In order to obtain high quality polishing effect, the most important thing is to have high quality polishing tools and accessories such as oilstone, sandpaper and diamond grinding paste. The choice of polishing procedure depends on the surface condition after the initial processing, such as mechanical processing, electric spark processing, grinding and so on. The general process of mechanical polishing is as follows:

(1) After rough polishing by milling, edM, grinding and other processes, the surface can be polished by a rotary surface polishing machine or ultrasonic grinding machine at a rotational speed of 35 000-40 000 RPM. The commonly used method is to remove the white edM layer using a wheel with diameter of φ 3mm and WA # 400. This is followed by hand grinding of whetstone, strips of which are added with kerosene as a lubricant or coolant. Generally the use of this order # 180 ~ # 240 ~ # 320 ~ # 400 ~ # 600 ~ # 800 ~ # 1000. Many die makers choose to start with #400 to save time.

(2) Semi-fine throwing semi-fine throwing mainly use sandpaper and kerosene. Sandpaper the number in the order: # 400 ~ # 600 ~ # 800 ~ # 1000 ~ # 1200 ~ # 1500. In practice #1500 sandpaper should only be used with quenchable die steel (52HRC and above) and not with pre-hardened steel as this may cause surface burns on the pre-hardened steel.

(3) Fine casting fine casting mainly uses diamond grinding paste. If the polishing cloth wheel is mixed with diamond grinding powder or grinding paste, the usual grinding sequence is 9μm (#1800) ~ 6μm (#3000) ~3μm (#8000). 9μm diamond grinding paste and polishing cloth wheel can be used to remove hair marks left by #1200 and #1500 sandpaper. Then the polishing was performed with adhesive felt and diamond grinding paste in the order of 1μm (#14000) to 1/2

Optical cold processing operation 8 μm (#60000) ~1/4μm (#100000). The polishing process with accuracy above 1μm (including 1μm) can be carried out in a clean polishing room in the mold processing shop. For more precise polishing, an absolutely clean space is required. Dust, smoke, dandruff, and drool can ruin a highly polished surface after hours of work.