How to check applied force?

[var10]

Hi

We have these series 4 pemserter on which I can set the force to a required value and install clinch nuts on to aluminium parts. But I would like to know what is the applied force on the part during pressing as sometimes there may be leaks in the pneumatics/pressure loss etc. Should I use a load cell to get an accurate force interpretation or can I just go with whatever the dial states.

Thanks,

V.

 

[var10]

Any help from someone who has used this pemserter will be appreciated.

 

[3DDave]

According to the user manual, it takes up to 100 psi, so if it's getting that much, then it should work right. The force is regulated by a pressure regulator, so if you don't believe what you are getting, taking the pressure downstream of the regulator should provide that. You'd need to look at the leverage to go from pressure and cylinder area to get force exerted.

http://www.pemnet.com/presses/pdf/ps4/English.pdf

also has contact information for factory help.

 

[MikeHalloran]

Are you having product quality issues, or is this just idle curiosity speaking?

Personally, if the company has the budget for it right now, I'd buy a load cell, sized to deal with the pemserter and whatever other stuff might present force questions down the road, when maybe the cash won't be there.

Actually, a load cell and display should probably be in regular use by your QA department, should you someday have one of those.



Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

I would use a load cell to periodically calibrate the dial.

 

[KENAT]

I was thinking similar Mint - maybe even do it at the start of each shift or similar if you're that concerned about variability.

Posting guidelines faq731-376

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

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[var10]

Thanks guys.Yes I have had problems in the past, as we approach production stages we want consistency in our products. So would like to know what force reaches the metal. Calibrating at the start of each shift sound like a good idea.

 

[3DDave]

Unless the machine is broken or the plant isn't supplying the required air pressure, material hardness will have a larger effect on consistency.

 

[var10]

Dave - You are right, sometimes we do have situations when the pressure isn't quite right due to a whole lot of other things. I think I might go with Low profile compression load cell to suit our requirements. The problem now I face is how to mount it in between the punch and anvil and how to hold it there onwards. Considering making a Jig to mount and hold it in place.

 

[var10]

If the punch strikes the load cell will it cause damage to the load cell? Is it better to use a load bearing plate?

 

[3DDave]

If your pressure supply is not dependable, then using a load cell is not dependable because the conditions measured by the load cell are not repeatable. The first order of business is to verify the air pressure supply is at least what is needed to operate the machine, and if you are worried about the reglator in the machine, add a pressure sensor in the cylinder part of the circuit.

Otherwise it's like calibrating a speedometer when it's known the needle sticks.

 

[var10]

It is more like checking the force just before we do the production run. Once the machine is fired up, we usually don't have problems. But I do see you have a valid point.