Palletizers Paint a Picture of Efficiency

Kelly-Moore's robotic palletizer has helped reduce line changeover time.

With more than 165 local stores, Kelly-Moore Paints provides paint and related products to contractors, commercial and maintenance accounts, and do-it-yourself consumers. The company maintains two facilities - in California and Texas - manufacturing and distributing nearly 15 million gallons of paint per year.

Kelly-Moore has a strong employee safety focus, but it still needed to address hand palletizing of products weighing up to 70 pounds and production flow inefficiencies. Ultimately Kelly-Moore chose Intelligrated to engineer a robotic palletizing system that fit its needs in a scalable way.

The Kelly-Moore manufacturing process involves four lines: two lines handling smaller, conventional gallon and quart paint cans; and the other two handling larger, five gallon pails. It was decided that two robotic arms would meet the palletizing rates that Kelly-Moore required. In this case, the Alvey robotic palletizing system used robotic arms sourced from Motoman.

Unwrapped trays of quart or gallon paint cans presented an early challenge for the end-of-arm tool designers. The solution demanded a tool that could pick up configurations of 2×2 gallon and 3×3 quart paint can patterns, and their respective loose cardboard trays. Kelly-Moore went with an end-of-arm tool with an additional vacuum arm specifically for the cardboard tray. Working with Tepro Machine & Pac System and its line of lifting tools, the final design lifts the cans and secures the tray with a separate pivoting vacuum arm that descends as product is moved to the pallet.

The five-gallon pails posed their own engineering challenge. A two-inch diameter tinting port on each lid that allowed customers to tint the paint in the store could not withstand a vacuum. The solution was end-of-arm tooling with a custom-designed ring within the vacuum plenum to prevent the flow of air from pulling out this port. The pails would then be lifted three-at-a-time and palletized in a nested configuration.

Once the pails are filled and sealed, they are conveyed via 15 feet of zero-pressure accumulation conveyor. Zero-pressure accumulation is critical with a circular product, like paint cans or pails, where any line pressure would be concentrated at the point of contact between adjacent pails and product back ups could create a jam or push the pails off of the conveyor. The heavier five-gallon lines are equipped with escapements to position the product in a precise location to allow the robot to pick them up in groups of three.

Based on Kelly-Moore's original specifications, the system design did not call for the robotic palletizer to handle pallets. However, it was determined that the robot could handle the empty pallet placement at the build positions without significantly affecting the speed of production. This design change alone saved Kelly-Moore $25,000.

Both robotic arms repeatedly pick and place cans or pails from the infeed conveyors and stack them sequentially on the waiting pallets. Multiple layers are built on the pallet until the load is complete. It is then conveyed on a chain-driven live roller pallet conveyor to a Lantech stretch wrapper. “Before, we were securing our pail pallets with rope,” says plant manager Keith Hussinger. Key to this system is the ability of the palletizer to accommodate quick line changeovers.

The system was installed and delivered during Kelly-Moore's off-peak season in early 2009. Over the next year, the improved San Carlos facility experienced impressive results, including a 76% return on investment in labor time, Hussinger says. “We were able to cut out almost all overtime, but still fill our orders. Additionally, our main goal of increasing worker comfort and safety was met, as our lost-time accidents decreased from 23 in 2005 to five in 2009.”

The automated end-of-line system has enabled the line to run at an even pace throughout the day, as the breaks required by heavy lifting from the old manual palletizing system were eliminated. Line changeovers, which used to take 45 minutes, now take only nine minutes.

This article is based on a case study provided by Intelligrated, a Cincinnati-based provider of automated material handling solutions.

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