Put to the test: Trine group’s device will evaluate outdoor chairs

With its emphasis on sustainability and quality, including a 20-year warranty for its products, outdoor furniture manufacturer Polywood felt it needed to improve testing methods for its swivel chairs.

A Trine University senior design team developed a new device for that purpose over the course of the school year.

The new tester, designed by mechanical engineering majors Sean Carpenter, from Fort Wayne, Indiana, David Petersen, from Zionsville, Indiana, Ethan Wallace, from Hope, Indiana, and Johnathan Wilder, from Decatur, Indiana, provides more flexibility and durability as well as a greatly improved user interface.

‘Very impressed’

Polywood decided to reach out to Trine about improving the tester after members of the company visited the university on a recruiting trip for its engineering team.

“We were very impressed with the resources of the program and the results of other design projects,” said Jamin Hochstetler, testing team leader for Polywood. “As a company with ever-growing engineering needs, partnering with an engineering program as comprehensive as Trine's was an easy choice that was mutually beneficial.”

“We felt this project would be great for a senior design project because it required multiple engineering disciplines, had an existing base that could be built upon, and had a timeline that fit within the team's semester schedule.”

The previous tester had a fixed rate of eight revolutions per minute. It featured a mechanical reversing switch that allowed the machine to rotate back and forth but was prone to failure.

It also lacked the ability to precisely stop after a desired number of cycles.

“Polywood also expressed interest in receiving more data on their chairs in terms of how the torque applied to the chair changes over time,” Carpenter said. “This data will allow them to get a better idea of how their chairs perform over time combined with taking a closer look at the bearing in their chair.”

A trip to Polywood

Early in the fall semester, the team traveled to Polywood’s facility in Syracuse, Indiana, where they were given a site tour and discussed the project with the testing team and management.

The group translated the needs expressed by Polywood into a list of quantitative requirements, then developed concepts to meet or exceed those requirements.

The team sized the motor and gearbox to turn the chair on the tester with 280 pounds of weight. They also worked to create a safe, stable frame that could handle the tester’s loads.

They applied knowledge from electrical and computer classes to create a functional programmable logic controller (PLC) and human machine interface (HMI) combination that could read and display torque, cycle count and time remaining. 

“We changed just about everything,” Petersen said. “Each subsystem was analyzed and redesigned.”

The end product features a more powerful, controllable drivetrain, a user-friendly interface and an 80/20 enclosure.

Through the process, the group gained substantial experience in engineering design, project management, manufacturing and fabrication, and PLC coding and troubleshooting.

They also enjoyed working with Polywood.

“Polywood was friendly and communicative,” said Petersen. “They gave us a realistic budget and easily facilitated purchases.”

The feeling was mutual.

“We have enjoyed working with the team and have appreciated their communication and updates throughout the process,” said Hochstetler.

“We have been running the tester to get familiar with it, and it has been just as described by the team. We are confident it will be able to provide us with the data we need during the design and testing process of our products.”