Polishing Knowledge-2.Common tools and process flow of abrasives polishing

Common tools and specifications for mold polishing

The commonly used tools for mold polishing are: sandpaper, whetstone, felt wheel, grinding paste, alloy file, diamond grinding needle, bamboo chip, fiber whetstone, and circular rotary grinding machine.

sandpaper:150#,180#,320#,400#,600#,800#,1 000#,1200#，1500#;

whetstone:120#,220#,400#,600#;

felt wheel:Cylindrical, conical, square beak;

grinding paste:1#(white) 3#(yellow) 6#(orange) 9#(green) 15#(blue) 25#(brown) 35#(red) 60#(purple);

alloy file:Square, round, flat, triangular and other shapes;

diamond grinding needle:Generally 3/32 handle or 1/8 handle, there are round wave, cylindrical, long straight cylindrical, oblong cone;

bamboo chip:Various shapes are suitable for the operator and the shape of the mold, and the function is to press the sandpaper and grind it on the workpiece to achieve the required surface roughness;

fiber whetstone:200#(black) 400#(blue) 600#(white) 800#(red)

 polishing process

1. Rough polishing The surface after finishing milling, EDM, grinding and other processes can be polished by a rotating surface polishing machine with a rotating speed of 35 000-40 000 r/min. Then there is manual whetstone grinding, strip whetstone with kerosene as a lubricant or coolant. The order of use is 180#→240#→320#→400#→600#→800#→1 000#.

2. Semi-fine polishing Semi-fine polishing mainly uses sandpaper and kerosene. The number of sandpaper is as follows: 400#→600#→800#→1 000#→1 200#→1 500#. In fact, #1 500 sandpaper is only suitable for hardening die steel (above 52 HRC), not for pre-hardened steel, because it may cause damage to the surface of the pre-hardened steel and cannot achieve the expected polishing effect.;

3. Fine polishing Fine polishing mainly uses diamond abrasive paste. If a polishing cloth wheel is used for grinding with diamond grinding powder or grinding paste, the usual grinding sequence is 9 μm (1 800#)→6 μm (3 000#)→3 μm (8 000#). 9 μm diamond paste and polishing cloth wheels can be used to remove hair-like scratches left by 1 200# and 1 500# sandpapers.

Polished work environment

The polishing process should be completed in two separate work sites, namely, the rough grinding process site and the finishing process site are separated, and attention should be paid to cleaning the sand particles remaining on the surface of the workpiece in the previous process. Generally, after rough polishing from whetstone to 1 200# sandpaper, the workpiece needs to be transferred to a clean room for polishing to ensure that no dust particles in the air stick to the surface of the mold.

The polishing process that requires precision above 1 μm (including 1 μm) can be carried out in a clean polishing chamber. After the polishing process is completed, the surface of the workpiece should be protected from dust. When the polishing process is stopped, all abrasives and lubricants should be carefully removed to keep the surface of the workpiece clean, and then a layer of mold anti-rust coating should be sprayed on the surface of the workpiece.