01 April 2007
As the final stage in its upgraded valve guide production line, the company has recently installed an automated product inspection system from GB Innomech. It checks 10,000 components per hour and has an 80% Overall Equipment Effectiveness rating.Dan Maynard, technical director at Innomech, said: “About 90 million valve guides pass through the inspection plant every year and quality is paramount. The previous machines were slow and becoming increasingly maintenance hungry, and had therefore become a bottleneck in an otherwise highly efficient manufacturing line. “We found the two major rate limits on the existing machines were that all components had to be orientated the same way round (ie with all ‘heads’ pointing in the same direction) and that measurements and checks could only be carried out on stationary parts so the carrier belts were constantly stopping and re-starting.”The Innomech machine can measure and check components on the move, irrespective of orientation. The valve guides are firstly transferred from a centrifugal bowl feeder into the machine and an initial DVT Legend Series smart camera checks their lengths, to within 1 mm, and filters out any mixed components from an earlier batch. A pusher device turns components onto their sides before transferring them onto a flighted belt so that their end faces are visible.Five further cameras then inspect each component, as if it could be either way round, and measure it using two Keyence laser micrometers. The results are passed back to a Siemens S7-300 PLC, which also provides overall machine control, for tracking through the system. The system captures eight analytical images per component (equivalent to 22 images per second), a further 68 measurements are performed, for example to position a component on the screen. As a final step, a ‘flipper’ device guides components into polythene bags or into a waste hopper depending on their status.The machine incorporates three levels of networkingASi for actuators, sensors and safety systemsProfibus for servo drive controlEthernet for data exchange between HMI, PLC and camerasGuard interlocks achieve EN954-1 Category 4 rating using the 2-wire ASi network rather than traditional hard-wired systems. To change batch, the operator selects the new part number from a menu driven, touch-screen HMI and is then guided through the auto calibration sequence. Total changeover should be five to ten minutes. The main screen also displays performance data, diagnostics and correction routines.If a malfunction occurs, the machine’s fail safe position is to reject all components.With previous machines changeover times could be up to an hour and a half long. Operators needed six weeks training compared to the day recommended by Innomech. The system also incorporates a Westermo modem and router to allow remote diagnosis, monitoring or modification of the PLC, HMI and camera systems.Phil Bailey, operations director at Federal Mogul, claimed the machine had transformed speed, efficiency and quality. He said: “We have increased our first time yields, reduced the number of machine operators, and cut our work in progress while at the same time securing our margins and maintaining a lead in what is an intensely competitive and tough market. “The new system also provides us with comprehensive, real time data to further improve our overall business efficiency”.
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