## Motor Sizing

Discuss AC Induction motors, Reversible motors, Synchronous motors, Low-Speed Synchronous motors, Torque motors, Gearheads, Brake Packs and related Accessories here.
jasonthoe
Posts: 6
Joined: Wed Dec 08, 2010 9:14 pm

### Motor Sizing

How do I determine the frictional coefficient of sliding surface? As shown in the technical reference, the frictional coefficient of sliding surface for standard ac motor an brushless DC motor is 0.3 while the frictional coefficient of sliding surface for low speed synchronous motor is 0.04. How about rollers that uses chain to move? Thanks for the help.

om_tech_support_JT
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### Re: Motor Sizing

The friction coefficients shown in the selection calculations are examples of various types of frictions that might be encountered in different systems. They are not related to the motors, but to the mechanical systems themselves. In the examples shown 0.3 was used to represent a higher frictional force for those systems. In the case of the third system with 0.04 as the friction coefficient this represents a "better designed" system with a very low friction. This may be due to different belt materials or surface finishes that resulted in a lower friction coefficient.

The key point is that the friction coefficients are not related to the motors. Friction coefficients range from ~1.1 to ~0.04 depending on the materials being used and the lubrication.

I hope you have found this information to be useful. Please let us know if you have any other questions. Thank you for your interest Oriental Motor.

jasonthoe
Posts: 6
Joined: Wed Dec 08, 2010 9:14 pm

### Re: Motor Sizing

Thanks for the help. Is there any table or list that you guys refer to for different type of material and lubricants used? I'm having a hard time figuring out what figure to used for different type of mechanism.

om_tech_support_JT
Posts: 1057
Joined: Fri Mar 12, 2010 2:59 pm
Location: Torrance, CA
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### Re: Motor Sizing

There are many resources online that lists coefficients of friction between different materials/surfaces. I would suggest doing an internet search for a quick answer (I've listed an example below). Besides the internet, many related mechanical engineering books will have some data on them as well.

Here's an example of what you can find on the internet:
http://www.engineeringtoolbox.com/frict ... d_778.html

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