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Selecting the best material for gears?

  1. Jan 2, 2016 #1
    This system consists of a shaft that is connected to a motor that is rotating at 200rpm. The whole shaft consists of two gears.

    The input power of the system is 500W. Is there a way i can calculate how exactly i can find the best material for my gears that is able to withstand the input power of the system of 500W?

    If there is any other method i would like to know. Thanks!!
  2. jcsd
  3. Jan 2, 2016 #2


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    I'm not an expert but....

    You can calculate the torque from the power and angular velocity (rpm). Torque is the rotational equivalent of force so its a measure of the stress acting on the gear teeth. There should be a way to relate that stress and the size of the teeth and calculate the strength of the material required. Not something I've done unfortunately.

    Other factors also influence the choice of materials such as wear and maintenance. For example some plastics are self lubricating.
  4. Jan 2, 2016 #3
    There are many different materials used in making gears. I have cut many gears from 10’’-220’’. Most gears of that size use a hob cutter. Depending on friction and speed you may need to have a lubrication method. There are many teeth shapes you may not have thought about. (Helical, straight, worm Engineersedge.com) For lighter gears Nylon, PVC, Canvas, and Kevlar maybe strong enough. The normal heavier gears are Brass, 303-408 stainless steel, and carbon steel.

    From wiki

    Hp=Tx n/63000 → T = Hp x 63000/n

    T = Rm x Wt → Wt = Hp x 63000/ n x Rm

    Axel position is very important, too close you burn or smash your teeth, too far out you skip or destroy your gears. Mechanics call it teeth back-lash, gears are a science of their own. A very lucrative engineering field where CAD cannot always find the answer. Sometimes Belts and chains are easier.
  5. Jan 8, 2016 #4


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