Things to Consider Before Buying Grips for Tensile Testing
Presto is the leading manufacturer and supplier of the tensile testing machine since three decades. With such a rich experience in the material testing industry, we understand the importance of right grip selection for perfect testing of samples. With the availability of ample of options, it sometimes becomes tricky to choose the perfect grip. In this post, we will highlight some points that would help in the selection of grips wisely.
Wrong grips selection not only brings the inaccurate test results but also the frustration of sample failing and wastage of energy. Before choosing the grip or fixture you must make sure what type of testing you are going to conduct plus what is the capacity. Overloading may result in the damage of grips. Common problems that are experienced are;
• Slippage of specimen
• Breakage of specimen from grip face
• Improper clamping due to improper shape
Slippage of Specimen
Sometimes due to the basic properties of the material, the sample tends to slip. While in major cases of slippage, the reason is improper grip selection. There many reasons for this. One of them is the shape of the grip that could not hold the sample properly. Most of the standards advise that at least 3/4th area of the sample is gripped by the jaw. Only then it can be declared as properly clamped.
Breakage of sample at the grip face
Sometimes, we try to play smart and choose grips that are meant for hard materials and try to use them universally for all types of grips. Since the grips are designed for hard metal they might result in overexertion of pressure on the samples like rubber on plastic samples. This results in breakage of the sample from the grip face. The force applied to fracture the sample is not actually measurement of breaking strength
of the material. If the sample breaks from anywhere but apart from the centre of the material it can be discarded. There are, of course, some margins regarding the fracture but breakage too close to the edges are discarded.
Awkward shape of the sample
While buying the grips, you must be very sure that whether you want to test the samples or the end products. However, there are no defined standards for the testing of end products. So, you have to be very careful while choosing your grips. Whether the chosen grip can accommodate your product or not.
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