partly to reduce the need for support structures, and partly for aesthetics. The most likely path for both of these is to introduce a number of lattices, which will likely be lighter, be easier to build, require less post processing, and be more visually compelling and distinctive. I've got a few thoughts on what this should look like, but will also be working with some software & design companies who have more experience with lattices.

Having a working (albeit imperfect) part in hand is a really validating step. I'm *really* looking forward to more of these - and to critically evaluating their performance.