Brief Analysis of Performance Requirements of Steel for Plastic Injection Mould

According to the forming method, plastics can be divided into thermoplastics and thermosetting plastics. Thermosetting plastics, such as bakelite powder, are permanently formed by pressing under heating and pressure. Bakelite moulds are periodically subjected to pressure and continuously heated at 150-200 degrees. Thermoplastics, such as polyvinyl chloride, are usually formed by injection moulding. Plastics are heated in a separate heating chamber and then injected into colder moulding chambers in a softening state to exert pressure, thus bringing about cold and hard moulding.

The manufacturing cost of plastic moulds is high, and the material cost only accounts for a small part of the cost of moulds. Therefore, when choosing steel, steel with good technological performance, stable performance and long service life should be preferred. Specifically, the following requirements are put forward for plastic moulds:

1. Excellent machinability: The geometric shape of the cavity of plastic mould is very complex, and it requires processing deep holes, deep grooves and other difficult-to-machine parts. Steel must have the ability

of easy cutting. When choosing steel, if other conditions can be satisfied, it is the basis for the final selection.

2. Excellent polishing performance: no matter what kind of plastic mould, the allowable surface roughness of its cavity is very small, almost all of them require mirror gloss. To achieve mirror gloss, steel must have good hardness. First of all, the impurities in steel should be as few as possible, and there should be no bubbles, and the microstructures are uniform, in large quantities. Surface roughness is also an important condition for moulds used in production.

3. Good surface corrosion machinability: Many moulds require that the surface of the moulded plastic parts be patterned with various other materials, such as leather, silk, cloth, fine patterns, etc. This requires that the quality of the steel is fine and uniform, otherwise the effect of corrosion is not good.

4. Good wear resistance and toughness: Plastic moulds are subjected to thermal alternating load for a long time, and also to friction for a long time. If only one side of friction resistance is considered, and the other side of periodic alternating heat load is not considered, the high carbon high alloy steels manufactured by cold-punching moulds will inevitably have insufficient toughness and cause cracking.

5. Good quenching performance and small deformation: most of the cavity parts of plastic moulds must be heat treated, which requires steel to have good hardenability and small deformation. Generally, thermoplastic moulds can be processed by tempering and pre-hardening, while thermosetting plastic moulds must be hardened.

PTJMould Industrial Company Limited, established in 2010, is a leading plastic injection molding manufacturer in China. PTJMould specializes in plastic mould production for household appliances, medical equipments, electronic equipments, safety equipments as well as monitoring system.

The company has over 15000 square metres factory. With plastic injection tooling divisions possessing different machinery and expertise, PTJMould offers tools from small and precise mobile phone parts to as big as automotive parts. Our tools are mainly exported to U.S.A., Europe, Japan and UK. PTJMould’s diversification strategy and full service has won compliment from customers all over the world.

Our mission is to provide our customers high quality moulding products and services. We aim to exceed our customers’ expectations of pricing, quality and on-time delivery. To achieve our mission, PTJMould:

• Commits to continually improve employee skills and efficiency,
• Provides our employees a clean and safe working environment,
• Upgrades machine technology and support equipment through a strict maintenance program, and
• Maintains customers’ tooling to its highest peak of performance

For more about custom manufacturer of plastic molding products,please visit https://www.plastics-moulding.com/

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