Polishing process of injection mold
(1) Rough throwing
The surface after finishing milling, EDM, grinding and other processes can be polished with a rotary surface polishing machine with a speed of 35 000 ～ 40 000 r/min. Then it is manual grinding of oilstone, and the strip oilstone is added with kerosene as lubricant or coolant. The order of use is 180 # → 240 # → 320 # → 400 # → 600 # → 800 # → 1 000 #.
(2) Semifinishing
Semi fine polishing mainly uses sandpaper and kerosene. The number of sandpaper is: 400 # → 600 # → 800 # → 1000 # → 1200 # → 1500 #. In fact, # 1500 abrasive paper is only used for hardening die steel (above 52HRC), not for pre hardening steel, because it may lead to surface damage of the pre hardening steel and cannot achieve the expected polishing effect.
(3) Fine polishing
Diamond grinding paste is mainly used for fine polishing. If the polishing cloth wheel is mixed with diamond grinding powder or grinding paste for grinding, the usual grinding sequence is 9 μ m（1 800#）→6 μ m（3 000#）→3 μ m（8 000#）。 nine μ M diamond abrasive paste and polishing cloth wheel can be used to remove hairlike abrasion marks left by 1200 # and 1500 # sandpaper. Then polish with felt and diamond grinding paste, the order is 1 μ m（14 000#）→1/2 μ m（60 000#）→1/4 μ m（100 000#）。
(4) Polished working environment
The polishing process shall be completed at two working sites separately, i.e. the rough grinding site and the fine polishing site, and the sand particles left on the workpiece surface in the previous process shall be cleaned.
Generally, after rough polishing with oilstone and 1 200 # sandpaper, the workpiece needs to be polished in a dust-free room to ensure that no dust particles in the air stick to the mold surface. The accuracy is required to be 1 μ Above m (including 1 μ m) The polishing process can be carried out in a clean polishing room. If more precise polishing is carried out, it must be carried out in an absolutely clean space, because dust, smoke, dandruff and saliva may scrap the high-precision polished surface.
After the polishing process is completed, the workpiece surface 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 anti rust coating shall be sprayed on the surface of the workpiece.
