Retreading is absolutely crucial to the economics of the trucking industry. The process involves re-molding the tread of truck tires onto the casing after it has begun to wear down. It’s a common practice that significantly increases the life of a tire and saves both money and material. Until recently, retreading was carried out on commercial vehicles, buses, airplanes and heavy duty trucks, however it has now become a more common practice with passenger vehicles. The process of retreading is highly regulated in most countries, but it is still met with criticism and safety concerns, with tire failures often being attributed to retreading. In fact, the majority of tire failures and blowouts are not a result of retreading , as much as the under- or over-inflation of the tires, road hazards, bald tires, or overloading. Truth is, a quality retread will perform as well as a new tire, which is why retreading use is widespread in commercial transportation.
The real concern with retreads actually has to do with the condition of the casing. Casing defects can be difficult to spot during retreading. The overall reliability of a retread tire is dependent on the ability to inspect the tire casing and accurately determine if defects exist.
Oldies but Still Goodies
To maximize safety and reliability and minimize costs, it’s crucial to make sure that each carcass is structurally sound before retreading. There can be as many as 16 steps in retreading a commercial tire: a worn tread is buffed away and a new tread bonded on in a process similar to the manufacture of a new tire. And for the roughly 850 retread plants throughout North America, the process is essentially the same – affixing a new tread requires heat, time and pressure.
Surprisingly, tire retreads save oil, and not just in the increased efficiency of the vehicles they’re mounted on. The manufacture of a new medium truck tire requires about 22 gallons of oil. But it requires only seven gallons to retread. That adds up to hundreds of millions of gallons of oil saved in North America alone. It also saves space in landfills, saving those millions of tires from the landfill and helping them last thousands of miles more than their first tread.
For commercial fleet managers who buy thousands of tires every year, the benefits of retreading are staggering. Many aviation organizations — both commercial and military — are committed to retreading aircraft tires. In fact, 80 percent of aircraft tires in service in the United States are retreads. Like truckers, construction companies, farmers, and passenger car owners, aviation organizations purchase retreaded tires to save money without compromising safety.
Trucking fleets have begun to factor retreading into their budgets. Instead of having to budget for an entirely new tire (which can run hundreds of dollars), companies can expect a tire to be retread two or more times.
Expectations are that worn carcases will be retread two or more times before being retired (no pun intended!), instead of factoring in costs for an entirely new tire, which can run in the hundreds of dollars. Today, in North America, there are as many retreads on the road as there are original tires.
The Better Treader Checker
It’s essential for professional retreaders to adhere to stringent industry standards at each step of the retreading process. Most retread plants are franchised, licensed or otherwise consulted by or affiliated with major manufacturers who provide technical assistance and standards to ensure a reliable product. That’s where machine vision comes in. Casings need to be checked before they’re retreaded to make sure they are worth the investment. They are then checked during the process to ensure the retread is done correctly.
G2 Technologies Inc. is a system integrator that specializes in the automated inspection of a wide variety of materials, particularly for web applications. Recently, one of the world’s largest tire manufacturers came with a big request: upgrade their vision systems used to check tires across their retreading facilities. The tire manufacturer’s aging cameras were not working properly and replacements were no longer commercially available. G2 facilitated the upgrade of the systems used in the retreading facilities to ensure that only sound, inspected tire casings were being retreaded.
Large commercial tires are not ideal imaging subjects. They are dark, thick, and typically imaged under imperfect conditions. Checking to see if each tire casing is damaged, or defective in some way, is not easy. Defects and tire layer separations exist on the millimeter level. The moving material, challenging lighting, and high rate of speed needed to make the plant efficient push the vision system to its limits.
G2 Technologies’ solution was to upgrade the inspection system with the Teledyne DALSA Genie Nano camera, providing improved performance in a smaller form factor. The new camera was not only much smaller than the camera it replaced, it also offered higher resolution and a significant speed bump.
As big as commercial tires are, there is still limited space inside a tire and that leaves very little room left for a camera. Full size cameras, even when they do fit, require very tight tolerances to make sure there is no damage to the systems. Clearly a smaller camera was required, but one that didn’t compromise on performance, in terms of resolution or speed. Otherwise, all potential efficiency gains would be lost.
The resulting system produced significant advantages with the new cameras. Because the vision system images are checked manually, the new, better resolution meant that checking tires would be both more accurate and easier to accomplish. The higher resolution offered much better coverage (10 times the number of pixels per defect) of even the smallest defects, and even allowed the operator to zoom in on relevant parts of the total image.
Innovation Keeps Us Looking Forward
When developing the right system, performance and ROI are paramount, but industrial systems need to deliver much more. Simplicity⎯and the reliability it provides⎯is a critical factor. The fact that a single GigE cable could deliver the Genie Nano’s data feed meant the risk of failure was much lower. “Exposed cabling is the biggest problem for systems,” explains Craig Borsack, P.E., president of G2 Technologies.
With technology improving so quickly, it’s certainly expected that speed and resolution will increase. System builders will be able to deliver more efficiency and higher precision. And if those improvements can continue to offer reliability improvements through smaller cameras and simpler systems, then we’ll keep seeing new and better systems.