A manufacturing engineer here has asked if anyone has experience with sticking nozzles on Universal 4791 (Sanyo TCM 1600) chipshooters.  Typically, the problem occurs after one or two weeks of continuous operation.  The nozzles hang, and will not drop in time when the machine is running at full speed.  Once the nozzles are removed and cleaned (wiped down with IPA on a clean cloth), the problem goes away for another one or two weeks.  

While the one or two week P.M. is not unreasonable, there are machines running high volumes where this happens every 3 - 4 days, and this is a problem.  Ultimately, the machine bypasses the stuck nozzle and runs at reduced speed.

Questions:
1.  Is this a common experience with these machines?
2.  Does anyone have better results with a different cleaning method?
3.  Has anyone tried a thin film lubricant, such as wiping with a silicon - impregnated cloth?  (We can think of lots of objections to this.)
4.  Is there any benefit to changing out a nozzle after a certain number of estimated cycles of operation to prevent future sticking problems?

Any input is much appreciated.

Bruce Tostevin
Benchmark Electronics
Hudson, NH

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