Precision machining process-part positioning and datum 1. Benchmark Benchmark refers to the points, lines, and surfaces used to determine the geometric relationship between the geometric components of the production object. For a machine part, the datum is the point, line, and surface on which the positions of other points, lines, and surfaces on the part are determined. In the decision-making and processing process of mechanical parts, which points, lines, and surfaces are selected as benchmarks according to different requirements are one of the main components that simply affect the processing technology of the parts, the dimensions between the surfaces, and the accuracy of the positions. Based on the difference between the results and the application, the benchmarks can be divided into two categories: decision-making benchmarks and process benchmarks. (1) Decision-making Read more