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Do you know how to choose plastic mold materials? These tips you need to know
Release time:2023-10-31
Do you know how to choose plastic mold materials? These tips you need to know
Plastic mold working conditions and cold press mold is different, generally must be in one hundred and fifty degrees Celsius to two hundred degrees Celsius to work, in addition to a certain pressure, but also to withstand the effects of temperature. Now according to the plastic molding mold conditions of use, different processing methods, the basic performance requirements of plastic mold steel is summarized below:
I. Excellent machinability
Most plastic molding molds, in addition to EDM processing, but also need to carry out a certain amount of cutting and clamp repair. In order to extend the service life of cutting tools, enhance cutting performance, reduce surface roughness, plastic mold steel hardness must be appropriate.
II. Good thermal stability
Plastic injection mold parts are often complex in shape, hard to process after quenching, therefore, should try to use with good thermal stability. When the two-color mold molding process after heat treatment, due to the coefficient of linear expansion is small, heat treatment deformation is small, the temperature difference caused by the size of the rate of change is small, the metallurgical organization and mold dimensional stability can be reduced or no longer be processed, you can ensure that the mold dimensional accuracy and surface roughness requirements.
III. Good polishing performance
High-quality two-color injection molded plastic products, the requirements of the cavity surface roughness value is small. For example, the injection mold cavity surface roughness value is required to be less than the level of Ra0.1-0.25, the optical surface is required to Ra<0.01nm, the cavity must be polished to reduce the surface roughness value. To this end, the choice of steel requires less material impurities, the organization of micro-fine uniform, non-fibrous directionality, polishing should not appear pitting or orange peel defects.
IV. Sufficient surface hardness and wear resistance
Plastic mold hardness is usually below 50-60HRC, after heat treatment of the mold should have sufficient surface hardness to ensure that the mold has sufficient rigidity. Mold in the work, due to the filling and flow of plastic to withstand greater pressure and friction, the mold is required to maintain shape accuracy and dimensional accuracy of the stability of the mold to ensure that the mold has sufficient service life. Mold wear resistance, depending on the chemical composition of the steel and heat treatment hardness, therefore, improve the mold hardness is conducive to enhance its wear resistance.
V.50 grade carbon steel has a certain strength and wear resistance
After tempering treatment is mostly used for mold materials. High-carbon tool steel, low alloy tool steel after heat treatment has high strength and wear resistance, more for molding parts. However, high carbon tool steel because of its heat treatment deformation, only for the manufacture of small size, simple shape molding parts.
With the development of the plastics industry, the complexity of plastic products, precision and other requirements are increasingly high, the two-color injection mold materials also put forward higher requirements. For the manufacture of complex, precise and corrosion-resistant plastic molds, can be used pre-hardened steel (such as PMS), corrosion-resistant steel (such as PCR) and low-carbon martensitic aging steel (such as 18Ni-250), have a better cutting and processing, heat treatment and polishing performance and high strength.
In addition, in the selection of materials, but also to consider the prevention of abrasion and gluing, such as the existence of two surfaces of the relative movement, then try to avoid the selection of the same organizational structure of the material, in special circumstances, one side of the plating or nitriding, so that the two sides of the surface with a different structure.
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