Types of Plastic Moulds: The Comprehensive Guide

Plastic moulding is a process that puts the raw or molten plastic material into moulds for designed shapes. Every kind of plastic moulding has different types of plastic moulds, and the moulds choosing is usually decided by moulding temperature, mould material durability, etc.

Custom mold makers generally satisfy their customers’ requirements of shapes with custom plastic moulds which nearly can fit all specially designed parts. For different plastic moulding types, moulding companies provide different types of plastic moulds.

This article will introduce the 6 commonest types of plastic moulds which are utilized in different plastic moulding. With several minutes of reading, you will cognize the differences in plastic moulds clearly.

Types of Plastic Moulds

Moulds for Compression Moulding

What Is Compression Moulding?

Types of plastic moulds of this kind of moulding should be heated. When you pour raw plastic material, this mould compresses it for the desired shape. This moulding way needs a high temperature during the moulding process to ensure good strength in the final product. Finally there has a cooling system for molten material to keep its form before it pulled by ejects.

How Compression Moulds Work?


This one of the types of plastic moulds takes two heat halves. Upper mold half can move and provide certain pressure to ensure the row material molded. Lower mold half is fixed, and designed as customers desired shape. With the pressure of the upper half, plastic materials were molded, and the lower half ensure it can be shaped as designed.

Products of Compression Moulding

Compression moulding fit for molding complex, high-strength fiberglass reinforcements. It is a high-volume, high-pressure method. This one of the types of plastic moulds can mold large, fairly intricate parts. It also is lower cost molding methods than other molding ways. Moreover it wastes relatively little material, taking advantage when dealing with expensive compounds.


Moulds of Extrusion Moulding

What Is Extrusion Moulding?

This kind of moulding is usually used to produce long continuous shapes such as a pipe. It takes “die” instead of “mold”. The operator put the plastic material into plastic powder, then the plastic material is heated and squeeze through custom die.

This moulding process relatively needless cost than other moulding because of its simplicity of the die and operation of moulding machine.

How Extrusion Moulds Work?

As one of types of plastic moulds, it also can be called steel die. It is a custom plastic mold (mould), designed as customers’ requirements. Plastic materials enter by powder, motor rotates the material into heat area. Then plastic material is melted, squeezed, and shaped out of steel die.

Products of Extrusion Moulding

Extrusion moulding produces plastic parts that have a fixed cross-sectional profile, such as straws, hoses, and PVC piping. As the limitation of the extrusion moulding process, products that can take the moulding way are very narrow.


Moulds of Blow Moulding

What Is Blow Moulding?

Blow moulding heats plastic and blows them into a custom mould cavity, then it creates a hollow object. It is usually used to create hollow containers such as bottles. This types of plasitc moulds are designed as a huge bottle to ensure that it can mold other huge objects. There are three steps of blow moulding, first heat plastic to create a parisoon. Then put the plastic parison into the mould and ensure it on the top of the mould. Finally air blows dawn onto the plastic parison and make it across the interior walls of the mould cavity.

How Blow Moulds Work?

Products of Blow Moulding

Blow moulding is usually used in the manufacturing industry to make a hollow objects of plastic or glass. Bottles or round containers are common products which made by these types of plastic moulds. Custom plastic mold (mould) can help moulding objects formed as designed.


Moulds of Injection Moulding

What Is Injection Moulding?

With the wide range of use and simple operation of the injection molding machines, plastic injection molding is one of the most common moulding methods in the manufacturing industry. Plastic injection moulding manufacturers put the material into the hopper, and the heating cylinder makes the plastic become molten. Through runner the molten material arrives parts cavities, after cooling, a plastic injection part is finished.

How Injection Moulds Work?


Every injection molding machine was composed of two parts: “A” plate and “B” plate. Two parts make a whole injection mold. Therefore we called “A” plate “A” half, “B” plate “B” half.

“B” half usually named life half, because it is moving section, and “A” half normally called dead half because it does not contain any moving section. Every part was made in mold cavities. The line that two halves jointed is called parting line. When molten material was injected into the mold, sprue puller provides a power against the impact force of injection to balance them and ensure that mold has no defects. The ejector pin is used to push finished molds, while the return pin is used to push the ejector pin back.

Products of Injection Moulds

Injection mold makers provide different mould to produce different parts. Nowadays injection mold makers can make injection mold services for their customers in various industries. This one of the types of plastic moulds is used to create wire spools, packaging, bottle caps, automotive parts and components, toys, pocket combs, some musical instruments and parts of them, one-piece chairs, and small tables, mechanical parts, etc.


Moulds of Rotational Moulding

What Is Rotational Moulding?

This kind of moulding also called rotomolding. As one of the manufacturing processes it can mould large hollow parts. Pour the row plastic material, heating it, and rotating the molten material over the mould. When it cooling, there are finished rotational moulded parts.

As its unique moulding process, rotational moulding is usually used in large parts production.

How Rotation Moulds Work?


Rotational moulding has a heated hollow mould which is filled with a charge or shot weight of the material. Then the mould slowly rotates, making the softened material to disperse and stick to the walls of the mold. To keep thickness throughout the part, the mould need to rotate at all times during the heating phase in order to avoid sagging or deformation also during the cooling phase.

Products of Rotational Moulding

Rotational moulding is usually used to mould large hollow products, such as bulk containers, storage tanks, marine buoys, pet houses, car parts, road cones, recycling bins, etc.


Moulds of Thermoforming

What Is Thermoforming?

Thermoforming can be seen as a simple vacuum forming. Plastic sheets are heated to a pliable forming temperature, moulded to the custom shape in a mould, and trimmed to create a usable product. When the products need thinner walls and certain material types, the material should be heated in a high-enough temperature that permits it to be stretched into or onto a mould and cooled to a finished shape

How Thermoforming Moulds Work?


Thermoforming usually has three process.

  1. The plastic sheet is heated
  2. The sheet is formed to the custom shape in a mould
  3. The shapes are trimmed

Products of Thermoforming

Thermoforming is widely used in production of disposable cups, containers, lids, blisters and trays, etc. Generally speaking, it needs about 8 weeks to get thermoforming moulds ready for production. It is suitable for mass production. The more products it moulds, the less cost it needs.



In moulding industry, which also called molding industry in the USA, no matter what kind of molding you take, mold is an important part of your molding process. It is designed by customers unique requirement, and determine the shape even quality of molded parts. For example, at the injection molding process, if you have even a very little mistake in mold design, it may cost you a lot to correct the error. Unsuitable mold design can also cause molding defects.

Different types of plastic moulds fit with different moulding. For example, extrusion moulding needs has a custom die as one of the types of plastic moulds. Compression moulding requires its moulds more powerful to mould objects. This types of plastic moulds need high-pressure resistance.

Injection mold makers in China still trying to provide advanced injection mold services and all types of plastic moulds for their customers. Custom molds in China need to be tested many times for their real product parameter. And in China, injection mold manufacturing has complete a comprehensive service system in the world. No matter where you are, we can provide our injection mold as well.

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