Thermwood Corp., a former molder and longtime manufacturer of machine tools called CNC routers, is now entering the additive manufacturing business with a very high-volume, high-tech machine that initially will target aerospace pattern and tooling applications.
The Dale, Indiana company has developed unique, patent-pending layering technology and built an R&D system that can make carbon graphite reinforced ABS sections that are up to ten foot by ten foot by five foot high.
A vertical 20 hp, 1.75-inch diameter, 24-1 L/D American Kuhne extruder that can feed more than 100 pounds of material per hour is integrated with a full six axis articulated additive deposition head developed by Thermwood. The machine structure is Thermwood’s Model 77 semi-enclosed, high wall gantry machine, which is currently offered in sizes up to sixty feet long. With the addition of an optional second gantry, both additive and subtractive (machining) processes can be performed on the same machine.
Layered structures can be built on both a horizontal plane as well as planes canted in any direction up to ninety degrees from horizontal, says Ken Susnjara, Thermwood chairman and CEO. “We believes this capability will be important as technology advances and more complex structures are required,” he says.
Once the part cools and hardens, it is then five-axis machined to the final net shape.
“The fundamental approach we are taking is different than others who are doing research in this area,” Susnjara told The Molding Blog. “Others are trying to modify the resin to eliminate parts warping when printed parts are heated in an autoclave which is required for the pattern/mold application. We are working to create physical structures which cannot be generated with simple three axis machines but which will by their basic physical nature resist warping when heated and cooled.”
Thermwood plans to use a 15-20 percent carbon graphite fiber filled ABS as the initial test material. “We turned to graphite composite material because we need the strength and physical properties which are not available from unfilled ABS.” The company is working with undisclosed resin manufacturers who are current customers.
Themwood is currently working with a customer who will evaluate and test the products being made. Model 77 has been used for the trimming operations on additive manufactured parts for several years.
Thermwood was established in 1969 as an injection molder of wood grained plastic parts for the furniture industry, hence the name “Thermwood”. In the mid-1970s, it developed the first commercial CNC machine tool control and used it to build machinery to trim plastic parts. Thermwood began selling this trim equipment for plastics, composites and woodworking applications and the CNC router was born.