The positioning of CNC milling is to use positioning pins to position the printed circuit board to be processed on the workbench of the milling machine, so as to conveniently and accurately process the shape of the printed circuit board. Require simple and reliable positioning, capable of quickly loading and unloading boards while eliminating chips. The manufacturer of circuit board samples tells you that there are various positioning methods, such as the design of reciprocating workbenches for some milling machines. When one worktable is being processed, the other worktable loads and unloads the board. There is also a method of using two sets of milling positioning pads. When one milling positioning pad is processed on the CNC milling workbench, the other milling positioning pad is loaded and unloaded on the platform. The exchange between the two only takes a few seconds.

　　The CNC milling worktable itself is a positioning plate, which is an aluminum alloy plate fixed with pins and screws. There is a hole and groove positioning system on the worktable below each CNC milling spindle. The milling pad is actually a middle positioning fixture, sometimes referred to as "soft positioning". Require it to be able to locate reliably and quickly unload the board, reduce auxiliary time, and improve production efficiency. Before milling the shape, pre mill grooves on the milling pad that have the same dimensions as the printed circuit board. Generally, the size of the slot width is the actual milling cutter diameter plus 0. 5mm. The groove depth is 2. 5mm. During the machining process, it is a path for the movement trajectory of the milling cutter. Due to the vacuum cleaner's suction, a airflow is generated in the groove to remove chips, making the machining smoother and preventing them from clogging the milling cutter's chip groove, reducing the sharpness. During processing, the milling cutter should be extended into groove 1. 5-2mm. This can prevent the end wear and diameter reduction caused by the continuous cutting of the milling cutter into the board, as well as the deviation in the processing size of the printed circuit board caused by the allowable end diameter reduction in the manufacturing of the milling cutter.

　　Before each batch production, install milling pads on the CNC milling workbench and screw in new nylon threaded plugs. Drill a hole on the threaded plug and install the locating pin to use. The chip removal groove on the milling pad can be milled deeper and wider, which is more conducive to smooth airflow and chip removal, making the processed surface smoother. However, it weakens the support surface, especially when the chip removal groove is close to the positioning pin, which will make the positioning unstable.