“Made in State College”: Developing Manufacturing Processes for Lower Limb Prosthetics

Overview

Impulse Technology LLC is a startup company at Penn State Innovation Park focused on the designing and fabrication of a passive prosthetic ankle to allow a prosthetic leg to more closely mimic human movement. Impulse tasked the team with developing manufacturing processes for their product, a prosthetic ankle-foot. The team is to develop a process for their current design using their benchtop CNC at Innovation Park with aluminum alloys as the materials. The deliverables are fixturing and tooling for the designs and a demonstration of the manufacturing process with a prototype.

Objectives

– Develop a manufacturing process for the top support part of Impulse Technology’s prosthetic ankle-foot product using their benchtop CNC

– Develop a process within tolerances specified by Impulse Technology to ensure compatibility with humans and standard prosthetic devices

– Create a functional and aesthetically pleasing product with aluminum alloys

– Minimize the cost of parts needed for the ankle-foot prosthetic manufacturing process

– Optimize machining time to increase the feasibility for on-site manufacturing production

Approach

– Conduct initial research of milling techniques, types of CNC, and necessary material availability (i.e., end mill sizing)

– Develop G-Code using Fusion 360 for the HAAS CNC in the FAME Lab. This code will be used as proof of concept that the part could be machined and serve as the first prototype. It will later be used as the foundation of operations for the Impulse Technology benchtop CNC Router for the final product

– Alter G-Code to fit the limitations of a smaller benchtop CNC router. All speeds, feeds, tool specifications, and operation settings will need to be changed in order to be successfully run on a smaller machine. The type and order of operations will remain constant from the prototype code

– Validate manufacturing process by running the entire code on the benchtop CNC router on a stock Aluminum 7075 piece

Outcomes

– Developed a successful manufacturing process to allow Impulse Technology to produce products and prototypes in house. Cost analysis shows a savings of $29.09 for one part produced in house versus third party manufacturing

– Implemented a vice for the benchtop CNC router T-table at Impulse Technology. By including a fixture into the table, it eliminates the need for the waterbed, saving clean up time and reducing materials necessary to machine. It also creates a set point for parts to be machined in the same spot. This negates the need to re-zero after removing the part from the CNC saving the operator time and improving accuracy

– Defined all tool specifications and operation settings in Fusion360 that can be applied to future milling done on this CNC