The Different Types of Rubber Moulding With Their Pros and Cons

“Moulding” is a procedure used in the manufacturing industry where raw materials, such as plastic, rubber, metal and glass, are altered into different shapes using a mould. A mould is a container into which the raw material is poured when in a liquid state and then turns into a solid. The mould is typically comprised of steel to avoid quick wear-and-tear from multiple uses.

What Is Rubber Moulding?

Rubber moulding is a procedure where a rubber product is created from elastomers, also known as untreated rubber. The elastomer is a natural polymer presenting with elastic properties and will return to its original shape when applying pressure. The elastomer is utilised in various different industries not only because it presents with a malleable characteristic, but also because it can be used in both the correct and domestic sectors.

What Are the Different Types of Rubber Material Available?

There are various types of rubber compounds available and each presents with definitive features alternate to the other. A specific selection process assists with choosing the correct rubber compound. Certain considerations need to be taken into account to ensure that the compound is successful in achieving optimal performance levels. The considerations are below.

  • Sealing the fluid so that the compound can absorb or transmit energy or fluid.
  • The material is measured as cost per part.
  • The location of the part must be identified as inside or outside.
  • The temperature requirements of the material.
  • Any exposure to chemical substances.
  • The physical properties of the compound and regulatory requirements.

What Is the Rubber Moulding Process?

1. Injection Moulding

Injection moulding is a procedure where the heated rubber material or compound is injected into the mould under high pressure. When injected, the material will be in a molten state and is kept inside the barrel of the injection instrument. This is one of the most effective techniques of creating moulded rubber products.

The injection moulding procedure is not as complicated as one may consider, but there are certain steps to be followed which are noted below.

The first step is to place the uncured rubber material or compound into the injection barrel. It will be in the form of a continuous strip making transference into the barrel simple. Once it is fed into the barrel, it is warmed by the auger screw n the temperature-controlled barrel by pulling the auger screw backwards.

When the auger screw is in motion, the rubber material will be injected into the rubber mould containers using the injection press. The auger screw is pushed forward when the mould closes under high pressure; thereby, forcing the material into the cavities or containers. The auger screw will turn once again to refill the barrel when the material is cured in the heated mould and can be removed when the mould is opened.

What Are the Benefits of Injection Moulding?

There are various benefits to injection moulding including:

  • Speedy production of moulds.
  • Minimal wastage of materials.
  • Flexibility in mould design.
  • Reduced labour costs.
  • Flexibility regarding mould colour and materials used.

What Are the Disadvantages of Injection Moulding?

There are different disadvantages to injection mould including:

  • High cost for initial tooling.
  • Difficulty in determining overall costing.
  • Restricted part designs.

2. Compression Moulding

Compression moulding is one of the simpler forms of rubber moulding whereby the rubber material or compound is placed directly into the mould container. By doing this, it can take the shape of the cavity once the mould is closed. Compression moulds differ in shape and size making this type of moulding flexible.

To complete a compression moulding procedure, it is necessary to place the uncured rubber compound or material into the mould which is closed under hydraulic pressure. The pressure will be removed when the mould cavity opens and any excess material will be trimmed from the cavity when the material is placed in the container. Compression moulding is typically completed for compounds with a medium hardness and any flashing is reduced in this procedure.