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Introduction of steel and its properties in injection molds

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Introduction of steel and its properties in injection molds
Click number:- Release time:2019-05-29

In the manufacturing of injection moulds, the material selection of the moulds directly determines the appearance quality of the products and the service life of the moulds. Under the circumstances of the price war and the chaotic market, many moulds factories make profits from microblogging in order to reduce the cost, and occasionally luckily the moulds are still smooth. Inevitably, there are also some sub-optimal, jerry-built, and come back again, which is not worth the loss. Losing his wife and turning his troops into soldiers did not say, delaying the delivery date destroyed the credibility. What factors should be considered in the selection of injection moulds? Dies need to meet the process requirements, while meeting the wear resistance, toughness and other work needs, should also take into account the economic applicability.

Injection mould picture

1.Strength and toughness


3.wear resistance

4..Corrosion resistance: Some plastics such as PVC, POM and PP are 

corrosive and will cause corrosion and rust in the mold cavity. Corrosion-resistant steels include S136H and PAK90.

10-2 Common steel materials for injection molds and their properties

1. ASSAB die steel

(1) 718S and 718H pre-hardened plastic mold steel: good polishing, good wear resistance and high tensile strength. It is often used for high-polishing and high-demand inner mold inserts. Suitable for plastic molds such as PA, POM, PS, PE, PP and ABS. (The rear mold uses a non-design surface)

 Factory hardness (hardened and tempered): 718S---HB290-330. 718H---HB330-370.

Main chemical composition (%): C 0.38, Si 0.3, Cr 2.0, Ni 1.0, Mn 1.4, Mo 

Die steel picture


(2) S136, S136H corrosion resistant mirror mold steel: high purity, high specularity, excellent polishing performance, excellent rust and acid resistance, small heat treatment deformation. Has excellent machinability. Suitable for PVC, PP, PE, PC and PMMA plastics.

Factory hardness (hardened and tempered):
S136---soft annealing to HB215 (hardenable to HRC53). S136H---HB290-330.
Main chemical composition (%): C 0.38, Si 0.8, Cr 13.6, Mn 0.5, V 0.3.

(3) DF2 oil steel (cold work tool steel): This steel has good machinability, high carbon content provides good wear resistance, but low toughness. Used for cutting, bending, gauges, etc.

Factory hardness: soft annealing to HB190.
Main chemical composition (%): C 0.95, Cr 0.6, Mn 1.1, V 1.0, W0.6.

(4) 8407 hot work tool steel: good extensibility, low hardness, medium and low resistance to heat softening resistance, can withstand high working temperature. Mostly used in die-casting molds, extrusion molds, (PA, POM, PS, PE) plastic molds.

Factory hardness: soft annealing to HB185.
Main chemical composition (%): C 0.38, Si 01.0, Cr 5.3, Mn 0.4, V 0.9.
2, Japan Datong company steel

(1) NAK80 high hardness and high polished mirror plastic mold steel

High hardness, excellent mirror effect, good EDM performance, excellent welding performance, suitable for electro-erosion and polishing performance molds.
Factory hardness: HB370-400.
Main chemical composition (%): C 0.15, Si 0.3, Cr 3.0, Ni 3.0, Mn 1.5.

(2) PAK90 mirror anti-corrosion plastic mold steel: suitable for precision molds and high-mirror molds.

Factory hardness: HB300-330.


3, other mold materials

(1) MM30/MM40 high-strength alloy beryllium copper: good thermal conductivity, can cast beautiful curved surface, three-dimensional text (maximum casting 300X300). Suitable for cores and inserts that require rapid cooling or precision casting. High hardness and good cutting performance.

Main chemical composition (%): Be 1.9, Co+Ni 0.25, Cu 97.85.
Factory hardness: MM30: HRC26-32; MM40: HRC36-42. Price: about 280 yuan / lb.

(2) S50C-S55C yellow card medium carbon steel

Suitable for plastic formwork panels and mechanical parts.
Main chemical composition (%): C 0.5, Si 0.35, Mn 0.8,
Factory hardness: HB170-220.

(3)738/738H (Long Kee) pre-hardened plastic mold steel

Suitable for high toughness, high gloss molds.
Main chemical composition (%): C 0.37, Cr 2.0, Ni 1.0, Mn 1.1, Mo0.4.
Factory hardness (tempered): 738---HB290-330. 738H---HB330-370.
【Paper label】:injection molds
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