User login

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.

click an image below to view slideshow

By Rick Fuqua

Oversized breakers will not show up as a problem until the time comes when they should trip to protect your equipment and don’t. Undersized breakers are a nuisance, but do not be tempted to replace them with oversized breakers. Check your fuses regularly, and be prepared to replace any that may be damaged in a short. Keeping properly rated extras on hand keeps downtime to a few minutes and cuts down the temptation of using the wrong size just to keep production going. You may not remember to replace these quick fixes later. Presses often take fuses that aren’t available from the local hardware store.

Other power-related service issues that top the list include batteries used to backup computer memory. If your press’s PLC uses a battery for memory, then waiting until that battery fails before you replace it will require you to reinstall its software. Imagine the productivity you’ll lose when you send the PLC back to the manufacturer.

Safety systems often fail because they’re exposed to a lot of abuse. Jumping safety systems for any reason other than troubleshooting is a bad idea. When your safety system fails, you should immediately find and fix the problem. Depending on the system and machine used, the diagnostics for finding a short can be frustrating but well worth the effort.

Switches are often the culprit of machine failure. Switches may fail at any time, leaving you down one printhead or an entire machine. Having one or two switches on hand that are common to your machine is a good idea. Like many electrical parts, a physical inspection does not reveal any signs of looming failure. One day they are working; the next they may not. One exception is the leads that run to the switch. Wear and tear can lead to a short that will often ruin the switch entirely. Some proximity switches have short-circuit protection, but when this feature is lacking, one wire touching the other leads to complete failure. Proximity switches used on printheads often fail due to mechanical issues such as the leads getting tangled with a moving part. Normally this causes the squeegee-floodbar carriage to stop at one end or the other and refuse to cycle back. The switch may fail open or closed.


Did you enjoy this article? Click here to subscribe to the magazine.