Part 1. WPI & Wenext

Wenext strives to help college students to fulfill their dreams. Last year, Wenext approached Worcester Polytechnic Institute (WPI) and sponsored the race team of WPI in SAE Formula Hybrid + Electric Competition hosted at New Hampshire Motor Speedway subsequently. Wenext delivers CNC Machining car components to the team and gain great feedback. The Competition is an interdisciplinary design and engineering challenge for undergraduate and graduate university students. Students in this event have to design and build a formula-style hybrid or electric-only racecar, and the car should compete a series of events.

Image Source: WPI

Part 2. Car Designs 

WPI race team worked with Wenext throughout the majority of the car building season, starting in the winter months. Wenext utilized CNC Machining to manufacture two different products for WPI team, including four wheel-hubs and a motor shaft.

For the design of the wheel hubs, the team primarily wanted to incorporate the use of double row angular contact bearing that used in a previous iteration of a car (prior to the team’s switch to designing for an electric vehicle), while retaining features that the RCV Performance wheel hubs offer. Additional design considerations for the front wheel hubs included adding external threads to the end of the wheel hub such that the team could use a fine-threaded nut to hold the wheel in the upright and preload the wheel bearing appropriately.

For the design of the motor shaft, the team had two primary design considerations which included the predetermined bolt pattern on the shaft’s mounting interface to the motor, and the distance from the motor to the sprocket, which was fixed to align with the differential. Additional considerations included choosing a material for the shaft (8620) with high strength and toughness such that it will have a greater resistance to developing cracks as compared to other materials considered. The team designed the motor shaft to withstand the full torque of the EMRAX 228 at 230Nm. Since this torque should never be reached (due to other factors such as accumulator output and tire adhesion limits), it provides a good buffer to allow the system to support more in the future. Another design element was the use of an involute spline to prevent the shaft from slipping (as it serves as the link in power transmission between the motor and sprocket). The team decided on this method (over others considered) due to the high torque and ease of fitting off shelf sprockets. Besides, the team also took this a step further for increased manufacturability and simplicity by designing the spine to be approximated with trapezoidal teeth. Finally, a threaded end was incorporated into the design such that a locking nut could be used in assembly.

The CNC Machining parts were manufactured and shipped in a very efficient manner, and were sent in time for assembly. “Wenext maintained a strong line of communication throughout the process, and the resulting products were manufactured well to our design specifications.”, said by Harris, the Formula SAE Club President of WPI.

Wheel Hub

Motor Shaft

Image Source: WPI

Part 3. Comments and Feedback

“The quality of the CNC parts were excellent. Everything was manufactured to the specifications of the drawings provided and performed well on our electric car. The parts performed as designed in all events our team competed in, both in static inspections and dynamic competition events.”, said by Harris. The car competed and placed 4th overall and earned an “Excellence in Electric Vehicle Engineering Award” in the competition.

“Wenext maintained a line of communication from across the globe and provided the parts in time for our car to be assembled and participate in the competition. We initially designed these parts for our manufacturability, however, when the opportunity for a sponsorship arose for these parts to be manufactured at Wenext, we were happy to work with Wenext, and were pleased with the outcome.”

Image Source: WPI