Load Inertia - Mass Moment of Inertia Question

In summary, the conversation is about verifying a calculation for load inertia reflected to the motor. The motor will be driving 3 rollers at a gear ratio of 3.5:1. The total inertia for all 3 rolls is 67,155 lbm-in^2 or 19.65 kg-m^2. When divided by the gear ratio, it should result in 5.6 kg-m^2. However, the previous employee's calculation was 2.4 kg-m^2. The individual is seeking help to determine the error. The conversation also mentions a program that calculates the mass moment of inertia for the rolls and provides a link to equations that could be useful. The individual has also calculated a reflected inertia of
  • #1
mselak500
9
0
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 lbm-in^2. I converted this to 19.65 kg-m^2. If I divide this by the gear ratio of 3.5, I come up with 5.6 kg-m^2.

The previous employee came up with 2.4 kg-m^2.

Can someone help to tell me what I'm doing wrong.

Thanks,

I
 
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  • #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 kg-m^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/com/eng/download/document/sizinggearheads.pdf [Broken]
 
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  • #3
I'm assuming the 50% saftey factor. Thanks much your all the help.
 

1. What is load inertia?

Load inertia refers to the resistance of an object to changes in its rotational motion. It is typically measured in terms of mass moment of inertia, and it reflects the distribution of mass around the axis of rotation.

2. How is load inertia calculated?

Load inertia is calculated by multiplying the mass of the rotating object by the square of its distance from the axis of rotation. This value is then summed for each individual component of the system to determine the total load inertia.

3. Why is load inertia important?

Load inertia is important because it affects the performance and stability of rotating systems. A high load inertia can result in slower acceleration, increased power requirements, and potential instability in the system.

4. How does load inertia impact the design of a system?

The load inertia of a system must be taken into consideration during the design process to ensure that the motor or drive system is capable of providing enough torque and power to overcome the inertia and achieve the desired performance. In some cases, additional components may be necessary to reduce or manage the load inertia.

5. Can load inertia be changed?

Yes, load inertia can be changed by altering the mass and/or distribution of mass in the rotating system. This can be achieved by adding or removing components, changing the shape or size of existing components, or using materials with different densities.

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