Brightness level of stainless steel after polishing: According to visual inspection, the brightness of the surface of polished parts is divided into 5 levels:

Level 1: There is a white oxide film on the surface, no brightness;

Level 2: Slightly bright and the outline cannot be seen clearly;

Level 3: The brightness is good and the outline can be seen;

Level 4: The surface is bright and the outline can be seen clearly;

Level 5: Mirror-like brightness.

The general process of mechanical polishing is as follows:

(1) Rough throwing

The surface after milling, EDM, grinding and other processes can be polished with a rotating surface polisher or ultrasonic grinder with a speed of 35,000-40,000 rpm. Commonly used methods include using a wheel with a diameter of Φ 3mm and WA # 400 to remove the white spark layer. Then there is manual whetstone grinding, and the strip whetstone is added with kerosene as a lubricant or coolant. The general order of use is #180 ~ #240 ~ #320 ~ #400 ~ #600 ~ #800 ~ #1000. Many moldmakers choose to start with #400 to save time.

(2) Semi-precision polishing

Semi-finish polishing mainly uses sandpaper and kerosene. The number of sandpaper is: #400 ~ #600 ~ #800 ~ #1000 ~ #1200 ~ #1500. In fact, #1500 sandpaper is only suitable for hardened mold steel (above 52HRC) and is not suitable for pre-hardened steel, because this may cause surface burns on the pre-hardened steel parts.

(3) Fine polishing

Fine polishing mainly uses diamond grinding paste. If a polishing cloth wheel is mixed with diamond abrasive powder or abrasive paste for grinding, the usual grinding sequence is 9 μm (#1800) ~ 6 μm (#3000) ~ 3 μm (#8000). 9 μm diamond abrasive paste and polishing cloth wheel can be used to remove hair-like abrasion marks left by #1200 and #1500 sandpaper. Then use sticky felt and diamond abrasive paste for polishing, in the order of 1 μm (#14000) ~ 1/2 μm (#60000) ~ 1/4 μm (#100000). The polishing process that requires an accuracy of 1 μm or more (including 1 μm) can be carried out in a clean polishing room in the mold processing workshop. For more precise polishing, an absolutely clean space is required. Dust, smoke, dandruff and drool can ruin the highly polished surface you get after hours of work.

Mechanical polishing: Polish with an abrasive belt polishing machine on the roller frame. First use a 120# abrasive belt. When the surface color reaches a certain level, change to a 240# abrasive belt. When the surface color reaches a certain level, change to an 800# abrasive belt. As soon as the surface color arrives, replace the 1200# abrasive belt, and the effect of decorating the stainless steel plate will be lost.