the following sheet lists the different types of steel available for mold plates together with a brief account of their properties and uses*
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Mold steel applications |
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Category |
Uses |
Standard |
Comments |
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Low-carbon, also known as plain plates, carbon or mild steel |
support locating rings |
BS907 (EN8J AISI 1020 DIN 1.180.5 |
Used for economy in noncritical applications |
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Prehardened or pretoughened alloy too] steels |
Cavities, punches and cores |
BS4569 BP20 AISI P20 DIN 1.2713 |
Alloy tool steel used unhardened. Can be locally heat-treated |
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Fully hardening alloy tool steels |
High volumes where high quality, strength and hardness are required for cavities and cores |
BS4569 (EN30B) AISI H13 DIN 1,2.34.3 |
High-quality tool steel. First choice for long-running jobs |
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Stainless steel |
Used for corrosion resistance to protect against corrosive materials such as PVC |
13S (E.N57) AISI 420 SS DIN 414 SS |
Stainless steels contain up to 18% chromium mu\ hence have worse heat transfer |
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High-carbon—high- chrome |
Cavities and cores where high levels of hardness are required |
BS (EN308) AISJ D2DINL260L |
Very hard when heat treated* Used for small parts. Prone to stress cracking |
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Nitriding steels |
Areas of high wear. Sliding surfaces, ejector pins and sleeves |
BS907 722M24 AISI HI3 DIN 1.2307 |
Extensively used for small sliding parts |
The most frequently used standard is the AISI, which stands for the American Iron and Steel Institute. By international agreement the AISI designator system has been adopted and hence literature will refer to this standard. All AISI specifications have an initial identification letter, which helps to identify steel types as shown in the following
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AISI steel designations |
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Identification letter |
Type of steel |
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A |
Air hardening steels |
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C |
Carbon steels |
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D |
High-carbon-high- chrome steels |
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F |
Carbon—tungsten steels |
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H |
Hot work die steel (H1-H19 chromium base) (H20-H.39 tungsten base) (H40—H49 molybdenum base) |
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L |
Low alloy steels |
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M |
Molybdenum base steels |
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O |
Oil hardening steels |
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P |
Mull steels (PI—P19 low-carbon) (P20—P39 other types) |
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s |
Shock-resistant steels |
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T |
Tungsten-base steels |
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W |
Water hardening steels |
The most commonly used steels for injection molding tools are as shown the following . The alloy steels list steel will machine readily (conventional machining and EDM) and will support high levels of polish. They are also suitable for texturing using EDM and photo etch techniques.
These are not the only steels used for injection mold tools but they do represent those used for the majority of applications. Specialist steels may be used for more demanding applications, e.g.” stainless steel for corrosion resistance, and high-carbon-high-chrome to achieve ultra-hard cavity inserts.
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AISI designated mold steels |
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Type of steel |
AISI No. |
Comments |
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Mild Steel |
MSI 1020 |
For backplanes, support plates, support register rings and ejector bars |
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Nickel Chrome Alloy |
AIS] H13 |
Used unhardened for cavity backing plates where high loads are likely and for medium-quantity jobs for cavities and cores, or for plates likely to suffer bruising, runner system plates and stripper plates on mutilate tools. Used hardened for high-quality, long-running jobs for all cavities, cores and punches, Hardness value 48-52 HRc |
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Nickel Chtome Alloy |
AISI P20 |
Pretoughened steel used for medium-volume work. Material can be machined in this state. It is about halfway between the unhardened and hardened grades of H13 in toughness and hardness. Used for cavities and com Hardness value 28-32 HRc |