The length of the spinneret of the melt-blown fabric mould varies from 300mm, 600mm, 1.2m, 1.6m, or even more than 3m. The size of the aperture is usually 0.1mm~0.3mm. The number of holes in each spinneret varies from more than 300 to several thousand.

At present, the perforating technology of spinneret is basically drilling and laser processing. These processing methods may cause burr or rough surface in the small hole, which may cause blockage in the continuous flow injection, or affect the flow rate of melting and spraying, thus forming crystals, and the service life is also very low. The holes must be polished before the spinneret can be used.

So, how are these microholes polished? Artificial polishing is of course not realistic, one hole cast 2-3 minutes, 200 holes? A worker could not throw a spinneret a day. For porous polishing such as spinneret, the current polishing method is generally abrasive flow grinding.

Abrasive flow polishing porous workpiece: using soft abrasive (abrasive particle size is very small, abrasive semi-fluid state), after extrusion, directly into the workpiece hole, and then out. Such repeated circulation flow, grinding and polishing effect. After polishing the spinneret, the inner hole can achieve the mirror effect. Even if again porous, also be a polishing, a 600mm spinneret board, only need ten minutes to be able to finish polishing. There are many holes in the melt - jet spinneret and the aperture is small.

Therefore, it is necessary to use special fluid grinding equipment with micro holes and diamond soft abrasive with smaller particle size for polishing the melt jet spinneret. Let's look at the process diagram of the abrasive fluid polishing of the spinneret.

At present, there are many factories in China that seem to be able to make molten spray die, which is also the reason why ordinary masks have been easy to buy. However, few N95 masks are on the market. This is because there are very few companies that can make injection moulds with an aperture of 0.1-0.15mm. Other masks melt spray die head of the micro hole diameter is generally 0.2-0.3mm, seemingly not big difference, but the processing difficulty and polishing difficulty is a world of difference!