Technical analysis of PCB (synthetic stone) numerical control milling machine (PCB numerical control milling machine technology has tool direction, compensation method, frame structure, positioning direction, tool point, etc. are all very important aspects to ensure milling accuracy.)
　　1. Tool direction and compensation method When the milling cutter cuts into the synthetic stone slab, one side to be cut is facing the cutting edge of the milling cutter and the other side is always facing the cutting edge of the milling cutter. The machined surface facing the milling cutter is smooth and smooth, and the dimensional accuracy is very high. The spindle always rotates clockwise! Therefore, no matter the spindle is fixed on the worktable or the worktable is fixed on the spindle, when milling the external contour of the printed circuit board PCB, the tool shall be moved counterclockwise. This is what we usually call up milling. When milling the frame or slot inside the PCB, the forward milling method is used. Milling plate compensation refers to that when milling plate, the machine tool automatically installs the set value to let the milling cutter automatically offset half of the set milling cutter diameter, that is, the radius distance, with the center of the milling line, so that the milling profile is consistent with the program setting. At the same time, if the machine tool has the compensation function, it is necessary to pay attention to the compensation direction and the command to use the program. If the compensation command is used incorrectly, the PCB will have more or less dimensions equivalent to the length and width of the milling cutter diameter.

2. Frame and lower tool point
　　The manufacturing of the frame belongs to the early manufacturing of PCB. The frame design not only has an impact on the uniformity of electroplating, but also has a certain impact on the milling plate. If the design is not good, the frame is easy to deform or some small pieces of small waste are generated when milling the plate, which will block the dust suction pipe or break the high-speed rotating milling cutter. The frame deformation, especially when positioning the milling plate externally, will cause the deformation of the finished plate, Also, good selection of cutting point and processing sequence can make the frame maintain the maximum strength and speed. If the selection is not good, the frame is easy to deform and the PCB will be scrapped.

3. Positioning method and cutting point
　　The positioning methods can be divided into two types; One is internal positioning, the other is external positioning. Positioning is also very important for process developers. Generally, the positioning scheme should be determined during the pre fabrication of PCB.

　　Internal positioning is a general method. The so-called internal positioning refers to selecting the mounting hole, plug hole or other nonmetallic holes in the PCB as the positioning holes. The relative position of the holes shall be on the diagonal and the holes with large diameter shall be selected as far as possible. Metalized holes shall not be used. Because the difference in the thickness of the coating in the hole will affect the consistency of the positioning hole you selected. At the same time, it is easy to damage the coating in the hole and on the edge of the hole surface when taking the board. The fewer the pins, the better. Generally, 2 pins are used for small plates, and 3 pins are used for large plates. Its advantages are accurate positioning, small deformation of plate shape, high accuracy, good shape, and fast milling speed. Disadvantages: There are many kinds of holes in the plate, and it is necessary to prepare all kinds of pins with various diameters. If there is no positioning hole available in the plate, it is necessary to discuss with the customer about adding positioning holes in the plate during early fabrication.