Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/190260
LESSONS IN LUBRICATION particles produce irregular shapes. During surface adhesion, the asperities of two contacting surfaces flatten each other, creating a fracture on one of the surfaces. The surface interaction transfers fragment material, which adheres to the opposing surface. This can result in the formation of particles that have unusual shapes and are a mixture of elements. The shapes often are difficult to define, as several wear modes may be at work concurrently within the system. As these wear particles act as abrasive contaminants between continually contacting surfaces, they transform into unusual shapes. Non-Ferrous Corrosion Particles Corrosion particles typically are extremely small (submicron). Magnetic collection techniques can be effective in gathering these particles, which are too small to view in individual detail. Ferrous Oxide Particles Oxide particles, which are either red or black iron oxides, are produced from chemical reactions between iron and oxygen. Red oxides are an indication of moisture in the system, while black oxides indicate inadequate lubrication and excessive heat generation in the system. Other Particles The particles described previously comprise only those generated from wear-induced causes, but a mechanical system can contain an assortment of other particles from environmental contaminants like water, dust, etc., to human-agency contaminants such as machining byproducts. Even some lubricant additives can be mistaken for wear particles during wear debris analysis. Nevertheless, wear debris analysis is quite useful for discovering which degrading actions are occurring within a machine or how a machine failed. Although analysis techniques such as observations from precise heat treatments or adding specific chemicals can help in determining the elemental composition of particles, spectrometric analysis is generally more effective in providing the elemental This illustration shows how the various types of wear particles are associated with the different wear modes. 44 | September - October 2013 | www.machinerylubrication.com