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
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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.
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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.
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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.
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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.
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