Mold steel is divided into three type according it’s servicing condition in America,Tool Committee Of AmericanMetal Association list three types of the steel,there are Cold-Worked Steel,Hot-worked steel and Plastic Steel.Hot –worked steel is divided into 12 types ,Cold-worked Steel is divided into 9 type,Plastic mold is divided into 2 types,the material of each type are depend on three main factor:

The complexity of the size and form

Material be manufactured

Requiements of durability and life span

Classification of the  Cold-worked steel

Classified 5 types :W group、O group、A group、D  group、S group

W group that is water steel which have 11tyoes,7 Carbon Steel and it’s i carbon including range from0.7%-to.3%.

O group that is Oil steel which have 4 types ,include Carbon range from  0.85 to 1.55%.

 A group that is alloy cold-worked  steel which have 9 types and it’s i carbon including range from  0.5 to 2.25%.

D group that is High carbon and chromium Cold-worked steel which have 7 types and it’s i carbon including range from 0.9% to 2.5%.

S group that is clash Resistant steel which have 7 types and it’s carbon including reange from 0.4 to 0.6%.

HSS group also included in Cold-worked steel , SHSS group ,HA group),Powerd steel,PIM group) ,F group, Lgroup.

The opital of Cold-worked steel

The main seriese of the Cold-worked steel is Hight hardness Cold-worked steel,it is used in mold which resistant press and polish,it hardness more than HRC60-62..Hardness less that HRC60-62 is adopt s group and part of A group and the general steel, spring steel,Hot-work mold or base steel ,About the Stamp such as the auto parts stamp ,it adopt the casting iron .about the simple and shot life spam usually adopt the high polymer clad material .

High Speed Steel and Super High Speed steel is increasing in the Cold-worked steel ,it is especial for the comperative value of the anti-press and hardness and it’s hardness can be choose betweem HRC60-70 .

The powerd steel have advantage in polishness  resistant and it’s hardness less than HRC60-62,for this advantage it should be used more.

Carbon Tool Steel are still have some room in the clash mold whose life span is 10 Million.

The classification of the Hot-worked steel

Hot-worked steel is divided into two kinds in America,there are Hot-worked mold steel and Super hot Alloy.

The optial of the Hot-worked steel  

 Hot-worked steel for it’s work condition ,the material should with the strong hot and polishness resistant ,To reach the life span of the mold ,mold need be cold ,change between the hot and cold condition ,mold will have breakness ,so the material should have the quality of the anti-breaking texture and anti-hot .

To choose the material according to the Hot-Strong:

Low alloy mold steel (6G,6F2,6F3)-Middle chromium Hot-worked mold steel (H11、H12、H13)- tungsten Hot-mold mold steel (H21、H22).

No-standarda Hot-worked mold steel ,such as hot upset forging mold use the time hard 6H4.When use H11、H12、H13,it can’t satisfy with the Hot polishness resistance ,so we can choose 6H1、6H2.

When we requist the mold with the main quality of the hoo-worked polishness resistance ,we can chosse D2、D4--M2、M4—Powerd steel.The steel of the alloy and cobalt alloy have quality of the anit-high temperature,But for it’s disadvantage of the anti-hot and anti-cold,so it can’t undergo the condition of the Hot and Cold

The classification of the plastic mold steel

America is the earlist country list the plastic mold steel ,show it with P.i can be divided into 5 types.

Case-Hardened Steel:P1,P2,P3,P4,P5,P6.,this kind of steel include litter carbon,it requist perfect cooling and good press ,after prototype the surface of the hardness shoul be very high,the life span shoud be long.

Plastic mold steel:P20,P21.At present the usage of the P20is large and be the main material ,most of them are used under the condition of Pre-hardness ,.

Middle carbon alloy used in hot-fixed plastic mold steel,steel No.H13, the L12 , S7,O1and A2 also are used in this kind of situation .

1、Belong to the second tiem harden steel,between 500-600℃,it’s hot-strong is perfect.

2、Include high chromiumand have a good anti-air resistance.

3、Fit for larg mold for it’s good hardenability.

Stainless steel use in the mold with requiement of the corrosion resistance,The main Steel No. are 420,414L,440,416.

Time efficence steel with a perfect usage undergo the deal with the time efficence,There are two kinds ,one is P21,Low carbon Ni-A1(Tiem efficence steel);the other is 18Ni,The last one used in High purity ,High strong ,High toughness material in Space industry and used in mold with mechanical property.size accurity ,clearness and corrosion resistance.

The optical of the Plstic mold

The plastic box with thin-wall , when the production on a batch basisless than 10 million peacies ,we should use the P20、P21, HB250-300,when the corrosion resistance is strong we should use 414L.

The general plastic mold steel should use P6 orP20, The hardness should be HRC54-58 after undgoing the Case-Hardened;When the plastic parts is not very large we can use O1、S7. when the corrosion resistance is strong we should use 420.

No high temperature mold ,we shoul use P6、P20,the corrosion resistance should use 420 after the Case-Hardened.  
high temperature mold use H13and S7 or Case-Hardened steel P4,Those include high . chromium and with the perfect anti-oxidability.