What are the main reasons that affect the machining accuracy of molds?
- What are the main reasons that affect the machining accuracy of molds?
1. Dimensional accuracy
It refers to the consistency between the actual size of the processed part and the center of the part’s dimensional tolerance zone. Dimensional accuracy is controlled by dimensional tolerances. Dimensional tolerance is the allowable variation in part size during cutting. When the basic dimensions are the same, the smaller the dimensional tolerance, the higher the dimensional accuracy.
2. Shape accuracy
Refers to the consistency of the actual geometry and ideal geometry of the surface of the part after machining. Items for evaluating shape accuracy include 6 items such as straightness, flatness, roundness, cylindricity, and line profile. Shape accuracy is controlled by shape tolerance. Except for the 13 precision grades of roundness and cylindricity, each shape tolerance is divided into 12 precision grades, and the rest are divided into 12 precision grades. Level 1 is higher, level 12 is lower.
3. Position accuracy
Refers to the actual position accuracy difference of the relevant surface of the part after machining. Items for evaluating position accuracy include parallelism, perpendicularity, inclination, coaxiality, symmetry, positional degree, circular runout, and full runout. Position accuracy is controlled by position tolerance, which is also divided into 12 accuracy levels for each item.
4. Relationship between dimensional accuracy, shape accuracy and position accuracy
Usually, when designing mechanical parts and specifying the machining accuracy of the parts, attention should be paid to controlling the shape error within the position tolerance, and the position error should be smaller than the dimensional tolerance. That is, the important surface of precision parts or parts should be higher than the positional accuracy, and the positional accuracy should be higher than the dimensional accuracy.