Trigger-happy paint cans

In the mature spray-paint market, packaging and product-use innovations are just as important as the product advancements themselves. Rust-Oleum Corp., a worldwide leader in protective paints and coatings for both the home and industry, recently launched its new Universal all-surface spray-paint line that combines innovation and product advancements.

A key feature of the 12-oz spray cans is the revolutionary cap that employs a user-friendly and more ergonomic trigger that makes the product easier to use. The new cans can spray paint in any direction, even upside-down, and the easy trigger actuation eliminates finger fatigue. The caps also include a drip guard to prevent paint from getting on the user's fingers.

Rust-Oleum's existing capping machines were not equipped to handle the unique needs required by this packaging innovation, so the company selected Haumiller Eng. to customize a continuous-motion system to apply and orient the special cap for its new packaging.

Trigger alignment is critical

A critical requirement was that the new trigger must properly align with the can's label. Haumiller addressed this through a novel assembly process that orients each cap precisely at high speeds.

As Rust-Oleum was developing the cap and the can graphics, the Haumiller team began adapting the Haumiller 4600 container/cap orienting system to work with the cap's unusual design. The custom system, which uses machine vision to detect a black eyemark on the label to help consistently position the caps, can run more than 200 assemblies/min. By using a continuous-motion system, the tooling never loses contact with each component, and thus ensures perfect alignment, Haumiller says.

Haumiller's technology allows Rust-Oleum to optimize the assembly process, maximize productivity and increase up time in production, while offering the most consistent performance possible.

“It is difficult to find new ways to generate growth and differentiate a product in such a competitive, mature market,” says Russ Holmer, president of Haumiller Eng. “But I think we found a way to make Rust-Oleum's vision a reality and add value to its already superior product. We were able to reduce the risk of such a complex project and take the can't-be-done concerns out of the equation for them.”

Tooling for cans and caps

In production, filled aerosol cans with a valve stem on top are delivered on a conveyor to the continuous-motion, 12-pocket orienting machine and enter a starwheel where two levels of tooling grip the can—one near the top and one near the bottom. A photo eye detects the presence of cans on the conveyor, and the machine stops if cans are not present. The cap assemblies are fed oriented with their open end down with the trigger trailing from a hopper to a vibratory feeder. They travel down a track and are picked up by grippers in the infeed starwheel just above the cans.

The cans and caps are then transferred to the main rotating turret. The cans enter the pockets, while the caps are transferred to a cap race. Each of the 12 pockets in the main turret is equipped with clips and a stepper-driven rotating stage with magnets that spins the can at 120 revolutions/min. A sensor detects the registration marks on the cans.

Rust-Oleum wants the trigger and label on each can to be aligned exactly the same on every can, so the sensor tells the control to stop the can spin when the can is aligned properly to receive the cap.

The caps on the cap race are also spun as the turret rotates, until they reach the proper positioning with the trigger trailing. At this point, clips lift the cap off of the cap race, which ends at this point, and stroke down to apply the cap to the can.

As the turret continues around, an air-cylinder-actuated assembly cam applies 100 to 200 lb of force to finish applying the cap to the can. The cans then travel through an exit starwheel onto a take-away conveyor. Cans without caps or missing triggers are deflected off the conveyor after they leave the machine.

To ensure that a cap is never stuck in the machine, a pin extends through the upper tooling as the rotating turret reaches the can exit point to release a cap if one is present, and an air blast blows it into a chute leading to a basket on the floor.

“I always admire the Haumiller team for looking at a problem logically and figuring out how to solve it,” says Bill Tucknott, project engineer for Rust-Oleum. “We knew it would be a tricky product launch, and I'm glad we chose Haumiller.”