1, the clamping is reliable, can not slip.
2, if the clamp is convenient to use, safe
3, do in the test process, good sample breakpoints. Data with low dispersion. (i.e. samples continuously, jaw, jaw in parallel or standard length)
But there are several types of materials, with their characteristics and applicable environment is special, so far, the solution is not much
1, the finished products and semi-finished products and detection, require the fixture is all kinds of, how personalized to meet customer requirements, for all test machine manufacturers, is a challenge.
2, steel wire, steel strand due to high hardness, the internal structure is relatively loose, during the tensile test of uneven force, clamping jaw reason specimen easy wearing, fixture has not been well resolved. The past is the foil to do, a test will cost four pieces of foil, too much waste. Now using a tensile testing machine fixture spraying emery, slipping problem solved, but the position of fracture has not been ideal, 10 root samples only around half of success.
3, the large amount of deformation of the material due to large deformation, so the clamping difficult, fixture design is a difficulty.
4, for large batch, high frequency test, foreign commonly used automatic clamping, on domestic testing machine manufacturer, is still a new topic
5, for the test under high temperature do, fixture requirements are very high, both to high temperature, and no deformation, small size, so the test machine manufacturers in general, it is difficult to get things.