LU Assistant Professor: ‘Plastic, plastic everywhere, but why don’t we teach students about it?’

For young people today, plastic is so common and so freely accessible it seems like one of life’s little luxuries like a warm ray of sunshine or a cool sip of water — something to be appreciated in the moment and then forgotten. From their earliest memories, plastic has always been there as a faithful servant in the form of a lunch bag, a water bottle, a fork from the school cafeteria, crystal clear packaging around a birthday cake or a toy that provided a few moments of entertainment before being shoved in a drawer.

“Plastic is truly an amazing material which has transformed the way humans live, but part of what makes it so useful is the fact that plastic products can be sold for a very low cost,” said Dr. Robert Kelley Bradley, an assistant professor of Industrial and Systems Engineering at Lamar University.

Usually value and cost go hand-in-hand, but for plastic, part of its value is the fact that it has a low cost. That explains why young people can take this amazing material for granted, but why does our educational system take it for granted, too?

“The development of plastic has simply outpaced the development of science curriculum,” said Bradley. “What we think of as the standard science curriculum emerged from the space race in the 1950s. Science was a national priority and so was science education, but plastics manufacturing wasn’t that significant at the time. Leaders developing the curriculum knew about it, but it must not have seemed like a priority.”

Today, that omission still hasn’t changed, but the importance of plastic certainly has.

In a recent article titled, “Education in Plastics Manufacturing: Aluminum mold making and injection molding,” Bradley shared what he learned from teaching students about plastic manufacturing through hands-on experience with hobby-scale injection molding.

“As long as we have the idea that plastic is this thing that’s just always around, it’s going to be hard to understand its importance or to address the challenges of recycling it,” he said. 

Bradley’s work involves bringing hobby-scale injection molding into the classroom in order to demystify the way plastic products are made. 

“Injection molding is the primary way we get three-dimensional plastic objects,” he said. “Another option is 3D printing, but it represents a small fraction of the plastic products currently produced and it’s far too slow for classroom use.”

Due to the heat and pressure, injection molds are generally made out of aluminum using a computer-controlled milling machine.

 “It’s very easy to operate the injection molding machine itself, even older elementary school students can do it, but making molds is another story,” said Bradley, who has developed a guide for creating aluminum molds. “I really wrote it for myself; when I started out, I was teaching high school and I was awarded a grant to purchase the equipment, but I’d never made an injection mold before. I hope the guide will help other teachers who would like to bring injection molding into their classrooms but may be reluctant.” 

Since joining Lamar University, Bradley has had several groups of students successfully make molds for their engineering capstone projects.

“There are actually a lot of people out there with the skills needed to do this. Hobby injection molding machines run about $2,000 to $3,000 and hobby milling machines are about the same price; they’re affordable for most schools,” the assistant professor said. “All that’s really needed is one teacher or one person from the local community willing to learn how to make the molds. It’s a big deal for the students. When my high school students got to work with the machine, they were excited and it changed their outlook on plastics. I hope more students will get this opportunity in the future.”

The article by Bradley is published in the International Journal of Mechanical Engineering Education and the accepted manuscript can be accessed for non-commercial use for free.