Fourteen tolerance representations of the hottest

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There are 14 kinds of tolerances in mechanical drawing, including tolerance of late dimension and tolerance of form and position. They are also divided into shape tolerance, orientation tolerance, positioning tolerance and runout tolerance, which are respectively: straightness, flatness, roundness, cylindricity, line profile, surface profile, parallelism, verticality, inclination and position. Press the "print" key to print out all the detection contents, such as setting, coaxiality, symmetry, circular runout and total runout

parameters include not only geometric parameters in machining, but also parameters in physics, chemistry, electricity and other disciplines. So tolerance is a widely used concept. For mechanical manufacturing, the purpose of formulating tolerance is to determine the geometric parameters of products and make their variation within a certain range, so as to meet the requirements of exchange or fit. Introduction to pendulum installed on dynamometer

the tolerances of geometric parameters include dimensional tolerance, shape tolerance, position tolerance, etc

① dimensional tolerance. It refers to the variation of allowable size, which is equal to the absolute value of the algebraic difference between the maximum limit size and the minimum limit size

② shape tolerance. It refers to the total allowable variation of the shape of a single actual element, including 6 items: straightness, flatness, roundness, cylindricity, line profile and surface profile

③ positional tolerance. It refers to the total amount of change allowed by the position of the associated actual element to the benchmark, which limits the mutual position relationship between two or more points, lines and surfaces of the part, including 8 items: parallelism, verticality, inclination, coaxiality, symmetry, positional degree, circular runout and total runout

tolerance indicates the manufacturing accuracy requirements of parts and reflects the difficulty of processing

the tolerance grade is divided into 20 grades: IT01, it0, it1, it18. The grades are reduced in turn, and the tolerance value is increased in turn. It means international tolerance

the basic principle for the selection of tolerance grade or tolerance value is: the comprehensive economic effect of the manufacturing cost and use value of machine parts should be the best. The general matching size should be it5 ~ it13, the matching size of special precision parts should be it2 ~ it5, and the non matching size should be it12 ~ I. the material industry is the foundation of the whole industrial system T18, and the raw material matching should be itshapeways, which is the first full-color plastic 3D printing material 8 ~ IT14

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