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A Review of Press-Maintenance Procedures

(February 2011) posted on Tue Feb 22, 2011

Find out how simple preventative maintenance can keep your presses running at peak levels and head off costly downtime and quality issues.

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By Rick Fuqua

Machines using motors with brushes should be monitored. It’s a great idea to inspect these brushes every six months and write on the motor the last date it was checked. When these brushes wear out, they will ruin the motor quickly by allowing arcing to occur on the armature of the motor. Most motors cost more than a few hundred dollars, so check these brushes regularly.

Housekeeping is important, especially for control cabinets or motors that rely on a certain amount of cooling for their performance. Heat can cause failure, and if cooling weren’t so important, the manufacturer would not have installed a fan. Keeping fans clean and working on motor enclosures and control cabinets is essential. Louvers are sometimes used in addition to fans to allow for passive air flow should the fan stop working. Dirt and atomized spray glue have an easier time working their way into these open designs. Clean the components and enclosures periodically.

Fewer machines use hydraulics these days, save for shock absorbers or linear decelerators. These devices use the flow of oil within the unit itself to create a resistant force that can be used to slow down or dampen the speed of the part that comes in contact with the shock. Oil flows through or out of multiple orifices in these devices as the plunger is pushed in. As the plunger is forced in, the number of escape holes is reduced, which causes a buildup of backpressure. The effect of backpressure goes unnoticed when the plunger is pushed in slowly because, in this instance, the oil has plenty of time to escape; however, when the plunger is depressed quickly, you should notice the resistance quickly and that it builds as the plunger goes in. Some of these devices are equipped with an adjustment to increase or decrease the port size of the holes within the unit, thereby changing the overall force/speed effect.

Checking the performance of these devices is crucial to the performance of the machine movements they are used to control. Aside from making adjustments to shocks for changes in temperature and changing force ratings, the unit may need to be replaced after awhile due to failure. If the shock is not providing the required impact reduction, then excess wear will occur.


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