Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1470959
www.machinerylubrication.com | May - June 2022 | 33 ML ML ML ML Built in When a machine comes in new from the OEM or has been brought back to the plant after a rebuild, it is always a good idea to perform a flush. This flush will help send any particles that may still be in the machine out the drain port. Ingested Particles can be ingested from the process, atmosphere or combustion by way of leaking seals, pipes and hoses; the most common method of entry is through the headspace. Open hatches or ports on the top of a reservoir should be closed to deter particle entry. One of the most overlooked items for particle ingression is the breather. Machines often come with a vent or vented plug to allow a machine to breathe. These allow a direct path for contaminants. Hydraulic lubricants often have tight cleanliness goals but think of the headspace protec- tion on most of the units — a cap with tightly woven steel wool. Replacing these with a low micron filter will help eliminate this easy path. Generated Particles coming from this type of ingression are most often controlled by lubricant filters. Something to consider here, though: remember the size of the film thicknesses we discussed earlier? If your components are separated by very small film thicknesses, and you are running a 40 micron filter, are you eliminating the particles that are doing the damage? When choosing filters for machines, it is important to keep your lubricant cleanliness goals in mind. • Hydrodynamic Lubrication (Sliding) — Typical oil films are 5-20 microns. • Elastohydrodynamic Lubrication (Rolling) — Oil films can be less than 1 micron. Breaking it Down Another issue with small particles is that they are harder to break down. To understand this concept better, think of breaking a large stick down to use for kindling in your fire- place. When the stick is long, you can snap it over your knee or in your hands, breaking the larger stick into smaller pieces; however, if you have done this before, you know that when you get a stick about the size of your hand, it's almost impossible to break down any further. e same is true of small particles; instead of being broken down to even smaller sizes when they pass through the load zone, they cause abrasive wear.