moulds

Plastic Mold Steel for Mask Machine

2020-06-09
2Cr13, 3Cr13 and 4Cr13 are all belong to plastic mold steels, widely used for mask machines. We recommend you the regular stock of 2-4Cr13 of Ningbo Ningshing Special-Steel, which with the competitive price, welcome to follow us and contact us.


01. The stock list of Ningbo Ningshing Special-Steel

 



02 Introduction of Plastic Mold Steel
 
  1. Plastic mold steel refers to the mold used to produce general-purpose plastic (such as polyethylene, polypropylene) work pieces.
  2. In the plastic part forming molds, the quality requirements of the types of plastic, the production batch, the complexity of the work piece, the accuracy and the surface roughness are the main factors that determine the choice of plastic mold steel.
  3. According to the production process, it can be divided into:
Injection molding (TV shell)
Compression molding (electric switch box)
Extrusion (plastic beverage bottle)
Blow molding (plastic steel doors and windows)
Plastic packaging (electronic chip)
Following are some terminal products of plastic mold steel

 
 


03. Classification of plastic mold steel

With the serialized development of plastic mold steel, there is roughly the same classification in all countries, and can be generally divided into six categories according to their performance and use conditions.
 
Type Typical Grades Main Application
Non-alloy steel S45C~S58C, 45, 50, 55 Small-sized plastic molds with simple shapes, the plastic mold or plastic mold base with low precision requirements, not long service life.
Carlmrizing Steel 20Cr, 12Cr2Ni2, 12CrNi3, 20CrMnTi, 20Cr2Ni4 Plastic mold with low precision requirements
Quenching CrWMn, Cr12MoV, D2, SKD11, 5CrNiMo, 4Cr5MoSiV1, H11, H13, SKT4, SKD61 Pressing thermosetting plastics, molds for composite reinforced plastic products, and plastic molds with large production batches and long service life.
Pre-hardening FS738, FS788, P20, H13, 718 Plastic molds with complicated shapes, large-scale, precise and large production batches.
Hardening 10Ni3MnCuAl, FS816, NAK55, NAK80, 18Ni Plastic molds with complicated, precise, long service life.
Corrosion-proof FS136, 4Cr13, 9Cr18, FS139, FS2010, FS633, Cr17Ni4Cu4Nb Production of plastic products using chemically corrosive plastics as raw materials

 

04. Key properties of plastic mold steel

1.Abrasion resistance
During the use of plastic molds, there will be various types of abrasion due to the direct contact with the materials, which is generally related to the hardness of the mold surface. The higher the hardness, the better the wear resistance. Of course, for different plastic products, the required hardness is also different. In a word, plastic mold steel has good wear resistance and corrosion resistance.

2.Strength
Due to the forming pressure, plastic molds require higher strength. For large plastic mold steel, the synergy between strength and toughness should be considered. If the toughness factor is ignored, it is easy to make the dynamic and fixed molds inseparable and even scrapped when it works.

3.Corrosion resistance
Most of the raw materials of plastic products are organic chemicals, so it will release corrosive gas in the molten state of casting, which has a certain corrosive effect on the surface of the plastic mold cavity that has been polished. Meanwhile the mold is used repeatedly, the corrosion situation will become more and more serious. As a result, etching pits and other patterns will be formed on the surface, which will directly reflected on the plastic products, resulting on a higher defective rate of the products. It is also a waste of mold materials, so it is very necessary to choose corrosion-resistant mold materials to produce plastic products that will release corrosive gases in the molten state.

4.Heat resistance
The temperature of plastic molding is generally between 150-350℃. If the plastic has poor fluidity, it will cause partial heat accumulation in the mold, which will exceed 400℃ in a short time. As a result, it will cause the thermal deformation of the mold and reduce its accuracy. Therefore, a higher heat resistance is required by the plastic mold steel.

5. Cutting Machinability
In order to make the plastic mold have better dimensional accuracy during the cutting process, it is necessary to pay attention to its cutting property. Usually the cutting machinability of the steel is affected by the hardness, inclusions, structure, etc.
 
  1. Polishability
For plastic molds, a smooth cavity surface and the mirror polishability are required by most of them, which ensures that plastic plastic products are easy to demoulding and have an aesthetic appearance. The metallurgical quality, structure, hardness, and polishing technology of plastic molds can affect the mirror surface processability. Plastic mold steel with high mirror surface processing performance generally adopts refining technology, forging with large compression ratio or rolling, so the uneven microstructure of steel is easy to cause defects such as patterns and small pits. Therefore, the casting temperature and tapping temperature of the steel in the casting process are more important. At the same time, a sufficient forging process and high temperature homogenization heat treatment will effectively improve the mirror machinability. During the grinding process of steel, it is easy to increase the surface temperature and cause changes in the structure. Therefore, it is necessary to select the appropriate grinding wheel and grinding fluid. When grinding the surface of the cavity, the grinding direction can be changed frequently.
 
  1. Hardenability
Corrosion-resistant mold steel usually contains a relatively high content of chromium, and the hardenability is relatively high. Besides, after heat treatment, the structure of the surface and core and the hardness distributed evenly, which is suitable for making various types of plastic mold steel.
 
  1. Others
In order to meet the development trend of different shapes of plastic products, plastic mold steel should also have the weldability.

05. Technical index of plastic mold steel


 

Related News