Basics of drilling 5
- 1. BASICS OF DRILLING-5 I. Satyanarayana, M.Tech,MBA,MCA Dy. Manager, Project Planning, SCCL, isnindian@gmail.com, visit at www.slideshare.net/isnindian ISN
- 2. BIT WEAR MECHANISM The four most significant wear processes are 1. Adhesive wear, 2. Abrasive wear, 3. Corrosive wear, and 4. surface fatigue wear. ISN
- 3. Adhesive Wear • When two surfaces are brought together, an attraction force is set up between the atoms on the surfaces of the two bodies. • If the bodies then are separated, this attractive force attempts to pull material from one surface onto the other. • Any material removed in this way is termed an adhesive wear fragment. • Although this is the most common of all wear mechanisms, it is not the most important mechanism for rock cutting tools. ISN
- 4. Abrasive Wear • This form of wear occurs either when a hard, rough surface slides against and plows grooves in a softer surface, or when abrasive particles are introduced between two surfaces and these particles abrade material from one or both surfaces. • This is the most common and the most important wear mechanism for rock cutting tools. In this case, the rock debris formed by the tool constitutes the wear particles that abrade the tool. ISN
- 5. Corrosive Wear: This form of wear occurs when sliding takes place in a corrosive environment. This mechanism is not of great concern for rock cutting bits. Surface Fatigue Wear: Repeated mechanical or thermal loading cycles can lead to the formation of fatigue cracks in the surface or subsurface of a material. These cracks eventually cause breakup of the surface with the formation of large fragments. ISN
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