1 .Mold processing quality includes processing accuracy and surface quality
Machining accuracy is the degree of conformity of the three geometric parameters of the actual size, shape and position of the surface of the processed parts with the ideal geometric parameters required by the drawings. The ideal geometric parameter is the average size for the size; for the surface geometry, it is absolute circle, cylinder, plane, cone and straight line; for the mutual position between the surfaces, it is absolute parallel , Vertical, coaxial, symmetrical, etc. The deviation between the actual geometric parameters of the part and the ideal geometric parameters is called machining error.
Both machining accuracy and machining error are terms for evaluating the geometric parameters of the machining surface. The machining accuracy is measured by the tolerance level. The smaller the grade value, the higher the accuracy; the machining error is expressed by a numerical value. The larger the value, the greater the error. High processing accuracy means small processing error and vice versa.
The actual parameters obtained by any processing method will not be absolutely accurate. From the function of the part, as long as the processing error is within the tolerance range required by the part drawing, it is considered that the processing accuracy is guaranteed.
The quality of the machine depends on the machining quality of the parts and the assembly quality of the machine. The machining quality of the parts includes the machining accuracy and surface quality of the parts. The machining accuracy refers to the actual geometric parameters (size, shape and position) and ideal geometry of the parts after machining. The degree to which the parameters match. The difference between them is called machining error. The size of the processing error reflects the level of processing accuracy. The larger the error, the lower the processing accuracy, and the smaller the error, the higher the processing accuracy.
2 The main aspects that affect the processing accuracy
2.1 Dimensional accuracy
Refers to the degree of conformity between the actual size of the processed part and the tolerance zone center of the part size.
Dimensional accuracy is controlled by dimensional tolerances. Dimensional tolerance is the allowable variation of part size during cutting. In the case of the same basic size, the smaller the dimensional tolerance and the higher the dimensional accuracy.
2.2 Shape accuracy
Refers to the degree of conformity between the actual geometry of the surface of the processed part and the ideal geometry. There are 6 items to evaluate the shape accuracy, such as straightness, flatness, roundness, cylindricity and line contour. The shape accuracy is controlled by the shape tolerance. Except for the roundness and cylindricity, each shape tolerance is divided into 13 precision grades, and the rest are divided into 12 precision grades. Level 1 is the highest and level 12 is the lowest.
2.3 Position accuracy
Refers to the difference in actual position accuracy between the relevant surfaces of the parts after machining. There are eight items for evaluating position accuracy: parallelism, perpendicularity, inclination, coaxiality, symmetry, position, circular runout and full runout. Position accuracy is controlled by position tolerance, and the position tolerance of each item is also divided into 12 accuracy levels.
3 The relationship between dimensional accuracy, shape accuracy and position accuracy
Usually when designing machine parts and specifying the machining accuracy of parts, care should be taken to control the shape error within the position tolerance, and the position error should be less than the dimensional tolerance. That is, precision parts or important surfaces of parts, the shape accuracy requirements should be higher than the position accuracy requirements, and the position accuracy requirements should be higher than the dimensional accuracy requirements.