Selecting the best material for gears?

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Discussion Overview

The discussion revolves around selecting the best material for gears in a system driven by a motor operating at 200rpm with an input power of 500W. Participants explore methods for calculating material strength and consider various factors influencing material choice, including stress, lubrication, and gear design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about calculating the best material for gears that can withstand 500W of input power.
  • Another suggests calculating torque from power and rpm, noting that torque relates to the stress on gear teeth and implies a need to consider material strength.
  • Factors such as wear, maintenance, and lubrication methods are mentioned as influencing material choice, with some plastics being noted for their self-lubricating properties.
  • A participant shares experiences with various gear materials, mentioning that lighter gears may use Nylon, PVC, Canvas, and Kevlar, while heavier gears typically use Brass, stainless steel, and carbon steel.
  • There is a reference to the importance of gear tooth shape and axle position, highlighting the complexity of gear mechanics.
  • A link to additional resources on gear tooth strength is provided for further exploration.

Areas of Agreement / Disagreement

Participants express various viewpoints on material selection and calculation methods, indicating that multiple competing views remain without a clear consensus on the best approach or material.

Contextual Notes

Participants mention several assumptions regarding torque calculations and material properties, but these are not fully resolved within the discussion. The influence of lubrication and gear design on material choice is also noted but not exhaustively detailed.

Who May Find This Useful

This discussion may be useful for engineers, designers, or students interested in gear design, material science, and mechanical engineering principles.

Isaac_DB19
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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!
 
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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.
 
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 RmAxel 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.
 
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