×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Hydraulic grips clamping force

Hydraulic grips clamping force

Hydraulic grips clamping force

(OP)
Hello there,
I've got a problem regarding the clamping force on hydraulic grips on a universal testing machine.
For aluminium alloys works fine, but when i try on steel, it fails maintaining the clamping force on the grips.
The question: are there specifications regarding clamping forces for specimens?
Thank you in advance, and excuse the bad english.

RE: Hydraulic grips clamping force

Please post about how it is failing, like the sample is slipping out of the jaws.  A picture of the holder would be a great help.
Also check the limits on sample size.

Get the manual for your testing machine and checkout it's capabilities as some are not intended for Steel. We have machines that are only good for polymers, composites, etc. A lot of machines that are capable of testing different materials require one to change the jaws are grips for different materials.  

RE: Hydraulic grips clamping force

Yes, sounds like it is not set to squeeze the aluminum very hard, then when you put the steel sample in, because it weighs so much more, it slips out.  (guessing without more information)

RE: Hydraulic grips clamping force

(OP)
Back with more info:
The machine it's a hydraulic 300kN testing machine.
All sample can and are fixed within grips, but, after test
is started, at different load(10-15kN) values, for steel samples
the test stops, claiming that a break was detected.
The sample did not break.
Bellow are some pictures with the grips and the sample.
The sample is deformed after retrieval.

RE: Hydraulic grips clamping force

please load it up as a pdf and not a rar file

RE: Hydraulic grips clamping force

If your sample slips in your machine then it  will sense a break due to changing load.   If the grip is holding then you have a problem in the machine recording mechanism.  Check the setting on the limit switch, whether it is loose, check and it for proper operation.  On most machines there is peak picker that recods the highest value obtained.   On some machines this is incoperated with the limit system.  

Are the jaw teth sharp and clean>

Are the jaws harder than your steel sample?

Does this happean at the same load each time?

RE: Hydraulic grips clamping force

(OP)
The cause was a faulty electrovalve in the gripping mechanism,
at least so it seems.
Thank you all for the sugestions.

RE: Hydraulic grips clamping force

Appreciated the feed back.

Hope you have it under control.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources