Do you know how to choose the material of plastic film? Listen to the experience of the master shifu.

Do you know how to choose the material of plastic film? Listen to the experience of the master shifu.

The working conditions of the plastic mold are different from those of the cold die. Generally, it must be worked at 150°C-200°C. In addition to being subjected to a certain pressure, it also bears the influence of temperature. According to the different conditions and processing methods of plastic molding die, the basic performance requirements of steel for plastic mold are summarized as follows:

Material requirements

1, enough surface hardness and wear resistance
The hardness of the plastic die is usually below 50-60HRC. The heat-treated die should have enough surface hardness to ensure that the die has enough stiffness. Due to the filling and flow of plastic in the work of the mold to bear greater compressive stress and friction, the mold is required to maintain the stability of shape accuracy and dimensional accuracy, to ensure that the mold has enough service life. The wear resistance of the die depends on the chemical composition of the steel and the heat treatment hardness, so improving the hardness of the die is beneficial to improve its wear resistance.

Do you know how to choose the material of plastic film? Listen to the experience of the master shifu.

2, excellent machinability
In addition to EMD processing, most plastic molding molds need to be cut and repaired by fitters. In order to prolong the service life of cutting tools, improve the cutting performance and reduce the surface roughness, the hardness of the steel used in plastic moulds must be appropriate.

3, good polishing performance
The high – quality plastic products require the cavity surface roughness value is small. For example, the surface roughness of injection mold cavity is required to be less than Ra0.1 ~ 0.25, and the optical surface is required to be Ra&lt. At 0.01nm, the cavity should be polished to reduce the surface roughness. The steel selected for this purpose requires less material impurities, fine and uniform organization, no fiber directionality, and no pitting or orange peel defects when polishing.

4, good thermal stability
Plastic injection mould parts shapes are more complex, difficult to processing after quenching, so should choose as far as possible with good thermal stability, when the mould processing after the heat treatment for small linear expansion coefficient, heat treatment deformation is small, the size of the rate of change caused by the temperature difference is small, the microstructure and the mold size stability, can reduce or no longer carry on the processing, Can ensure the mold dimensional accuracy and surface roughness requirements.

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45, 50 grade carbon steel has a certain strength and wear resistance, after quenching and tempering treatment is used for mold materials. High carbon tool steel and low alloy tool steel have higher strength and wear resistance after heat treatment, and are mostly used in forming parts. However, high carbon tool steel is only suitable for manufacturing small and simple parts due to its large deformation during heat treatment.
With the development of plastic industry, the complexity of plastic products, precision and other requirements are increasingly high, the mold materials also put forward higher requirements. For the fabrication of complex, precise and corrosion-resistant plastic moulds, pre-hardened steels (e.g. PMS), corrosion-resistant steels (e.g. PCR) and low-carbon maraging steels (e.g. 18Ni-250) can be used, all with good cutting, heat treatment and polishing properties and high strength.

Which method is more cost-effective, such as prototype 3D printing or CNC processing?
Which method is more cost-effective, such as prototype 3D printing or CNC processing?

In addition, in the selection of materials must also be considered to prevent abrasion and gluing, such as the existence of relative movement of the two surfaces, try to avoid the choice of the same structure of the material, under special conditions can be plated on one side or nitriding, so that the two sides have different surface structure.