Requirements for fixture materials: For general metal and nonmetal samples, the jaws of the fixture are in direct contact with the samples. Generally, high-quality alloy structural steel, alloy high-carbon steel (or low-carbon alloy steel) and cold-working die steel are selected, and their strength and wear resistance are improved through appropriate heat treatment processes (quenching and tempering, carburizing and quenching, etc.). ). Sometimes, special steel is embedded in the jaw or diamond sand is sprayed on the surface of the jaw. For some fixtures with small testing force, the surface in contact with the sample is made of sticky soft rubber. (For example, the clamping surfaces of plastic films, fiber yarns and other samples. ) The clamp is generally made of high-quality medium carbon steel and alloy structural steel, and its mechanical properties are improved by proper heat treatment process. Sometimes nonferrous metals such as aluminum alloys and special metals are used to reduce weight. Sometimes the requirements for casting structure (cast steel, cast aluminum, etc. For fixture structure: the design of fixture is mainly based on the test standards of materials and the types and materials of samples (especially finished products and semi-finished products). The above test standards refer to ISO, ASTM, DIN, GB, BS, JIS, etc. , as well as enterprise standards and industry standards. These standards generally have strict regulations on sample preparation and testing methods, and we can design different fixtures according to different samples and testing methods. Fixtures used for special samples (finished products and semi-finished products) are mainly designed according to the types and materials of the samples. The fixture itself has no fixed structure (for example, wires can be clamped by winding or two flat plates, metal sheet samples can be clamped by wedges, and metal sheet samples can be clamped by clamping), which is obviously different from the main machine. The main engine is similar at home and abroad, but the fixture is very different at home and abroad, and there are also great differences between different companies. This mainly depends on the overall level of the company and the experience accumulation of designers.