DIN 1. steel is one kind of plastic mold steel, equivalent to AISI P20 +Ni tool steel. While Nickel, chromium and molybdenium are the alloying elements for hardness and toughness. 1. tool steel is specially designed for plastic mold industry, especially for big steel mold parts.
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Surface Finish: Black Surface, Roughly Machined, Peeled & Turned or as per given requirements.
Usually already pre-toughened, no heat treatment required, if there is no special requirements.
710 to 740 °C for about 2 to 5 hours; then cool slowly of 10 to 20 °C per hour to about 600 °C further cooling in air, This will produce a maximum Brinell hardness of 235.
Harden from a temperature of 840-870°C followed by oil, then quenching in oil/hot bath/air 180~220 °C. Hardness after quenching is around 52 HRC.
Slow heating to tempering temperature immediately after hardening; and minimum time in furnace: 1 hour per 20 mm part thickness; tempering twice is recommended.
1. Molded parts refer to the mold parts that directly contact plastic to form products, such as cavity, core, slider, insert, inclined top, side extraction, etc.
2. The material of the molded parts is directly related to the quality and life of the mold. It determines the appearance and internal quality of the molded plastic products. It must be very cautious. Generally, it should be based on the contract and customer requirements, according to the requirements of the products and molds. Feature selection.
3. The principle of selection of materials for molded parts is based on the type of plastic molded, product shape, dimensional accuracy, product appearance quality and use requirements, production batch size, etc., taking into account the cutting, polishing, welding, etching, deformation, Various properties such as wear resistance, taking into account the economy and the manufacturing conditions and processing methods of the mold, to select different types of steel.
4. For molds for forming transparent plastic products, high-end imported steel with high mirror polishing performance is required for the cavity and core, such as 718 mold steel (P20 + Ni mold steel), NAK80 mold steel (P21 mold steel), S136 die steel (420 die steel), H13 die steel, etc., of which 718 die steel and NAK80 die steel are pre-hardened and no heat treatment is required; S136 die steel and H13 die steel are both annealed and the hardness is generally 160 ~ 200HB, vacuum hardening and tempering treatment is required after rough machining. The hardness of S136 die steel is generally 40 ~ 50HRC, and the hardness of H13 die steel is generally 45 ~ -55HRC (can be determined according to the specific brand).
5. For the molds with high appearance quality requirements, long life and mass production, the selection of molding parts materials is as follows:
a) The cavity needs to use high-grade imported steel with high mirror polishing performance, such as 718 die steel (P20 + Ni die steel), NAK80 die steel (P21 die steel), etc., which are all pre-hardened and do not require heat treatment.
b) The core can be selected from the middle and low grade imported P20 mold steel or P20 + Ni mold steel, such as 618 mold steel, 738 mold steel, 1. mold steel, 638 mold steel, 318 mold steel, etc., all of which are pre- hardened; for production For low-volume molds, imported high-quality carbon steels such as domestic plastic mold steels, S50C mold steels, and S55C mold steels can also be used.
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6. For molds with general appearance quality requirements, the materials of the molded parts are selected as follows:
a) The cavity and core of small and precise molds are made of imported mid-grade P20 mold steel or P20 + Ni mold steel materials.
b) Large and medium-sized molds, the molded plastic has no special requirements for steel, the cavity can be selected from low-grade imported P20 or P20 + Ni steel; the core can be selected from low-grade imported P20 mold steel materials or imported high-quality carbon steel S50C, S55C Etc., domestic plastic mold steel can also be used.
c) For cavities with corroded grains, when eroding pear grains, try to avoid the use of 1. (738 mould steel) grades of P20 + Ni mould steel.
7. For internal structural parts that do not have appearance quality requirements, and the molding materials do not have special requirements for steel, the selection of molding component materials is as follows:
a) For large and medium-sized molds, the cavity can be selected from low-grade imported P20 or P20 + Ni type steel, or imported high-quality carbon steel S55C, S50C or domestic P20 or P20 + Ni type plastic mold steel; the core can be imported Or domestic high-quality carbon steel.
b) For small molds, if the output is higher and the structure is more complicated, low-grade imported P20 or P20 + Ni type steel can be used for the cavity, or domestic P20 or P20 + Ni type plastic mold steel can be used; the core can be made of domestic plastic Die steel.
c) For small molds with simple structure and low output, the cavity core can be made of domestic plastic mold steel or high-quality carbon steel.
8. For molds for forming corrosive plastics such as fluorine and chlorine and various plastics with flame retardant added, if the product requirements are high, imported corrosion-resistant steel can be used, and domestic corrosion-resistant steel can be generally used.
9. For molds that have strong friction and impact plastics for steel, such as molds used to inject nylon + glass fiber materials, imported or domestic H13 with high wear resistance, high thermal tensile strength and high toughness etc.
10. Molded inserts generally use the same materials as the inserted parts. For parts that are difficult to cool or require high cooling effect, the insert material should be beryllium bronze or aluminum alloy.
11. The principles of material selection for movable parts involved in molding are as follows:
a) The transparent parts should be made of high-grade imported steel with good polishability, such as 718 and NAK80.
b) For non-transparent parts, generally, middle-grade imported steel with high hardness and strength should be selected, such as 618, 738, , 638, 318, etc. The surface is nitrided, the depth of the nitrided layer is 0.15 ~0.2mm, and the hardness is 700 ~ 900HV.
c) If the mold requirements are low, low-grade imported steel or domestic steel can also be used. The hardness of nitriding treatment is generally 600 ~ 800HV.
Non-molded parts material selection
1. The mold base material refers to the mold base standard. The template is generally selected from imported S50C or domestic SM45, which requires 160 ~ 200HB, uniform hardness, low internal stress, and not easy to deform. The guide column material is GCr15 or SUJ2, and the hardness is 56 ~ 62HRC. The materials of guide bush, push plate guide post, push plate guide bush and reset rod can be GCr15 or SUJ2 with hardness of 56-62HRC; T8A and T10A with hardness of 52 ~ 56HRC can also be used.
2. The general structural parts in the mold, such as ejector positioning ring, upright, ejector limit block, limit tie rod, lock module, etc., have no special requirements on hardness and wear resistance, domestic SM45 mold steel can be used, normalizing State, hardness 160 ~ 200HB, no need for heat treatment.
3. Sprue bushes, wedge blocks, wear-resistant blocks, slider pressure plates and other parts in the mold that require high hardness, strength and wear resistance should be selected from carbon tool steel or high-quality carbon tool steel, such as T8A tools Steel, T10A tool steel, etc. All such steels need to be quenched to improve their hardness and wear resistance.