The United States is the first country to list the special steel for plastic mold in tool steel, which is mainly represented by P and divided into five categories.

◆ carburized plastic mold steel: P1, P2, P3, P4, P5, p6. The carbon content of this kind of steel is very low, mainly in the early period of the United States and the extrusion molding method, which requires good cold plasticity and high extrusion performance. After forming, the surface carburization and quenching can improve the surface hardness and long service life. Ultra low carbon in the core can minimize the deformation during quenching.

◆ quenching and tempering plastic mold: P20, p21. The amount of P20 in the plastic mold is very large, it has become the main body, most of which are used in the pre hard state.

◆ medium carbon alloy tool steel is used for thermosetting plastic mold. Steel grades are H13, while L2 and S7, O1 and A2 are also used.

(1) It is basically a secondary hardening steel with good thermal strength at 500-600oc. 02.png

(2) High chromium content, good atmospheric corrosion.

(3) Excellent hardenability, suitable for large modules.

◆ stainless steel is used for plastic mould with high corrosion resistance requirements, and the main steel grades are 420414l and 440416.

◆ aging steel is aged to obtain high performance. There are two kinds, one is p21 low carbon Ni-A1 aging steel, the other is 18Ni martensitic aging steel. The latter is a carbon free, high-purity, high-strength and high toughness material for aerospace industry. It is used in plastic mould with high requirements of mechanical properties, dimensional accuracy, finish and corrosion resistance.

Selection of plastic mould steel

For thin-walled plastic box, when the production batch is less than 100000 pieces, P20 and p21 are used as pre hard state (hb250-300), and 414l is used when the corrosion is strong.

Common plastic mould with high life, P6 or P20, after carburizing and quenching, the hardness is hrc54-58; when the plastic parts are not too large, O1 and S7 can be used. 420 for strong corrosion.

Non high temperature thermosetting mould P6, P20 are used after carburizing and quenching. 420 for corrosiveness.

H13 and S7 or cemented steel P4 for high temperature thermosetting plastic mould. These chromium containing materials have good tempering resistance and high temperature oxidation resistance. Plastic mold steel is divided into five categories: pre hardening ordinary plastic mold steel, pre hardening high quality plastic mold steel, pre hardening high hardness plastic mold steel, pre hardening anti-corrosion mirror plastic mold steel, anti-corrosion mirror plastic mold steel, and quality grade distribution of five categories of plastic mold steel

The mold category is divided into the following categories according to the American spi-spe standard

1、 101 model (spi-spe standard 1000000 beer or above, long-term precision production model)

1. Detailed die structure drawing is required

2. The minimum hardness of die material is 280bn. (DME × 2 steel / 4140 steel)

3. The steel of internal mold with glue position must be as hard as 48 ~ 50HRC. Other parts such as row position, press lock, press strip, etc. shall also be hardware

4. Thimble plate shall have guide post

5. There should be hard disk for row position

6. If necessary, temperature control shall be provided for upper mold, lower mold and row position

7. For all water transport channels, it is recommended to use non electric nickel dipping or 420 stainless steel as formwork, so as to prevent rust and clean up garbage

8. Straight lock or inclined lock is required

2、 102 type mold. (no more than 1000000 beer, mass production mold.

1. Detailed die structure drawing is require。

2. The minimum hardness of die material is 280bhn. (DME × 2 steel / 4140 steel)

3. The steel of internal mold with glue position shall be hard to the minimum 48 ~ 52hrc, and other useful parts shall also be hard to the minimum 48 ~ 52hrc

It should be treated in the same way

4. Straight lock or inclined lock is recommended

5. The following items may or may not be required, depending on the final production quantity. It is recommended to check whether the following items are needed during quotation:

A. Ejector plate guide post

B. Line position hard disk

C. Electroplated water holes

D. Plating die cavity

3、 103 type mold (less than 500000 beer, medium production mold.)

1. Detailed die structure drawing is required

2. The minimum hardness of die material is 165bhn. (DME × 1 steel / 1040 steel)

3. Internal mold steel is P20 (28 ~ 32hrc) or high hardness (36 ~ 38hrc)

4. Other requirements depend on the need

4、 104 models (less than 100000 beers, a small number of production models

1. Die structure drawing is required

2. Die material P20 (28 ~ 32hrc) can be made of mild steel or aluminum (1040 steel)

3. Aluminum, mild steel or other approved metal can be used for internal mold。

4. Other requirements depend on the need

5、 105 models (less than 500 beers, first model or test model)

1. Aluminum cast iron or epoxy resin or any material can be used as long as it has enough strength to produce the minimum number of tests.