1. Easy to demolding
The surface disturbance of the die and its components is the main factor leading to the demolding, especially for the steel dies with lower surface hardness. The surface disturbances are due to the properties of the mold material itself (such as porosity), or the damage of the mold after the long service life (influence of the resin).
2. High wear resistance, corrosion resistance and oxidation resistance
For plastic molds due to plastic molding process is carried out at a certain temperature, the mold's working temperature is generally below 250 °C, and because some plastics will decompose hydrogen chloride or hydrogen fluoride gas during the heating process, and these corrosive gases will cause corrosion on the plastic mold surface. At the same time, most plastics are filled with a certain amount of fillers. For example, glass fibers and powder fillers will cause wear on the surface of plastic molds. The increase of the surface roughness after corrosion will aggravate the wear and tear of the die.
3. High hardness and stability
These properties are ideal for plastic injection molds with textured surfaces and for processing engineering plastics (including polyamides and polyarylsulfone/ polysulfone).
These problems encountered in injection moulds can be solved by PVD coating. After coating, the injection mold has the following properties:
(1) High wear resistance, the molds service life is greatly extended.
(2) The flow time of the rubber is longer, and the filling effect is better.
(3) The surface quality of plastic products is improved and the defective rate is reduced.
(4) It is easier to demolding and even avoiding the use of mold release agents.
(5) Effectively prevent corrosive raw materials from erosion of mould substrate.
(6) The mold is easy to clean, and the cleaning cycle is longer.
In addition, plastic molds are usually tempered at low temperature. Therefore, PVD coatings usually are not suitable for high temperature treatment. In this case, the low temperature PVD coating process should be adopted to ensure that the substrate of the mold is not annealed.
The TiN film is deposited after the conventional heat treatment to improve the wear resistance. And due to the improvement of the resistance to salt spray corrosion, the mold surface will not have pitting corrosion and resulting in sticky during demolding. The surface of the plastic parts is smooth, the quality is good and the service life is increased by 2~4 times than that of the original ones, and the production benefit is improved. With the PVD-treated screw, the resin stripping performance is good, and also reduces the resin burned.