The tire retreading sector applies new tread on 4.5 million tires each year. Mordor Intelligence projects that the global retreading markets will grow from this year’s $5.45 billion to $6.41 in 2028.
Although each of these tires represents a reuse of the majority of a rubber tire, on average, 9 pounds of material is removed from each tire. This results in a mountainous amount of waste. Chris Williams, professor of mechanical engineering at Virginia Tech, explained that retreaded tires are more resistant to rolling than new tires. This causes the trucks to use more fuel.
The university, in collaboration with Michelin and an ex-colleague now working at New Mexico, is developing 3D scanning and print techniques and materials to produce retreaded wheels that are less wasteful and roll better. Customers can then reap the economic benefits from retreading while not having to suffer as much.
The REMADE Institute is funding the $1.5 million, two-year project in order to improve retreading efficiency. The REMADE Institute is a public-private partnership established by the U.S. Department of Energy that is dedicated to accelerating the nation’s transition to a circular economy.
“We are really excited to undertake this challenging project, which integrates advances in polymer science and manufacturing including 3D scanning, 3D printing, and industrial robotics,” said Williams. “If all goes well, the resulting retreading technology could result in annual reductions of about 90 metric kilotons of tire waste and 800 metric kilotons of CO2 emissions across the retreading industry.”
The team’s approach will be to use 3D scanning technologies, new materials that can both be printed and resist the solicitations of commercial vehicle tires, as well as industrial robots that can print these materials only at selected locations around the used tires.
While today’s process removes the entire tread of the old tire, the Virginia Tech process would only remove the bad portions, adding new material in those places. The 3D-printed cushion rubber in these places is used to adhere the new tread.
The challenge is that the cushion rubber is a thick material that doesn’t flow well when it is printed onto the tire surface and it doesn’t cure quickly, so these were key areas targeted by the project, said Williams.
Williams, who has developed the 3D printing technology, is responsible for the development of the 3D printer. Tim Long, a recent transfer from Virginia Tech, has expertise in polymers that are being tested.
As 3D printers typically print flat surfaces while tires are round, the Virginia Tech Printer works its way around the tire target as it prints in order to create a curvy surface.
The team is now at the halfway point of their two-year project and has developed promising techniques and materials. In the next year, they will use these to make actual tires, and test them to determine their characteristics. Williams stated that “right now, our material shows the same performance as the traditional bonding Rubber”. “We can 3D-print it. That is exciting. And we just finished building our robot work cell with scanning capabilities. So we’re ready for year two, where we put all those pieces together.”
It is important to test the performance in real-world conditions of all these components. “Now we look at how well our printer rubber attaches to the old rubber and make sure the whole ‘sandwich’ comes together,” he continued. “The biggest test will be that we are sending some of our printed materials down to our partner, Michelin, and they’ll actually put them on a test track on a vehicle in the next year.”
The rubber will meet the road. “The lab results suggest this is good, but now we’ll do an actual test on an actual vehicle.”