​CNC machined parts In the process standard design, the correct selection of positioning data has a crucial impact on ensuring the requirements of CNC machined parts and rationally arranging the processing sequence.

The positioning reference is divided into fine reference and rough reference: the rough reference uses the unprocessed surface on the blank as the positioning reference. The fine datum takes the processing plane as the positioning datum.

1. Criteria for choosing a precise benchmark

1. Baseline coincidence criterion: The processed surface design data should be as accurate as possible to prevent positioning errors caused by data misalignment.

2. Consistent datum criteria: In order to ensure the relative positioning accuracy between the machined surfaces of parts, as many surfaces as possible on CNC machined parts should be processed with the same set of fine datums as much as possible.

3. Mutual reference criterion of the workpiece processing surfaces: the repeated processing method of the two processing surfaces can be used as a cross-reference.

4. Self-based benchmark criterion: Some surface finishing processes require small and uniform machining tolerances, and the machined surface itself is often used as the precision benchmark.

The four criteria for selecting a good benchmark mentioned above are sometimes impossible to meet at the same time, and must be decided according to the actual situation.

2. Criteria for choosing a rough benchmark

1. The rough datum should be used when machining CNC machined parts for the first time. Whether the rough datum is selected correctly is not only related to the processing of the first process, but also has a great impact on the entire process of the workpiece.

2. Reasonable allocation standard of processing tolerance: the processing allowance on the surface of the workpiece should be kept uniform, with the important surface as the rough benchmark.

3. Standards for easy clamping: In order to ensure stable positioning and reliable clamping of CNC machined parts, the approximate reference point selected is required to be as smooth and clean as possible, free from lightning strikes, and a sufficient supporting area is allowed for forging incisions or other defects.