Texas Tech University

Mechanical Engineering Students Create Device to Help Prevent Plastic Contamination During Cotton Harvesting

Amanda Bowman

December 21, 2018

(VIDEO) The students worked on the device during their senior Engineering Design I and II classes.

Money, T-shirts and Q-tips – these may seem like a random assortment of items, but they do have one thing in common: cotton. U.S. paper currency is 75 percent cotton. Many T-shirts are made entirely or mostly from cotton. The fluffy ball on the end of a Q-tip? Yup, that's cotton.

Texas is the top producer of cotton in the U.S., producing almost 9 million bales in 2017. According to the Plains Cotton Growers, Lubbock and the High Plains region produce two-thirds of Texas cotton and cottonseed, 25-30 percent of U.S. cotton and cottonseed and 3-5 percent of the world's cotton and cottonseed.

Since cotton is such a vital crop to Lubbock and the High Plains, it's imperative to maintain not only the quantity, but also the quality of the cotton it produces. However, there is a major issue: contamination.

To help solve this problem, Gregory Holt, a cotton researcher for the U.S. Department of Agriculture, reached out to Texas Tech University's Jeff Hanson, an instructor in the Edward E. Whitacre Jr. College of Engineering's Department of Mechanical Engineering. Hanson, who teaches mechanical engineering Design I (ME 4370), tasked his students with tackling this challenge, which also would take them through their Design II (ME 4731) class.

engineering students
The students working on the project.

The group of senior mechanical engineering majors who were tapped for the project include Alexander Brewster, of Grapevine; Brett Brorman, of Big Spring; Brian Kwok, of Winnie; Zack McCord, of Plano; Andrea Ruiz, of Bogota, Colombia; Toby Sanders, of Milano; and Cody Striker, of Edgewood, New Mexico.

"The need for this project stems from the fact that the U.S. gets a premium for its cotton because it's some of the cleanest cotton in the world," Brorman said. "Plastic contaminants are infringing on the premium cotton farmers get, so the USDA really wants to get rid of the plastic completely.

"Dr. Holt and the USDA came to us with the idea of addressing the problem with harvesting. They wanted us to either keep the harvester from picking up the plastic or develop a way to separate out the plastic. We went for the idea of keeping the harvester from picking up the plastic at all."

Third time's a charm

The USDA had previously presented the contamination problem to two other schools before reaching out to Texas Tech. Though the others had inventive ideas, the group at Texas Tech has been the only one to come up with a feasible solution.

"The previous groups came up with other solutions that are more indirect methods of dealing with the problem, like mapping the cotton fields with an unmanned aerial vehicle (UAV)," said John Wanjura, a cotton production and processing research agricultural engineer from the USDA Agricultural Research Service. "But the mechanical engineering group at Texas Tech was the first one that came up with something that could be bolted on the harvester and actually tested."

That's not to say that the group at Texas Tech, informally named Double T Cotton, didn't come up with far-fetched ideas when they first came together.

"At first, we thought about arms; we thought about rollers; we thought about a lot of different things," Ruiz said. "But it ended up being that everything was either just way too slow or way too complicated for us to build, so we thought of something kind of like a garage door mechanism."

After some trial and error, the team found the answer.

"As soon as we realized the garage door was too slow, we ended up coming up with something that would have fewer parts so it would be faster," Ruiz said. "It's basically a skid plate that covers the header of the cotton harvester so plastic doesn't get into the harvester. We had to build something simple because we manufactured it ourselves, which was pretty intense. A linear actuator powers it, and that's how the plate moves."

harvester plate
The plate works by pushing down the cotton to avoid plastic contamination.

The group's device works by pushing down a row, or rows, of cotton that are contaminated with plastic, thus avoiding the trash from being picked up by the harvester.

The students weren't able to use heavy materials for the device since they couldn't add too much extra weight to the harvester.

"We're using a little bit of steel, but it's mostly aluminum due to its light weight and durability," Brorman said. "Then we're using a plastic that's already used on harvesters because it's durable and, in the future, if they want to mold our part, they have the ability to do that."

Unlike the previously proposed UAV field mapping, where data could become obsolete if not acted upon quickly, the device the students created is instantaneous.

"The device is basically a real-time system," Wanjura said. "You have the ability to see the cotton from the harvester, so you're seeing it right when you need to see it. You've also got a control, whether it's automated or just a manual control, to actually go down there and block one particular row unit or multiple row units off from allowing the plastic materials from getting into the cotton."

Future plans

Though still in its early stages, the plastic plate developed by the Texas Tech students could potentially end up on cotton harvesters in the future. In the meantime, Holt already is showing it off to other people in the agriculture industry.

"Dr. Holt is really excited about it," Brorman said. "He told us he's been showing our design around. He travels around the world to places where harvesting and agriculture are prominent, and he's been showing our design to everybody because he thinks it works and might actually solve their problems."

Wanjura shares Holt's enthusiasm in regards to the team at Texas Tech.

"Texas Tech is a great resource to us," Wanjura said. "The students were great. They were super-intelligent people to work with. They have great engineering skills, and they have bright futures ahead of them. From our standpoint, it's a great partnership to work with Texas Tech and all the engineering departments there, not just mechanical.

"Being able to tap into that resource of young, creative minds is something that's greatly needed in our industry, especially as we move into more computer control, automation and the newer technologies coming out. It's going to take a lot of these younger minds to help harness the value out of that and get things going."

What Ruiz enjoyed most about working on this project was her ability to use her other skills along with engineering, something she didn't think was possible.

"This project definitely has made me realize that I do want to do design work and also manufacturing," Ruiz said. "It's impacted me in a way I didn't think of because, at first, I thought I just wanted to do a lot of programming. Then I realized, now that I've done all this design work on the project, it's been very creative. I really like using my creativity for my work."

Brorman hadn't considered going into the agricultural industry, but this project showed him it could be something worth pursuing.

"This has definitely made me think about agriculture a lot more," Brorman said. "I didn't really think about pursuing that industry before, but it's definitely made me see the engineering aspects of agriculture."