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Molded-Micro Part April 10, 2011

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วิบุญ ตั้งวโรดมนุกูล (2010) Molded-Micro Part, วารสารส่งเสริมเทคโนโลยี, December 2010-January 2011, Vol.37 No.214, 79-83.


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In summary of metals for Mold & Die applications November 13, 2009

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General structures:
1. Base of the machine
Cast iron (Gray cast iron — JIS: FC 25 (tensile str. 25 kg/mm2) or FC 30 (tensile str. 30 kg/mm2))
– cheap; machinability; castability; low thermal expansion; high compressive strength; vibration absorption

2. Small tensile load structures
Mild steel (low-carbon steels — less than 0.25%C by weight; SS 40 and SS 41)
– formability; weldability

3. Backing plate, Spacer block and Insert
Medium-carbon steel (S 45 C or S 50 C)


Plastic mold:
1. Hardening steels (AISI P2 and P4; carburizing on the surface: 58-62 HRC; inner core: 25-35 HRC)
– wear resistance; impact resistance

2. Plastic mold steels (AISI P21, P20 or P20S (high S for high machinability))

3. Stainless steels (Martensitic stainless steels; 11.5-18%Cr; rapid quenching to avoid Cr3C2 on the grain boundary; JIS: SUS 420J2, 431 or 440C)
– corrosion resistance; for high corrosive plastic injection mold (eg. PVC)

4. Aluminum alloy (A7079-61)
– corrosion resistance (good for PVC mold); thermal conduction; light weight

5. Be-Cu alloy
– high thermal conductivity; cooling time can be reduced by 40% in plastic injection mold; reduce sink mark and distortion on the plastic part


Stamping die:
1. Tool steels (JIS: SK 1 to SK 7; 0.6-1.4%C; water quenching: 65-68 HRC)
– wear resistance; impact resistance; not good for high temperature process

2. Alloy tool steel cold work:
- Low-alloy steels (JIS: SKS 3; oil quenching)
- Medium-alloy steels (JIS: SKD 12; air quenching) — wear resistance
- High C-Cr alloy steels (JIS: SKD 11) — wear resistance; ductility
- High speed tool steels (W-Mo-Cr-Co play the important role):
JIS: SKH 51; SKH 52; SKH 55; SKH 59
- Cemented carbide (85-90 HRA) — for cutting and punching sheet metal; wear resistance; low impact resistance
- HZ alloy (Cu-Al-Be alloy; tensile str. 500-650 N/mm2; elongation 0.5-2.0%; 180-400 HB) — wear resistance; good for stainless steel forming; no scratch left on the formed sheet metal


Hot forging and die casting:
1. Alloy tool steel hot work :
- JIS: SKD 5, SKD 61 and SKD 62


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