The Manufacturers Association for Plastics Processors announced winners of its Innovation Award in late August. The contest, the third for MAPP, focused on automation. More than 250 industry professionals voted on 22 submissions.
First place was awarded to Intertech Plastics Inc., a Denver custom molder and MAPP member that boosted its presence in medical molding four years ago by acquiring Image Molding Inc., another Denver molder. Intertech won based on its presentation of how it automated a medical molding cell.
Faced with stringent demands for the medical component, Intertech built its own machine-side, automated work cell to take on the 3.2 million parts job last year. The cell relied on integrated process control and automated quality inspection to achieve zero defects.
Intertech President Jim Kepler said in a phone interview that the part is butterfly shaped with intricate features that cause asymmetric melt flow. The part has five living hinges and a locking tab at the far end that was key to its assembly into a medical product. Getting the tab right was critical. The job was difficult, with several pressure drops and spikes in the part and the threat of micro-shorts. Defects couldn't be detected with the human eye but the customer demanded zero defect shipments
"We added a visual inspection system with four cameras," Kepler explained.
"End-of-arm tooling presents the part for inspection to look for micro defects and distortion. We programmed the cameras by showing them good parts. If they saw a bad part it was rejected. If we got three rejects in a row we shut the system down to see what was going on."
The customer initially suggested Intertech add a second operator at the cell and increase quality assurance inspections to make sure no bad parts got shipped. But Intertech believed more automation was the solution rather than adding more production staff. Intertech felt automation would cut reject rates as well as decrease contamination in part handling and inspection. Automation would also lessen the risk of repetitive-motion injury.
Intertech used "watch dog" software for process control. The software monitors parameters during each cycle to make sure they are within limits and it communicates with the cell's automation to reject parts made outside the parameter limits. Each molded part from the four-cavity tool went into its own chute, allowing parts to be quarantined from each cavity.
The company spent about $66,000 to build the automated quality inspection cell in house. Return on investment was only 8.4 months just on labor savings alone because one operator's time was replaced by one-tenth of an operator's time.
Intertech also designed and built the manufacturing cell's end-of-arm tooling that features multiple gripper points and stabilizing features. Electronic part detection means the robot will alarm out and prevent mold closure if parts are not pulled from the mold correctly.
The company ran the molding cell with zero defects for eight months. Intertech's initiative earned the company preferred supplier status. Intertech replicated the technology to three additional work cells.