Rotational Torque Required.....

[skh50]

I have a design where I am implementing a servo motor to unwind a threaded core from a molded piece of plastic. I need to calculate the amount of torque the servo motor will require.

I have the coefficient of friction of the plastic being used.

Is there a formula to calculate rotational torque for this application?

Thanks for the assistance.

 

[CoryPad]

There are formulae depending on the thread form. The generic subject is Power Screws, which is covered in textbooks like Shigley and Mischke.

 

[BobM3]

I'd think it would depend on how tight the cooling plastic grabs the threads on the core.