Ball Screw Lead Value Selection Rules of Thumb 1

[Helepolis]

Hi all,

This might seem trivial to some but I was wondering if there are some guide rules on selecting the correct lead value on a ball screw.

So far I've worked with closed linear systems (motor and linear guide in enclosed single unit), and now trying to design an "open" system to suit my requirements with a separate motor, ball screw and linear bearing to be assemble in my device.

This time google was useless for me.


Thanks,
SD

 

[MintJulep]

Define what you have and what you need for the following. Select the lead that gets you there.

Power (as Torque and Speed)
Precision
Resolution
Accuracy

 

[Helepolis]

My question wasn't what to define, but how to combine those things to get (select) the correct/suitable lead value.

 

[hendersdc]

If you have all the input parameters like the ones Mint mentions already defined there are a number of free ball screw calculators online, just google that term and find one that fits your needs.

 

[moon161]

"My question wasn't what to define, but how to combine those things to get (select) the correct/suitable lead value."

This is a general component specification question. I'll insert a couple ball screw words so it's more specific.

1. Pick a couple dominant factors of your design, like load, life cycle and length of travel.

2. Contact a manufacturer's rep or sales engineer or website or catalog for a vendor, ask for a proposal/find an option based on your dominant factors.

3. Evaluate the proposal WRT all your design factors.

4. Repeat, possibly making adjustments on your requirements or seeking other vendors.

 

[Helepolis]

2. Contact a manufacturer's rep or sales engineer or website or catalog for a vendor, ask for a proposal/find an option based on your dominant factors.

The thing is that I would like to know/learn (at least the basics) how those factors are combined for targeting the correct solution.

Besides that, unfortunately because of where I live some of the manufacturers refuse to supply or even help altogether (for example I tried Hiwin, among others, and was politely refused).
Local suppliers/retailers are mostly lacking any service orientation and dealing with them is time consuming and counter productive.

 

[GregLocock]

One big deal for my application is the reverse drive efficiency. That is how much of the axial force gets turned back into torque. Something else to think about.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[handleman]

Generally, you want the required top speed of your mechanism to match the rated speed of your servo. The lead of the ballscrew is one of the pieces (along with gearbox) that you can select to achieve that.
However, you have to look out for the top allowable speed of the ball screw as well. There's a limit based on the speed of the balls.... Larger diameter screw with same lead means the balls travel faster. The other limiter is the dangerous speed of the screw shaft. This is based on the diameter and length. Basically, it's the speed at which any deformation from straight becomes an eccentric mass that centrifugal force causes to deform even further into a jump-rope.

Misumi has some good guidance on selecting ball screws. Begins here:

https://us.misumi-ec.com/maker/misumi/mech/product/bs/choice/