Nowadays, various processing methods appear in front of our eyes. It is because our industry needs these processing methods. Different products and different processing methods are used. For different effects, different processing and non-standard parts are also used. Processing is one of them, so what is the concept and classification of benchmarks in the processing of non-standard parts.
1. Design basis
The point, line, and surface on which the location of certain points, lines, and areas on the part is based on the part drawing.
2. Process benchmark
The benchmark used in the processing and assembly of parts is called the craft benchmark. It includes the following types.
(1) Process reference The reference used to mark the size and geometric tolerance of the process on the process drawing. In essence, the similarities with the design basis are only the basis of the process drawing. The process criteria mostly coincide with the design criteria, and sometimes for processing convenience, some do not coincide with the design criteria but coincide with the positioning criteria.
(2) In the positioning reference processing, the reference on which the workpiece occupies the correct position on the machine tool or in the fixture. If the workpiece is clamped by the direct finding method, the front is the positioning datum; the calibration method is marked by the scribe line, and the line is the positioning datum; the surface of the workpiece and the positioning element that is in contact with the fixture is the positioning datum.
(3) Measurement reference The reference used when the workpiece is measured during or after processing.
(4) Assembling datum When assembling, the datum used to determine the relative position of the part in the component or product.
Post time: Apr-10-2020