By Jim Fitch
Machinery Lubrication Magazine
Let’s face it: Machines in industry are largely made of iron and steel. Ferrous metals both encase these machines and bear the brunt of most friction, wear and corrosion. Often, the most critical machine components, parts and surfaces are those that possess the greatest intrinsic strength and wear resistance. In more than 90 percent of the cases, these mission-critical components have iron-based metallurgy. Common examples include cams/followers, gear teeth, shafts/journals, rolling elements and raceways of bearings, pistons and cylinders, mechanical couplings, chain drives, screw drives, and rotors.
As machines age and wear, metal is lost to the lubricating oil or grease. The rate of wear is directly proportional to the growing ferrous particle population in our lubricants and filters. These mobilized wear particles pose even greater risk in causing collateral damage elsewhere in the machine. Common examples include particle-induced abrasion, surface fatigue and motion impediment of sliding and rolling parts. So, too, it is well known that metallic particles are a principal root cause of lubricant aging and base oil oxidation.
With rare exception, ferrous particles caused by mechanical wear are also ferromagnetic, meaning these particles have inherent magnetic susceptibility. In some cases, this attribute is a drawback (e.g. the potential interference of solenoid actuators), but in most cases, it presents a distinct opportunity for efficient wear particle removal and detection.