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polymer material can be used, depend- ing on the application. Polylactic acid (PLA) is perhaps the most common filament and is often used for invest- ment casting and sand casting patterns. Other plastics, such as ABS or nylon, require a heated chamber for print- ing but are more rigid for sand mold tooling. All are available with “fill” such as graphite, fiberglass or even wood to increase strength and durability. As companies experiment and test


the equipment, better and more effec- tive methods and practices are start- ing to emerge. Miller recalls an early project to print a replacement tool for a pump that was experiencing core tilt that resulted in 90% scrap. Flowserve provided a master 3-D model and the tooling was printed via FDM. Te pro- jected timeline was four weeks, includ- ing 12 days for tool printing. In reality, printing the tool took 24 days because of two failed prints. Ultimately, the castings were produced and verified, with lessons learned about how printed polymers behave in the equipment. Miller points to two later exam- ples to show how the methods his suppliers are using have improved by using what he calls a “system.”


Printing inserts that will go into picture frames or bolsters saves printing time and material cost. “Only print what you need,” Miller


said. “You are building, you are not cutting away. A lot of foundries run inserts in their pattern equipment. So, you can make a standard size insert for a picture frame or bolster where


you drop your print into the frame. You are not building all the other portions of the tool that are standard. It drops the build time a lot.” Flowserve has worked with at


least two suppliers who have incor-


The 3-D printer Matthew Loerwald built for the Martin Foundry in Dallas printed the pattern on the right in sections that were then glued together for the full pattern.


24 | MODERN CASTING April 2017


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