1. Choice of nc punch benchmark coarse benchmark Nc punch machine
(1) the choice of rough base: to ensure that the main processing by enough and uniform processing allowance,
which is conducive to ensure the main surface and processing accuracy and physical and mechanical properties of the surface layer.
(2) if the workpiece does not need to be processed surface, you should choose the towel and machining surface have
mutual position precision crack table because of coarse benchmark.
As shown in Figure 1-10, the casting part requires processing and surface B, so it is appropriate to choose the rough surface C as the coarse reference,
and use a three-jaw chuck to hold C, so that the wall of the part is more uniform after the hole processing.
(3) the choice of rough benchmark should be relatively clean and smooth, avoid rabbit to choose a flying edge, pouring appetite surface.
(4) a rough datum can only be used once, and the processed surface should be selected as the fine datum in the training process.
However, for high precision blank, such as the blank made by fine pin, fine forging and other methods,
the same coarse reference can be used repeatedly when the machining surface position is low.
