Motion System Design

Producing plastic in the cleanroom

Using robotics alongside injection molding machines (IMM) is a challenging task, especially when parts must be produced under cleanroom conditions so often required in food and pharmaceutical applications. Absolute precision regarding timing and movement of parts is critical, leaving little room for error. When Rexam Pharma GmbH, Germany, needed an automated system for manufacturing plastic containers in a class 100 cleanroom environment, they turned to automation specialist Geiger Handling Systems AG of Switzerland.

The manufacturing process for the containers uses two parallel IMMs. Geiger chose two RX130 robots from Stäubli Corp., Greenville, S.C., because the machines were specially designed for cleanroom applications. Assembly of the molded parts involves joining covers to containers within the cycle times of the IMMs. For the pilot phase, two injection molding tools were used, each with four cavities. For subsequent production, 32/64 impression molds were used. The molding cycle time of the first mold was 23 seconds, with 13 seconds for mold two. A takeout interval time of 2 seconds for removal of the four containers and their matching covers meant that operating sequences of both robots and vacuum grippers had to be extremely precise.

Robots remove all molded parts in one operation before the mold immediately closes. The two robots then transfer molded parts to the work cell's center where covers and containers are assembled. When assembly is complete, one of the robots places assembled containers on a conveyor belt, which takes them to a class 1,000 cleanroom for further processing. Gripper systems are made of lightweight steel and the presence of parts is checked with vacuum switches.

The combination of robots, vacuum gripper systems, a vacuum supply system, and monitoring equipment ensures reliable and accurate handling of the pharmaceutical grade plastic parts. For more information, visit

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