The Issue
Birmingham-based health products manufacturer Cuxson Gerrard & Co Ltd had a major breakdown on one of two machines making sticking plasters. I responded to the call when arrived at the machine, one I had not seen before, I found it was more than 10 years old and the faulty part was obsolete and no longer available. The machine had been designed and made in-house by the Works Engineer who had since left and records were sketchy. It incorporated a number of servo drives, one of which was a linear motor supplied by Linear Drives Ltd, of Basildon, used for indexing the continuous web of sticky-backed material through the punch and die set which punched out the plasters.
The linear motor comprises a stainless steel tube packed with disc magnets, running through the centre of a thrust block fitted with three integral phase coils that moves relative to the motor tube when the coils are energised in sequence. The motor was powered by a Linear Drives brushless servo amplifier operating in force (current) control mode, to control the tension in the web, and its operation is controlled by a motion controller made by German company Jetter GmbH, for adjusting the length of the indexing stroke which in turn controls the width of the sticking plasters.
The Solution
The motor coils had burnt out, causing the amplifier to fail. The first problem was that whilst Linear Drives still made an almost identical motor that could be fitted as a direct replacement, they no longer made the amplifier, having been taken over by American automation equipment company Copley Controls Corporation which chose to supply its own range of brushless amplifiers. The next problem was to integrate the new amplifier with the Jetter motion controller, which necessitated adjusting the amplifier settings. The problem was made more difficult because Jetter no longer had technical support in the UK. However, I was able to master the problem and within three days had commissioned the new linear motor and put the machine back into production. Ironically, Cuxson Gerrard’s sister machine also failed within a few weeks of the first with exactly the same fault. This time, I had it running again within
three hours of fitting the replacement motor and amplifier.
My value to Cuxson Gerrard lay in:
- Swift response to their requests for breakdown assistance
- Identifying the problem and finding a viable solution
- Specifying and sourceing alternatives to replace faulty components that had become obsolete and were no longer available and impossible to repair
- Making the necessary mechanical alterations to fit the replacement parts
- Using my programming skills to understand enough about the unfamiliar control system to be able to integrate the new equipment and make it work
- Completing the work in the shortest time possible
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