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Keywords Automotive components industry, Automation
When the Cummins Engine Company sought a new control system for an automated circlip insertion machine on one of its engine assembly lines, it commissioned automation specialist Wearside Pneumatics, a member of the Festo Premier Stockist network, to handle the project. Wearside had previously developed a number of electro-pneumatic control systems for the engine load testing cells at Cummins' Darlington engine plant, as part of a highly successful system upgrade.
The circlip insertion machine is installed on the B series diesel engine assembly line at Darlington. These engines are produced in 3.9L four-cylinder and 5.9L six-cylinder versions, and are widely regarded as industry workhorses, being used in applications as diverse as medium-sized trucks, fire pumps and generator sets (Plate 2).
Designed to fully automate a complex assembly operation, the insertion machine takes partly-built subassemblies containing pistons and con-rods with loose gudgeon pins, and applies circlips to either side of the piston. Part of the process involves removing pre-fitted bolts from each conrod before the circlips are fitted. The machine is a dual-stage system - using a total of 16 pneumatic actuators - with fully replicated functions, enabling one half to be loaded with new components while the other half is handling assembly operations, to maximise throughput. The machine performs six assembly operations on each six cylinder engine, and with its original control system had a cycle time of 200 s, giving a throughput of just over 18 engines per hour.
The circlip insertion machine has performed impeccably ever since it was installed. However, after some 18 years, its control system was...