Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1336798
2 | January - February 2021 | www . machinerylubrication.com By Gerardo Trujillo & Jim Fitch Condition M onitoring , Lubric ant Analysis and Trouble shooting " AS I SEE IT Jim Fitch | Noria Corporation Dust Cakes: What Causes Them and Why You Should Care We've all seen them. Perhaps some of us da ily. Ma ny ta ke on a certain beauty, almost like a natural cave forma- tion or a work of art. Most have organic characteristics like mosses or algae. Dust cakes need airborne dust and oil to feed their growth. Some get their oil from escaping headspace mist, while others extract oil themselves from adjacent grease by a slow, sucking action (capillary forces) within the cake. Leaking oil from machine case joints and seams can lead to enveloping dust cakes too. e available supply of oil and dust determines the growth rate and the wrath they can impart. No one enjoys removing and cleaning this muck, which is often why dust cakes continue to grow. We see them but we don't see them, like a dirty smudge on a carpet. After a while, they get subconsciously blocked from our view and concern. Of course, such blindness feeds a lethargic and dismissive culture that is contrary to any serious reliability effort. A good place to start to turn things around is to understand the real danger of doing nothing or No one enjoys removing and cleaning this muck, which is often why dust cakes continue to grow. " Figure 1. Backstop breather has caked-on dirt down the elbow and along the case. This is usually due to oil mist that has migrated out of the headspace and collected on nearby surfaces. Airborne particles adhere and build up on the oil-damp surface forming layers of heavy, caky grime. Too much oil mist results in the need for frequent top-ups (oil and labor costs) and fluctuating oil level control. In many cases breathers function much better and last longer if they are positioned higher with a pipe extension. Ref. Kevin Albert Figure 2. Notice how far oil from purged grease travels along the base and case wall. Figure 3. Dust cake buildup near leak area on gear case and base. Notice sight glass and oil fill port. Ref. Torki Ibrahim Factor: A7M