Additive Manufacturing’s Dirty Secrets Exposed
Over the past few years, additive manufacturing (AM) and 3D printing have been generating a lot of interest, along with their fair share of hype.
3D printing has been around for decades, used primarily for rapid prototyping. But new applications spurred by advances in technology and materials – not to mention the growing and wildly enthusiastic DIY crowd with their inexpensive MakerBot and RepRap home printers – has generated a lot of column inches in trade, business and consumer publications, stories liberally sprinkled with terms such as “game changing,” “disruptive,” and “revolutionary.” Digital Manufacturing Report is no exception.
So it’s no wonder that organizations like the U.K.’s Technology Strategy Board (TSB) are taking note of the technology and asking some tough questions. TSB’s role is to “stimulate technology-enabled innovation in the areas which offer the greatest scope for boosting UK growth and productivity.” It does this by supporting and investing in technology research, development and commercialization. AM is very much on their radar.
But despite all the hyperbole, the Board, in a recent competitive announcement, noted that “As a well-established tool for rapid prototyping and tooling, this technology is also capable of enabling new approaches to the design, manufacture and distribution of end-use components and consumer goods in a wide variety of global market sectors from aerospace to jewelry. Although this disruptive toolset has been described as revolutionary and game changing, actual take-up and market growth has been relatively slow.”
And why is AM dragging its feet, when according to the pronouncements in the press it should be taking over the world? It all comes down to what industry insiders call “the dirty secrets of additive manufacturing.”
Enter Robin Wilson, the Technology Strategy Boards lead technologist, high value manufacturing. Talking to AM companies and colleagues in the U.K., Wilson decided to bring these secrets out in the open by running a competition designed to not only subject these problems to the bright light of day, but come up with solutions designed to help the U.K.’s AM industry compete in the world markets with the likes of the U.S. and Germany. He said his proposal was met with surprise and delight on the part of AM industry members – “Would TSB really to that,” they asked. “Just watch,” replied Wilson.
The competition opens December 3 and closes March 27. TSB, Engineering & Physical Sciences Research Council (EPSRC), Arts and Humanities Research Council (AHRC) and the Economic and Social Research Council (ESRC) are investing up to £7m in collaborative research and development to stimulate innovation in additive manufacturing.
Dirty Secrets Exposed
And just what are some of those dirty secrets the competition is addressing?
“One that we can do something about is pre- and post-processing,” says Wilson. The hype would have you believe that working with a CAD program, you can, in theory, create any shape you like – even one with complex internal geometries – and then just print it out with the push of a button.
However, the reality is far more complex. For example, suppose you are creating a complicated component using an AM process based on metal or plastic powder. When the external structure solidifies, it may not have the requisite internal support and the part distorts, rendering it useless. Engineers need to understand the weaknesses in the process and come up with a clever way to analyze the design to determine whether it needs temporary internal structural support – a process that should be automated.
Post-processing is another part of the AM mystique. Read an AM product brochure and you’d think that you just remove the part from its powder bed or from its base in a Fused Deposition Modeling machine and you’re good to go. Not so, claims Wilson. “Post processing is very manually intensive and a lot more variable. In the world of short runs, this really doesn’t matter. But when you get into even medium volume production runs, these issues become very important.”
He points out that there is no such thing as additive manufacturing per se – in fact, the TSB Additive Manufacturing Special Interest Group (SIG) has issued a comprehensive report titled Shaping our National Competency in Additive Manufacturing, in which it lists seven different AM processes based on ASTM classifications.
• Powder bed fusion
• Directed energy deposition
• Material jetting
• Binder jetting
• Material extrusion
• VAT photopolmerisation
• Sheet lamination
Each of these categories has a different set of benefits and different challenges – each has its own “dirty secrets.”
One of the problems afflicting all of them is the high cost of the process, which correlates directly with the speed at which the parts are manufactured. One way to speed up deposition on AM systems based on a lasers or electron beams, is to use bigger increments – bigger layers, larger particle sizes, or more energy input. However, the dirty secret here is that this approach makes it difficult to control accuracy.
Another speed bump is a lack of AM industry standards – for example a lack of processing standards means that when the same CAD design runs in machines from Eos, Objet or Stratasys, the results will differ.
Inconsistent material standards also plague the industry. Wilson notes that the other AM companies prefer that you use their consumables in order to achieve predictable results. And, of course, like the cartridges for ink jet printers, the sale of the proprietary materials ensures a continuous revenue stream for the company. What’s needed is the creation of a supply chain that feeds into a number of different manufacturers, lowering both the cost and the risks associated with being dependent on a single vendor. He notes that the today’s situation is not necessarily bad; it’s just a stage that the AM industry is currently moving through on the way to its next phase of maturation.
“There is the possibility for 3D printing and additive manufacturing to have a major impact on the manufacturing industry,” says Wilson. “Design is the key.”
He points out that if you take existing components that are made, by metal forming or injection molding, trying to clone them using AM probably will not yield that much of an advantage. However, if you can design a part specifically for manufacture by AM, one that has higher functionality and better volumetric and material efficiency as well as incorporating some clever features that could not be made by conventional processes, then, says Wilson, you stand a better chance of creating a unique product and gaining a competitive advantage.
In the meantime, the TSB competition has been launched with its stated goal of overcoming the barriers to growth of the AM industry in the UK and globally – those dirty secrets that include high costs, inconsistent material properties, lack of applicable industry standards, unexpected pre- and post-processing requirements, and the failure to exploit the new design freedom offered by the technology. As the TSB announcement of the competition says, “By investing in these target areas, we aim to accelerate the creation of exciting new design, production and supply chain competences for UK businesses.”
And clean up a lot of dirty little secrets in the process.