Re: Co-efficient of friction problem
Hello Friends!!
1)Define Co-efficient of Friction in related to fasteners.
2)Factors affecting Coefficient of Friction
3)How is it determined?
4)How co-efficient of Friction affects parts failure in regards to ELV compliance?
1) The definition of coefficient of friction does not change for a fastener. Picture a threaded fastener as an inclined plane that has been wrapped around a cylinder. The flanks of the thread form the surface of this inclined plane. While the geometry is a little more complex than this (e.g., the surface is tilted), it essentially holds true.
2) lubrication, plating, type of plating, contamination, etc.
4) In threaded fasteners, there are two basic issues that could occur. If a threaded fastener is contaminated with oil the friction is reduced. This means that at a given torque, the fastener will turn more times than it would have under typical friction. This places a higher tensile load on the fastener that could lead to immediate tensile failure, or a longer term failure. Another situation is a threaded fastener with a heavy plated coating. This could increase the friction leading to fewer turns under the same torque, which in turn places a lower tensile force on the fastener. This may lead to failures from inadequate clamp forces or long term loosening of the fastener.