Working principle and process of die polishing

In the process of die manufacturing, the forming parts of the die often need to be polished. Mastering the polishing technology can improve the quality and service life of the mould, and then improve the product quality. This paper introduces the working principle and process of die polishing.

1. Mold polishing method and working principle

Generally, oilstone strip, wool wheel and sandpaper are used in die polishing to make the surface of material deform plastically and remove the protruding part of workpiece surface to get a smooth surface, which is usually operated by hand. The method of ultra precision polishing can be used if the surface quality requirements are high. The ultra precision polishing is to use a special grinding tool, in the polishing liquid containing abrasive, to press tightly on the machined surface of the workpiece for high-speed rotation movement. The surface roughness can reach ra0.008 μ m after polishing

2. Polishing process

(1) Rough throw

After finishing milling, EDM, grinding and other processes, the surface can be polished by a rotating surface polishing machine with a rotating speed of 35000-40000 R / min. Then it is hand-made oilstone grinding, strip oilstone plus kerosene as lubricant or coolant. The order of use is 180 × 104m3 → 240 × 104m3 → 320 × 104m3 → 400 × 104m3 → 600 × 104m3 → 800 × 104m3 → 1000 × 104m3.

(2) Semifine throw

Semi fine polishing mainly uses sandpaper and kerosene. The number of sandpaper is as follows:

400#→600#→800#→1000#→1200#→1500#。 In fact, only die steel (above 52hrc) suitable for hardening is used for 񖓿 1500 sandpaper, which is not suitable for pre hardening steel, because it may lead to surface damage of pre hardening steel parts and can not achieve the expected polishing effect.

(3) Fine throw

Diamond paste is mainly used for fine polishing. If diamond grinding powder or paste is mixed with polishing cloth wheel for grinding, the usual grinding sequence is 9 μ m (1800 × 3) → 6 μ m (3000 × 3) → 3 μ m (8000 × 3). 9 μ m diamond paste and polishing cloth wheel can be used to remove the hair like abrasion marks left by 1200 × 1 and 1500 × 1 sandpaper. Then polish it with felt and diamond paste in the order of 1 μ m (14000 × 1) → 1 / 2 μ m (60000 × 1) → 1 / 4 μ m (100000 × 1).

(4) Polished working environment

The polishing process shall be completed in two working places separately, i.e. the rough grinding processing place and the fine polishing processing place, and attention shall be paid to cleaning the sand left on the workpiece surface in the previous process.

Generally, after rough polishing from oilstone to 1200 × sandpaper, the workpiece needs to be transferred to a dust-free room for polishing to ensure no dust particles in the air adhere to the mold surface. The polishing process with a precision of more than 1 μ m (including 1 μ m) can be carried out in a clean polishing room. If a more precise polishing is to be carried out, it must be carried out in an absolutely clean space, because dust, smoke, dandruff and saliva may discard the high-precision polishing surface.

After finishing the polishing process, the surface of the workpiece shall be protected against dust. When the polishing process stops, all abrasives and lubricants shall be carefully removed to ensure that the surface of the workpiece is clean, and then a layer of mould anti rust coating shall be sprayed on the surface of the workpiece.

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