Hardened mold steels

The structure is manufactured from pre-hardened mold steel such as 1.2312 or from a corrosion-resistant steel 1.2085, while the splits are available in different materials. Here, case-hardening steels and depth-hardened steels such as 1.2343 are available. 

Type Corrosion resistant plastic mold steel (good machinable) Tempered mold steel Tempered and hardened mold steel (highly polishable and etchable)... 

In general terms, it can be said that each type of material has its own wear effects. Here, however, it should be noted that in addition to the surface hardness of glass fibers (about 1,400 HV), particular color pigments such as titanium dioxide (about 2,200 HV) can cause a significantly higher wear, because the hardness of hardened mold steels are at about 700 to 900 HV. 

It should be recognized that surface finish can be more than just a cosmetic standard. It also affects product quality, mold or die cost, and delivery time of tools and/or products. The surface can be used not only to enhance clarity for the sake of appearance but to hide surface defects such as sink and parting marks. The Society of Plastics Engi-neers/Society of Plastics Industries standards range from a No. 1 mirror finish to a No. 6 grit blast finish. A mold finish comparison kit consisting of six hardened tool steel pieces and... 

When tool steels of high hardness are used they are supplied in the soft annealed condition (hardened mold inserts for cores, cavities, other molding surfaces and gibs, wedge locks, etc are typically hardened to a... 

Relative tooling cost, single cavity Lowest. Machined aluminum may be variable, depending on quantity required 20 percent more. Hardened-steel tooling 20 percent to 25 percent more. Compression-molding steel tools... 

Sinking (bobbing) n. In mold making, pressing a hardened hob into annealed, soft mold steel or beryllium copper. 

The principal mold steels are the P-type mold steels as specified by the American Iron and Steel Institute, specifically P6, a carburizing steel having moderate hardenability P20, also with moderate hardenability and P21, a deep-hardening steel. 

The most important properties besides uniform structure and freedom from defects in selecting a steel for molds are compressive strength, harden-ability, machinability, stability in hardening, and polishability. In the majority of cases, it is possible to work vdth three basic types of mold steel, namely, AISIP20, AISI H13, and AISI01. 

Despite all the new developments, the long-standing DIN steels still play an important role. Often, in standard applications, depth-hardened or hot work mold steel is sufficient enough, and the cost of brand-name steel would not pay for itself with the application of the mold. The selection of steels should therefore always be considered from two aspects technical feasibility and economic benefits. 

Type Non-alloyed mold steel Corrosion resistant case hardening steel Corrosion resistant heat treated stainless steel Standard case hardening steel Heat treated mold steel... 

Type Heat treated mold steel Standard hot working Highly alloyed chrome Special case hardening Special through hardening... 

Pre-hardened plastic mold steels (hardness -31 HRC) Hardened plastic mold steels (hardness -62 HRC) Case hardening steels (hardness -62 HRC) Surface finished steels (700-3500 HV)... 

The desired plastic forming is mostly carried out under hydraulic presses, to ensure the required material properties. After forming, the steel manufacturer carries out suitable heat treatment, which may be either preliminary heat treatment prior to machining, or final heat treatment in the case of pre-hardened plastic mold steels. 

The transformation behaviour of plastic mold steels are described in time, temperature, transformation (TTT) curves in order to better understand the transformation processes involved in hardening and in austenitizing. 

The pre-hardened plastic mold steel 1.2312 (40CrMnMoS8-6) is not suitable for molds with high surface requirements or mechanical stresses, because of its high sulphur content. In combination with manganese, the sulphur forms long-chain sulfides that can cause the following problems ... 

Pre-hardened plastic mold steels for all standard applications (hardness range... 

Through-hardening plastic mold steels for hardening after (pre-)machining, e.g. for molds and tools subject to high wear (hardness range 44 to 62 HRC)... 

Corrosion-resistant plastic mold steels e.g. for PVC processing, pre-hardened to approximately 30 HRC for standard applications, up to 53 HRC for high levels of wear, with hardening after (pre-)machining... 

Precipitation hardening plastic mold steels for high-wear applications hardness after precipitation hardening 55 HRC... 

---