With ABB robots and a new material from 3M, Esys Automation claims it is now bringing automated processes to wheel balancing

In tyre and wheel assembly there aren’t a lot of game-changing advances you can point to that have completely altered the paradigm for how wheels get fastened to cars and trucks at the factory. “Indeed, wheel balancing isn’t something that gets a lot of publicity,” comments 3M’s Scott Taylor, “but when it does you can be sure it’s for a good reason.”

Taylor, who is automotive market technology manager for 3M, has reason to be celebrating: it’s 3M’s new wheel balancing material that finally enabled the full automation of a notoriously costly bottleneck in automotive assembly. Along with Esys Automation, the two companies claim to have developed a simple, fast and compact system that relies on robots such as ABB’s IRB 140 to reduce wheel balancing cycle times while increasing ride quality for the endconsumer. “3M’s product was really the enabler for us,” says Chris Marcus, CEO of Esys, the company responsible for developing the AutoW8t wheel balancing system. “Their revolutionary metal-impregnated polymer tape gave us the ability to bulk store balancing material and feed it to a line. Once we saw the product and the idea was pitched to us from 3M, AutoW8t was an obvious solution.”

Bottleneck solution

Traditional clip-on weights are pounded onto the flange of the wheel by hand, introducing cracks and chips that can easily lead to corrosion. The process is painfully slow – at least in automotive manufacturing terms – and has always been one of the biggest bottlenecks in the assembly plant. Automation of this process has long been considered one of the ‘Holy Grails’ of bottleneck reduction.

“The industry has been trying to automate wheel balancing for 15 to 20 years,” says Taylor. “In some cases they were getting close, but the problem lay in the way the traditional wheel balancing materials were coming in. Traditional weights were supplied in discrete increments made from materials that couldn’t be cut. 3M’s new material gave them a product that could be easily trimmed and not have any issues with corrosion.”

In addition, with the ban on lead weights, the industry has moved to steel which isn’t as malleable as the old weights. While better for the environment, the trickier-to-handle steel weights have required the car makers and suppliers to inventory a tremendous number of parts to conform to the large variety of weights and wheel dimensions required. Even then the wheels can only be balanced to within one quarter ounce – far from being a true balance. In addition, as the manufacturers move towards a sleek, flangeless look, the question of where to clip on the weights becomes a problem.

Compact system design

With the AutoW8t robotic system all of these issues in the traditional wheel balancing process have been dealt with. Using compact 181-pound rolls of the conformable, polymer composite, corrosion-free, adhesive balancing tape, the AutoW8t system feeds the material from a central storage location to a 1.0-meter x 1.3-meter cell.

“In the manufacturing world that kind of footprint is tiny,” says Marcus. “We’re able take this little system and slide it in right behind the balancer in an existing plant without much modification. In addition, our feed system allows the 3M material to be loaded in a safe location in the aisle and then fed overhead to the balancing cell to avoid any need for workers to enter potentially hazardous and space-limited areas.”

While the feed system and balancing material are news in their own right, it’s inside this compact cell that the main automation developments can be seen. The polymer tape is fed to a specialised magnetic gripper placed on the end of an ABB IRB 140 robot. The gripper receives two precision-cut strips of material and then, using calculations performed by the balancer at the balancing station upstream, precisely places the adhesive-backed weight strips on the interior rim of the wheel. The result is increased quality, reduced waste and lower costs – not to mention increased throughput and improved appearance.

Reduced cycle times

“When we first started using 3M’s material we created a semi-automated system without robots,” says Marcus, adding that they quickly realised the biggest benefits would be from a fully automated system using a robot applicator. “An average operator in the semi-automated system might be able to apply one weight in 15 to 20 seconds, while the robotic applicator can apply two weights in 10 seconds.” In an industry that jumps when it hears of improvements in the order of 1 to 3%, the ability to reduce cycle times by more than 65% is a significant advance. In fact, this accomplishment earned both 3M and Esys a 2012 PACE Award.

“It’s rare in our industry to get recognised for anything, so we certainly didn’t expect a PACE Award,” says Marcus. “AutoW8t is a dramatic change to the paradigm of tyre and wheel assembly. Now that a few major manufacturers have implemented it, what we’ve found is that all of them are moving quickly to do trials and tests and get the equipment into their plants. I see our AutoW8t system as the way all wheel balancing will ultimately be done by every manufacturer if they want to remain competitive.”