Steel that Manufacturing Companies use for Plastic Injection Mould


The plastic manufacturing industry is a vital part of the manufacturing industry. The plastic injection moulds, which help create the products, need some special care. In order to shape various products for practical use and also to resist the stress that mass production involves, it is important that the moulds are made from sturdy materials. This is why a number of new-age manufacturers are choosing steel over other materials to make the mould. However, different products need different types of steel to make the moulds. Here are the pointers to get you some idea.


The 5 Classes


Experts in metallurgy divide plastic injection moulds into 5 different classes. They include:


  • Classes 1 and 2


These varieties of plastic mould need mould steel, which has properties to get hardened for better durability. Otherwise, these moulds might crack when treated at extremely high temperatures while manufacturing.


  • Class 3


This Class needs pre-hardened moulds. This makes class 3 moulds sufficiently durable enough to stay hard even during the most rigorous manufacturing procedures. It is more popular in applications that require general-purpose moulds.


  • Classes 4 and 5


Both classes 4 and 5 utilize standard-quality steel for general applications. Mainly, it helps create cavities in the base of moulds. Some are helpful in forming low-requirement and low-cost moulds. Hence, they are easy to maintain and replace.


H-13 steel for Classes 1 and 2


This air-hardening steel is useful for making die-cast moulds.  Such moulds are durable and resistant to high temperatures. Some engineers also choose steel to create cavities on the plastic mould.


420 Stainless Steel for Classes 1 and 2


This variety also offers good resistance to wear and corrosion. This makes it ideal for manufacturing very durable plastic varieties which can withstand very high temperatures. This steel quality is used in manufacturing plastic moulds and parts for industries like electronics, food processing, and medical products.


S136H for Class 3


This steel type is resistant to very acidic substances. It is also a fitting choice for places with humid environments. So it can work for you if you live in hot and humid tropical areas. Its high corrosion resistance, along with durability, makes it perfect for manufacturing different types of plastic products. This includes camera parts, disposable utensils, sunglasses, and various kinds of laboratory equipment. Quite akin to the 420 stainless steel variety, this steel is a good choice for the food and medical industry or in any manufacturing where resistance and temperature application to chemical elements are important.


718H for Class 3


Many leading Plastic Mould Steel Suppliers like TGKSSL recommend this variety to clients who need high-quality yet cost-effective basic moulds within a short time. This steel is, however, not the best choice for making moulds with intricate designs.


P-20 for Classes 4 and 5


One of the most used steels in plastic injection moulds, this general-purpose variety is also used for rubber compression moulds, transfer moulds, prototype moulds, transfer moulds, and holder blocks. The pre-hardened steel is sturdy enough for heavy-duty usage.


Choosing what's best for you


Unless you have been working with metals for many years, it can be difficult to choose the right quantity of steel for your project. This is why you need to get help from a seasoned manufacturer and supplier to make the most of your investment.