Things To Look For In Different Types Of Polishing

1. Matters to note for sandpaper sanding and oilstone grinding of moulds

(1) For hard mould surfaces only clean and soft oilstone sanding tools should be used.

(2) When changing grit levels during sanding, the workpiece and the operator's hands must be cleaned to avoid carrying coarse grit to the next finer level of sanding.

(3) For each sanding operation, the sandpaper should be applied in a different 45° direction until the previous grit level is removed and when the previous grit level is removed, a further 25% of the sanding time must be extended before switching to the next finer grit level.

2. Things to note about diamond grinding and polishing

Diamond grinding and polishing must be carried out under as light a pressure as possible, especially when polishing pre-hardened steel parts and when polishing with fine grinding pastes. When polishing with 8000# polishing paste, a load of 100-200 g/cm2 is commonly used, but it is difficult to maintain the accuracy of this load. To facilitate this, a thin and narrow handle can be made on a wooden bar or a bamboo bar can be made softer by cutting off a portion of it. This will help to control the polishing pressure to ensure that the pressure on the surface of the mould is not too high. When polishing with diamond grinding.

3. Plastic mould polishing should pay attention to matters

The polishing of plastic moulds is very different from the surface polishing required in other industries, strictly speaking, the polishing of plastic moulds should be called mirror processing. It not only has high requirements for polishing itself but also has high standards for surface flatness, smoothness and geometric accuracy. The following precautions should be taken in polishing.

(1) When a new mould cavity begins to be machined, the surface of the workpiece should be inspected first and the surface cleaned with paraffin so that the oil stone surface does not stick to the dirt resulting in the loss of cutting function.

(2) When grinding coarse patterns, you should proceed in the order of difficult first and then easy, especially some difficult dead ends, deeper bottoms should be researched first and finally the sides and large planes.

(3) Part of the workpiece may have more than one group together to polish, to first study the individual workpiece of the rough or sparkle pattern, and then all the workpiece together to smooth.

(4) For workpieces with large or side planes, use an oil stone to remove the rough pattern and then use a flat steel piece to do a transillumination test to check for any unevenness or inversions, which may cause difficulties in removing the part from the mould or strain the part.

(5) In order to prevent the mould workpiece from being backed up or having some laminated surfaces that need to be protected, use a saw blade to stick or use sandpaper to stick on the edges, this will give the desired protection.

(6) Grind the mould plane with a back and forth pull, drag the handle of the oil stone as flat as possible, do not exceed 25 °, because the slope is too large, the force from the top downward punch, easy to lead to the research of many rough lines in the workpiece.

(7) If the plane of the workpiece is polished with copper or bamboo sheets pressed against the sandpaper, the sandpaper should not be larger than the area of the tool, otherwise it will be studied to places that should not be studied.

(8) Try not to use the grinding machine to repair the parting surface, because the parting surface trimmed by the grinding wheel head is relatively rough and has waves of unevenness, if necessary, the grinding wheel head must be glued to repair to concentricity balance.