Kennametal, a supplier of tooling and industrial materials based in Pennsylvania, has developed a 3D printed stator bore tool in response to growing demand from automotive customers.
The tool is designed for machining components on hybrid and electric vehicles, developed specifically for e-mobility automotive manufacturers seeking lighter tooling. Components of electric vehicles are often machined on smaller, low horsepower CNC machining centers, which requires lighter weight tooling solutions compared to standard automotive practices.
Kennametal used 3D printing to create two stator bore tools, the stationary part of a rotary device on a machining system, both weighing less than half of their traditionally manufactured counterparts. “The main bore, that houses the stator of an electric motor measures approximately 250 mm in diameter (9.84″) and approximately 400 mm (15.74″) in length, with a smaller bearing bore at the bottom,” explained Harald Bruetting, Manager, Program Engineering at Kennametal.
“When manufactured using conventional means, a reamer for this type of application would weigh more than 25 kilograms (55 lb.), far too heavy for the existing machine tool or for an operator working with the tool.”
Tooling and additive manufacturing at Kennametal
Founded in 1938 and headquartered in Pittsburgh, Kennametal develops a variety of metal tooling products and materials. For example, the company has blades, disks, skins, fuel control systems, and landing gear products for the aerospace sector. It also develops a number of lathes and fixtures for machining industries, and provides tooling for customers in automotive.
The company’s 3D printing division, named Kennametal Additive Manufacturing, offers metal powders, optimization and prototyping, and series production services for additive manufactured parts. Parts are produced using Kennametal’s internal binder jet and laser powder bed 3D printing technologies. Its in-house 3D printers includes the X1 25PRO metal binder jet system from leading industrial 3D printer provider ExOne. Kennametal was named as a beta tester of the 3D printer by ExOne in May 2019, alongside Swedish engineering group Sandvik.
Developing lightweight automotive tool using 3D printing
To meet the demands for a lightweight CNC machine stator bore for its e-mobility automotive clients, Bruetting and Kennametal’s Solution Engineering Group referred to the company’s additive manufacturing solutions. Two iterations of the tool were manufactured using metal powder bed 3D printing. The first featured a carbon-fiber tube, weighing 9.5 kg (20.9 lb.), and the other was equipped with a 3D printed metal tube, coming in at 10.7 kg (23.6 lb.). Both met the lightweight requirements of the tool, weighing less than half of the standard stator bore, which measured at 25 kg.
The tools were also designed to match the accuracy, roundness, strength and surface finish requirements set by standard stator bores as well, using Kennametal’s technologies. The company equipped them with its RIQ reaming inserts to enable high precision finishing, and its KM4X spindle adaptor for maximum rigidity. Both tools also have internal 3D printed cooling channels that are intended to help boost their productivity and longevity.
“By using metal powder bed 3D printing together with finite element analysis software, we were able to design and build a tool that brought the moment of inertia very close to the spindle face, increasing its rigidity while meeting the customer ́s weight restrictions,” commented Werner Penkert, Manager, Future Solutions. “It is an excellent example of how Kennametal is using advanced manufacturing technology to help meet our customer’s unique challenges.”
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Featured image shows 3D printed stator bore equipped with RIQ reamer and KM4X adaptor. Image via Kennametal.