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Load Inertia  Mass Moment of Inertia Question 
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#1
Nov1208, 10:17 AM

P: 9

I'm looking for some help to verify a calcualtion that was made by a previous employee.
The calcualtion was for load inetria (reflected to the motor). The motor will be driving (3) rollers at a gear ratio of 3.5:1 (motor turns 3.5 revolutions for every 1 revolution of the rolls). I have a program that caluclates the mass moment of inertia for the rolls, and was able to verify this calucations with formulas that I found on the internet. The total inertia for all (3) rolls is 67,155 lbmin^2. I converted this to 19.65 kgm^2. If I divide this by the gear ratio of 3.5, I come up with 5.6 kgm^2. The previous employee came up with 2.4 kgm^2. Can someone help to tell me what I'm doing wrong. Thanks, I 


#2
Nov1708, 11:31 AM

P: 2

Take a look below to see if any of these equations are useful. The reflected inertia is the (load inertia) / (gearing ratio^2).
I came up with 1.604 kgm^2. Let me know if you want me to run it through my simulator. Note: I didn't include the gearing inertia  should be minor if you're using a belt system. http://www.danahermotion.com/website...ggearheads.pdf 


#3
Nov1708, 01:01 PM

P: 9

I'm assuming the 50% saftey factor. Thanks much your all the help.



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