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Zimmerman CNC machine with lubrication alarm

Had a problem the other day with a Zimmerman bridge type CNC machine tool. The machine utilized a grease lubrication system for it's linear guides and ballscrews. The Zimmerman had a lubrication alarm that came on after about 15 seconds after the alarm is cleared.

To determine what was the cause I had to figure out how the system worked since I had never worked on a zimmerman machine tool before. First I made sure the machine had enough grease in the resevoir and checked that the pump cycled on. After that I had to check to see the grease was being forced through the system. To figure this out I cracked the hose loose and grease flew out. Next I had found a valve in the circuit next to the pump which if it turns on applies the grease to the X axis. If the valve is left unenergized the grease goes to the Y and Z axes. Once I determined this I had to find out where the pressure switches were located to see if they were working properly. I checked the pump to see if it was built in which is often typical. However since it is a bridge bill they seem to have them as close as possible to the place of discharge to make sure grease makes it to the end. I ended up finding one under the back left side of the X axis and after some searching found another one on the very top of the column under a sheet metal cover. Since the X axis grease switching valve does not energize at this time I decided to manually push the valve to divert the flow to the X axis and watch the LEDS on the switch to see if the pressure switch actuated. It did. So this test determined that the grease pump was capable of producing enough pressure and that there were no leaks in the grease line on the X axis. The pressure switch on X was a different type of switch compared to Z axis but I believe it was still a good way to at least check that the lube pump could create pressure. Next I checked all the Y and Z axes for leaks visually in the lines, but this was very hard to do since there were so many covers. So the next thing I did was check the pressure switch for the Y and Z axis with a meter. It did not switch. I also ran the pump and cracked a line and it seemed as though there was plenty of pressure. At this point I determined it must be a bad pressure switch.

Replaced the switch and problem was fixed.