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Elementary Analysis Of Basic Properties Of Plastic Mould Steel Oct 30, 2017

Plastic mold working conditions and cold die is different, usually in one hundred and fifty degrees Celsius to two hundred degrees Celsius work, in addition to a certain pressure, but also to bear the temperature influence. According to the plastic molding mold use conditions, processing methods, the plastic mold steel basic performance requirements are summarized as follows:

Good machinability

Most plastic mold, in addition to the EMD processing, the need for a certain cutting and fitter repair. In order to prolong the service life of cutting tools, enhance the cutting performance and reduce the surface roughness, the hardness of the plastic mould steel must be appropriate.

Two. Good thermal stability

The shape of parts plastic injection mold are very complex and difficult to machining after quenching, therefore, should try to use materials with good thermal stability. When the mold molding after heat treatment, because of small linear expansion coefficient, heat treatment deformation is small, the size change of the temperature difference caused by the rate of small, microstructure and die size stability, can be reduced or no processing, to ensure that the mould size accuracy and surface roughness requirements.

Three. Good polishing properties

Injection molding high quality requirements, the cavity surface roughness value. For example, the surface roughness value of the injection mold cavity is less than Ra0.1-0.25, and the optical surface requires Ra<0.01nm. The cavity must be polished to reduce the surface roughness value. Therefore, the choice of steel materials requires less impurities, microstructure and uniform fiber direction, polishing should not appear pitting or orange skin defects.

Four. Adequate surface hardness and wear resistance

Plastic mold hardness is usually below 50-60HRC, after heat treatment should have sufficient surface hardness, to ensure the mold has sufficient rigidity. Mold in the work, due to the filling and flow of plastic to bear greater compressive stress and friction, require mold to maintain the stability of shape accuracy and dimensional accuracy, to ensure that the mold has sufficient service life. The wear resistance of the mould depends on the chemical composition of the steel and the hardness of the heat treatment. Therefore, increasing the hardness of the mould is beneficial to enhance the wear resistance of the mould.

Five.50 grade carbon steel has a certain strength and wear resistance

Quenched and tempered for mold materials. High carbon tool steel and low alloy tool steel after overheating treatment have higher strength and wear resistance, and are used for forming parts. However, the high carbon tool steel is only suitable for manufacturing parts with small size and simple shape because of its large heat treatment deformation.

With the development of the plastic industry, the complexity and precision requirements of plastic products is more and more high, also put forward higher requirements on the injection mold material. For the complexity of manufacturing, precision and corrosion resistance of plastic mold, the pre hardened steel (such as PMS), corrosion resistant steel (such as PCR) and low carbon maraging steel (such as 18Ni-250), which has good machining, heat treatment and polishing performance and high strength.

In addition, in the choice of materials, we must consider the prevention of abrasion and scuffing, such as two surface relative motion, is avoided in structure of the same material, special conditions can be side plating or nitrided, so that the two sides with different surface structures.