Q: I have a 1 kN load cell. How do I determine if a specimen would be too heavy for my tensile and compression tests?
A: To be cautious, always use mechanical limits to ensure that grips or platens aren’t compressed onto each other. The specimen weight is not often an issue, but if you're using our load cells, they incorporate several overload prevention features. When combined, the weight of the upper grip and the expected maximum load during testing should be less than one-and-a-half times the load cell capacity. In this case, 1.5 kN.
A: To be cautious, always use mechanical limits to ensure that grips or platens aren’t compressed onto each other. The specimen weight is not often an issue, but if you're using our load cells, they incorporate several overload prevention features. When combined, the weight of the upper grip and the expected maximum load during testing should be less than one-and-a-half times the load cell capacity. In this case, 1.5 kN.
5 comments:
What happens to the accracy of the load cell above 100%?
Thanks for the question. Your question can be interpreted several ways, and not knowing the specific concern you have, I’d appreciate the chance to talk with you. Please feel free to email me at your convenience: EMBlogSupport@instron.com.
The nonspecific answer is that the accuracy should not be affected very much, if at all, however verifications or calibrations are not performed above 100% capacity. Our latest generation load cells can withstand up to 300% of the rated capacity without mechanical damage and up to 150% without zero shift.
The graph at the end of this document (http://www.instron.us/wa/library/streamfile2.aspx?sdoc=1223) is a depiction of how linear the accuracy is over the measuring range.
Further comment on the original question - a typical 1 kN capacity grip or compression platen can weigh anything from a few hundred grams to a few kilograms. This is small compared to the capacity of the load cell.
The weight of the grip/platen becomes more significant in very low force applications.
Instron systems are designed to stop the machine at 100% load cell capacity to prevent damaging the load cell and system.
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