Radial Force on Ball Bearing Via Vice Setup, Type of Vice Recommendation Needed

Rivers · Oct 29, 2020

I'm building a test rig to test the life of ball bearings by applying dynamic radial force on them.

I have decided to use a vice and modifying the jaws so they exert opposing forces on two different bearings.

I have poor knowledge on types of vices and would like some help selecting a proper vice for my application.
The vice must be able to exert a ton (2,000 lbs) of force (or is the correct term pressure?) and must be able to hold that constant force for an extended period of time (up to a week if possible).

The bearings being tested have an outer diameter of around 1.5 to 2 inches. What are your recommendations?

Thank you,
Jake

crrmeyer · Oct 31, 2020

Rivers said:
I'm building a test rig to test the life of ball bearings by applying dynamic radial force on them.

I have decided to use a vice and modifying the jaws so they exert opposing forces on two different bearings.

I have poor knowledge on types of vices and would like some help selecting a proper vice for my application.
The vice must be able to exert a ton (2,000 lbs) of force (or is the correct term pressure?) and must be able to hold that constant force for an extended period of time (up to a week if possible).

The bearings being tested have an outer diameter of around 1.5 to 2 inches. What are your recommendations?

Thank you,
Jake

Consider a pneumatic vise.

Example:
Heinrich Company - Air Vises with Single-Acting Cylinders - Racine, Wisconsin

Easy to get the force you want. Should not drift over time if used with a constant pressure source or regulator.

crossthread · Oct 31, 2020

If you need to go low budget then may I suggest an arbor press and a strain gauge.

310 Guy · Oct 31, 2020

Rivers said:
I'm building a test rig to test the life of ball bearings by applying dynamic radial force on them... What are your recommendations?

I recommend that you look at the bearing manufacturer's engineering manuals. Timken and SKF both have extensive manuals online. All of the testing has already been done and the info is in the manuals.
Bill

Rivers · Nov 2, 2020

Thanks for the suggestion, This is simply for teaching purposes for a Tribology course and to examine the wear on the bearings.

magneticanomaly · Nov 2, 2020

I guess you know that the normal failure mode for properly applied rolling-element bearings is not "wear" per se, but subsurface fatigue leading to spalling?

dian · Nov 2, 2020

not sure how a vise will apply dynamic forces.

Rivers · Nov 2, 2020

magneticanomaly said:
I guess you know that the normal failure mode for properly applied rolling-element bearings is not "wear" per se, but subsurface fatigue leading to spalling?

Correct, I am interested in spalling, brinelling and fretting. Pretty much any failure mode.

Rivers · Nov 2, 2020

dian said:
not sure how a vise will apply dynamic forces.

The force would be constant, but the Inner race of the bearing would be spinning via a shaft.

A vice with a simple jaw modification would apply force to the two bearing on the shaft from opposing sides.

Rivers · Nov 2, 2020

crrmeyer said:
Consider a pneumatic vise.

Example:
Heinrich Company - Air Vises with Single-Acting Cylinders - Racine, Wisconsin

Easy to get the force you want. Should not drift over time if used with a constant pressure source or regulator.

Thank you, will look into this.
Would you say a drill press vice is not able to hold similar forces over time?

Halcohead · Nov 2, 2020

Rivers said:
I'm building a test rig to test the life of ball bearings by applying dynamic radial force on them.

I have decided to use a vice and modifying the jaws so they exert opposing forces on two different bearings.

I have poor knowledge on types of vices and would like some help selecting a proper vice for my application.
The vice must be able to exert a ton (2,000 lbs) of force (or is the correct term pressure?) and must be able to hold that constant force for an extended period of time (up to a week if possible).

The bearings being tested have an outer diameter of around 1.5 to 2 inches. What are your recommendations?

Thank you,
Jake

A vise is a poor choice for this application because vises are designed to have high stiffness, which means the force applied to the bearings will change a lot for minor changes in the center distances of the bearings (eg due to dust/dirt between them or even asynchronous runout in the bearings). This will mean the bearings will feel “crunchy” or “lumpy” as you turn them under load, and the load will vary a lot as they turn.

If you use a vise you will need a flexible element supporting one bearing to reduce the overall stiffness. You will likely benefit from the help of a local mechanical engineer to review or guide your design.

2000 lbf is not a lot of force for a vise, but there are other relevant factors beyond the force.

Rivers · Nov 2, 2020

You bring up good points, I will do more research into the matter. As you suggest, a flexible element is probably the way to go in order to reduce big loading changes. I had also considered a simple lever system to place the load on the bearing, but reaching high forces was impractical even with a good mechanical advantage.

CalG · Nov 2, 2020

An arbor press with a sliding weight on the lever arm would be just the ticket.

Sized to suit the required pressure, they even come job rated "by the ton".

Of course, you would need a bench to place it on.

Rivers · Nov 2, 2020

I like this idea, my only concern is the bending stress on the shaft and the toll on the motor And other components (pillow block bearings or saddle bearings for support).
Initially, I wanted to test one bearing but decided to put equal loads unto two bearing in order to resolve the loaded shaft problem. This is why I gravitated to a vice similar to a drill press. Two opposing forces on the two bearings will leave the shaft close to unloaded, if that makes sense.

dian · Nov 3, 2020

can you draw a picture of what you are doing? shaft parallel to jaws and vice somehow assmetrically squeezing the bearings? dont you want to have some controll over the force? fine adjustment, measurement? a vice is not suitable for this.

i would use a leveraged fish scale for this purpose.

crrmeyer · Nov 3, 2020

Rivers said:
Thank you, will look into this.
Would you say a drill press vice is not able to hold similar forces over time?

Yes, that is the issue. You also need a transducer to calibrate the force. With the pneumatic vise the force is calculated using F = P * A where the A = the area of the pneumatic cylinder. Heinrich pneumatic vises can be had for cheaper on Ebay if used is OK.

Mr Bridgeport · Nov 3, 2020

As was stated earlier, an arbor press with a weight on the arm will allow you to set the exact amount of force. If the bearing heats up and expands a tiny fractional amount it will keep the force the same. Motor drive from underneath would be easy to add.

Mr Bridgeport

CarbideBob · Nov 3, 2020

I do not understand what is going on here.
Vice or press, very different.
Bob

Mr Bridgeport · Nov 3, 2020

CarbideBob, If I'm not mistaken he wants to load a ball bearing to the point of failure in a laboratory setting. He needs to exert 1000 lbs of force axially on the inner bearing race while it's spinning.

An arbor press would be easy to calibrate, place a bathroom scale under the arbor with the handle perpendicular to the ground and hang a weight off the end of the handle. With a little math you can calculate the exact weight needed to get to 1000 lbs of force. Thermal growth considerations as the bearing gets hot can be ignored, in a vise the preload will skyrocket.

BillWojo

CalG · Nov 8, 2020

Rivers said:
I like this idea, my only concern is the bending stress on the shaft and the toll on the motor And other components (pillow block bearings or saddle bearings for support).
Initially, I wanted to test one bearing but decided to put equal loads unto two bearing in order to resolve the loaded shaft problem. This is why I gravitated to a vice similar to a drill press. Two opposing forces on the two bearings will leave the shaft close to unloaded, if that makes sense.

If shared loads is your issue, You are hunting the wrong game. loads are NEVER shared predictably.

Radial Force on Ball Bearing Via Vice Setup, Type of Vice Recommendation Needed

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