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Producing Higher-Quality Parts Faster

AM may be the future for some types of manufacturing, but one firm’s expertise and experience shows the technology’s competitive advantages lie with part design and innovation.

Forecasts indicate that additive manufacturing will achieve the largest percentage of growth in the manufacturing over the next 10 years, reconfirming the notion that AM (aka 3D printing) is the up-and-comer technology in today’s workplace. Not only has it started to play a role in R&D and prototyping, but now AM processes are making progress in production. It’s time to examine how AM can play a role — directly and indirectly — in metalcasting operations.

Innovative 3D Manufacturing and Innovative Casting Technology are using AM, now, to define manufacturing and service for the future. We have learned how to use AM technology as part of our daily operation, and we take pride in “thinking outside the box” to produce parts quicker, and of higher quality, than our competitors. Consider:
• Fused Deposition Modeling (FDM) machines:  95% of our coordinate measuring machine (CMM) fixtures are produced now by our FDM Printers. We are able to produce a high quality, stable fixture that can nest our parts while we check all critical features. Notably, these fixture weigh 80% less than a traditional fixture and can be produced with minimal operator intervention. In most cases we produce an extra fixture to send to customers, and we have noticed a better correlation between our own and the users’ QC departments: Parts are held exactly in the same orientations and at the same locations. This allows us and the users to run the same PC-DMIS CMM program, which leaves less room for error.

• FDM machines/stereolithography (SLA):  FDM- and SLA-printed parts work well for CNC machine set-up pieces. Part profiles printed into custom jaws and workholding fixtures effectively reduce set-up times. Actual plastic part prototypes work well to test for fit and function. Designers want to hold a part in hand after design is complete, and the SLA process works well to show what changes need to be made to make a part AM friendly. And all this can be done in less than 24 hrs.

• Direct Metal Laser Sintering (DMLS) technology: State-of-the-art Renishaw DMLS technology allows Innovative 3D to maximize the parameter settings for almost any material type. The machines print from 20 to 100 micron layer thickness. Scan paths can be altered to account for thin-wall conditions, so that no over melt occurs.

We work closely with Praxair Surface Technology, developers of hundreds of different AM powders, and the Renishaw machine offers a reduced build volume chamber to conduct powder and parameter trials and testing. Metal AM has made it possible to produce a functionable metal parts in days instead of weeks or months. It also eliminates the need to build a foundry tool to produce a single part.

Metal AM has helped address the "skills gap" in manufacturing too: More than 50% of the metal AM parts we produce do not require post-process machining. The flip side to this is that parts that need machining require a highly skilled machinist who understands geometrical tolerancing and is creative with workholding. The machinist typically will work with the design engineer to add machine stock to critical areas of the part. In most cases there is just one part, so scrap is unaffordable, and attention to detail is essential.

• DMLS part density and machine tolerancing:  DMLS parts come off the machine as 99.5% dense. Some customers require Hot Isostatic Pressing (HIP), which can make the parts 100% dense. There is no visible porosity and the DMLS parts machine like solid bar stock. Surface-finish conditions off the machine is 120-200 micro inches, which can be improved very quickly with a sanding disk. Part tolerances of 0.005 in. or less can be held consistently, depending on material, part geometries, and build orientation.

• Special projects, designs, and materials: Metal AM parts fit the bill for customers that needs one off development parts and prototypes (e.g., 316 SS, Inconel 625, Inconel 718 and AlSi10mg) or low-volume, small envelope casting alternatives (AlSi10mg and 316 SS.) It’s also an effective production method for parts with complex geometries that cannot be cast or machined:  Simple things like square pockets with square bottoms are possible now, without broaching or hand work. AM allows design teams to combine several components into one more complex model. Internal geometries, lattices, and honeycombs are possible. And, if a customer wants to lighten up a part but still wants a strong design there are several software programs available to optimize part topology.

• Thin wall geometries, small holes and other small complex features:  DMLS machines will print thin-wall geometries very well, such as a series of heat sinks with  0.020-in. thick walls printed in AlSi10mg. The machines also print exceptional quality parts in Ti64.

As the world of AM expands we see that it is not offering customers a chance to make a part with a new and different manufacturing process; In most cases the traditional process will be more efficient than AM. The prospect of AM is the design freedom it offers, to produce efficient, high-performance parts.

But, accommodating AM process characteristics is essential to building production parts with minimal cost and waste. Designers may need to combine various techniques – topological optimization, hollow parts, lattices (where applicable) – to achieve an efficient design. Orientation should be the driver ,after fit, form, and function. Designers will have to be smarter and more knowledgeable about the additive manufacturing process if they want to be competitive for the future.
Chris Beck is the co-owner and manager of operations for Innovative 3D Manufacturing and Innovative Casting Technology, Franklin, IN. Contact him at [email protected] or visit www.Innovative3DM.com / www.Innovative-Castings.com

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