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Monday, 4 May 2015

Material used for Belts

Material used for Belts Points : material used for belts, cotton or fabric belts, balata belts, leather belts, rubber belt Material uses for belts and ropes have to be strong, flexible, and tough. It should have a high coefficient of friction. Belts, according to material use, are classified as follows: 1. Cotton or fabric belts Mainly of fabric belts are prepared by folding convass or cotton duck to three or more layers (depending upon thickness preferred) and stitching jointly. These belts are woven also into a strip of preferred width and thickness. They are impregnate by some filler similar to linseed oil in order to make belt water-proof and to stop injury to fibres. The cotton belts are cheaper and proper in warm climate, in damp atmosphere and in expose positions. As the cotton belts necessitate little attention, thus these belts are generally use in farm machinery, belt conveyor and so on. 2. Balata belts These belts are like to rubber belts excepting that balata gum are use in place of rubber. These belts are acid resistant and water proof and it is not effect by animal oils or alkalies. Balata belts must not be at temperatures over 40°C because at this temperature the balata begin to soften and become sticky. Strength of balata belts is 25 percent greater than rubber belts. 3. Leather belts The mainly significant material for flat belt is leather. The finest leather belts are prepared as of 1.2 metres to 1.5 metres long strips cut as of either side of back bone of top grade steer hides. Hair side of leather is smoother and harder than flesh side, but flesh side is stronger. Fibres on hair side are at right angles to surface, as those on flesh side are interweave and parallel to surface. Thus for these reasons hair side of a belt should be in contact by pulley surface. This gives a extra close contact among belt and pulley and places most tensile strength of belt section on outside, where tension is highest as belt passes over pulley.

Leather can be also oak-tanned or mineral salt-tanned e.g. chrome-tanned. In order to raise the width of belt, strips are smooth mutually. Belts are particular according to number of layers e.g. single, double or triple ply and according to thickness of hides use e.g. light, medium or heavy. Leather belts have to be occasionally clean and decent or treated by a compound or dressing contain neat foot or other proper oils so that belt will continue soft and flexible.
4. Rubber belt Rubber belts are prepared of layers of fabric impregnate by rubber composition and have a thin layer of rubber on faces. These belts are extremely flexible but are rapidly destroyed if acceptable to come into contact by heat, oil or grease. One of principle benefit of these belts is that they can be simply made endless. These belts are initiate proper for saw mills, paper mills where they are exposing to humidity.

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