Motor sizing query for design project.

[ukmitch86]

Hi there - this is my first post and I hope one of many to come!

My query is a relatively simple one; I'm working with an engineering cleaning application where fluid will be fed into a cylindrical block and spun out into a surrounding container.

The block is 3.5m long and ∅0.140m, weighing in at 92kg. It sits inside a vacuum chamber weighing 48.6kg, total 140.6kg.

I think a belt drive solution will be most practical from a design perspective, and I'm trying to size the motor to drive the load at a frequency of minimum 500RPM.

It's a long time since I've done this sort of calculation.

 

[anorlunda]

I would first and foremost look at the power requirement. How many watts of power do you need? For that you need:

1. The friction losses at maximum speed. Usually, that can not be calculated, but only determined by experiment.
2. The acceleration requirements. How much time is allowed to go from zero to full speed. That can be paired with the masses and moments of inertia of rotating pieces, and apply F=ma.

If those calculations prove difficult, the most common practical solution is to oversize the motor. The additional cost of a motor that may be 3-10 x bigger than your needs, may be cheaper that the cost of your engineering labor to calculate the minimum size.