What are the selection principles of turning milling composite machining process benchmark
1. Selection principle of rough datum
(1) The principle of uniformity of important surface margins. First, it is necessary to ensure that the important surface of the workpiece has a small and uniform machining allowance.
(2) Principle of mutual position requirements of workpiece surfaces. The mutual position requirements of the machined surface and the unmachined surface on the workpiece must be guaranteed, and the unmachined surface is taken as the rough machining datum.
(3) The principle of sufficient margin. If all surfaces on the part need to be machined, the surface with small machining allowance shall be taken as the rough datum.
(4) The principle of reliable positioning. As a rough datum plane, a relatively reliable, smooth and clean surface shall be selected to ensure accurate positioning and reliable clamping.
(5) Non reuse principle. The coarse datum positioning accuracy is low. The same dimension direction can only be used once and cannot be used repeatedly, otherwise the positioning error is too large.
2. Selection principle of precise benchmark
When selecting the precision base, the key point to be considered is how to reduce the error and ensure the precision of Dongguan turning milling composite processing and convenient installation. The selection principles of precise benchmark include:
(1) Principle of datum coincidence. The design datum of the part shall be selected as the datum as far as possible to avoid the misalignment error of the datum.
(2) The principle of unified datum. The precision datum selected as far as possible shall be used for positioning and processing each surface to ensure the mutual position accuracy between the surfaces.
(3) Self reference principle. Some finishing or finishing processes require small and even machining allowance, so the machined surface itself should be selected as the finishing benchmark.
(4) The principle of mutual reference and repeated processing. Some surfaces with relatively high mutual position accuracy requirements can be guaranteed by the principle of mutual reference and repeated turning milling in Dongguan.
(5) Positioning reliability principle. The precision datum shall be flat and smooth, with certain accuracy, to ensure simple positioning, easy installation and reliable clamping.
The selection principles of benchmarks are summarized from production practice, and must be analyzed and applied in combination with specific production conditions, production types and processing requirements.