Filtering oil with a filter cart has been useful for maintaining target ISO contaminant cleanliness codes. We’ve found that placing a magnet in the filter cart and/or unit, near the inlet before the pump, is also beneficial for removing wear debris and for routine inspections. Place the magnet in a location where it can't interrupt oil flow and ensure the magnet is strong enough to remain in place.
Inspections of the magnet should be compared to the oil sample because oil analysis results may be better due to the magnet capturing metal. If multiple pumps/bearings feed into one lube unit, use a magnet for each return line to determine which one may be wearing out. Consider wearing leather gloves to protect your hands from sharp metal fragments when cleaning the magnet.
The pictures below are from a four roll vertical mill with a 1,000 gallon reservoir. The magnets are in the sight glasses for the return pumps for each of the four rolls. They are about the size of a quarter, 3/8” thick and silver in color. They appear black due to the metal built-up. The sight glasses can be opened and the magnet can be removed and cleaned.
