Can I use H13 or S7 steel for mold that produces class A surfaces finished product? If Yes, what are the risks? If NO, what are the benefits?

Like Class A finisged, the mold steel should be with good polishing ability, like DIN.12738,S136, NAK 80,Gest 80. Like the H13 and S7, sometime will be used in PET preform molds bacause of their hardness.

what if I had to do an Engineering change after I hardened and textured the mold ?

I already know that H13 steel is often chosen because it is excellent for diamond polishing. Mold for lenses and other plastic parts that require mirror finishes . It can be hardened to Rockwell 52 and is very versatile, with high hardness, toughness, and high temperature strength.

When molds are built out of H13, S7, A2, D2, 420 stainless steel, or other pre-hardened steels, the differences in hardness and/or chemistry provides a resistance against the texturing process.

H13… suitable for the mould life bigger than 500K.

suitable for hard engineering material such like ABS, PC, PMMA, PS, POM, PA or it is suitable for some material which added the glass fiber.

if I am molding PVC or PLA material or other acidic plastic resin , I rather choose stainless instead of H13

agin
what if I had to do an Engineering change after I hardened and textured the mold ?

Hi,Amer, the hardeness of H13 is 48-52 HRC, but if the resin is PVC or PLA, it is better to use 420-Stainless steel or 1.2083 hardened or 1.2085 hardened, becuse those types of steel is more corrosion resist, and the A and B plate for the mould better choose P20.
Ater hardened and textured the mold, which kind of engineering change do you have to do? You want to polish or EDM or other procesing.

Nitriding decreases the corrosion resistance
of stainless steels and is generally not recommended for stainless steels.

If you already hardened the mold
Why do you want Nitriding?
I only use surface treatments for P20 steel
Nitrading is ok but DYNA-BLUE is the best
Use surface treatments only if you are molding
a glass filled material the P20 mold should last up to 300,000 shot
do not use it for a glass filed Nylon use H13.
do not use Carburizing because the hardened surface
will be too deep, hard to weld it and hard to change it.

A high hard P20 requires a special DYNA-BLUE treatment it is different from the standard P20 steel.

420 stainless steels
Welding: Not commonly welded due to its air hardening characteristics. Welding may be performed after preheating to 300-400 F (149-204 C) with post weld tempering at temperature for 2 hours . Filler metal should be AWS E/ER420.

Annealing 1550-1650 F (843-900 C), slow furnace cooling

Tempering 300-400 F (149-204 C), air cool for maximum hardness (Rc 52) and corrosion resistance.

Hardening Soak at 1850-1950 F (1010-1066 C) at quench in heated oil.

what is heat treatment cycle for 420-Stainless steel and i wanted to tempring temprature if I wanted to do nitriding , is any hardness get drop for 420 SS.?

Hi Amer,
Mold modification for hardened mould surch as H13 HRC50, only way is to wirecut where you need to change and put a new insert, but this have to appear a new line on the molding part, if no accept the line you have to remake the mold part which need to change.
Welding can not be use for hardened mould, it will much reduce mold life.

can i use any other materials in the place of h13 for aluminum extrusion process?