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Insert Moulding

What is Insert Moulding?

Insert moulding is the process by which metals are moulded with plastic components to form a single moulded part.

It is where thermoplastic material is moulded around an insert to produce a moulded part which contains several components.

The insert is placed into the mould for the injected plastic to flow around it.

Insert Moulded Plastic Component

The use of moulded-in inserts offsets the need for secondary insert installation. This can be more cost-effective than putting inserts into a plastic part after it has been moulded.

There are several factors which need to be considered if the process is to be successful.

The degree of shrinkage must be calculated to ensure that the insert and the polymer fit together correctly.

The inserts will have to be the right type of material for the job to withstand the high temperature reached during the process.

Adding the Inserts

Inserts can be incorporated into the component at two different stages: either during the moulding process, or after the moulding process has been completed.

If inserts are incorporated during moulding, this operation will either be completed with the aid of a robot, or by a machine operator.

If the inserts are applied as a post-moulding operation, there may be fewer faulty components than if applied in the moulding machine, where the inserts might dislodge or break.

However, it is important to note that the manual post-moulding process will probably be more time consuming and will require dedicated human labour.

Threaded Insert on Moulded Part

Different Types of Inserts

There are many different types of inserts that can be moulded into a range of different plastic components. Choosing the right materials for the process is crucial, in order to ensure that the final moulded part is functional, durable and aesthetically well presented.

It is worth remembering that the key reason for using insert moulding is to build added strength into moulded plastic components. It is important to pick the correct type of threaded insert to achieve the optimum amount of strength and functionality required for the particular component in question.

These many different types of inserts include magnets, screws, pins, bushings, studs, contacts, journal bearings, tubes, spring contacts and threaded fasteners.

Benefits of Insert Moulding

Design flexibility: insert moulding allows designers to create whatever shape they desire.

Reduced assembly and resource costs: insert moulding combines several elements in one process, making the overall cost less. In addition, the time taken to produce the finished component is reduced.

Increased component durability: the insert is firmly held in plastic before cooling and setting, resulting in increased resistance.

Used with a variety of materials: thermoplastics are often employed, but many different types of plastic resins can be utilised.

Less post-moulding operations: this makes the process more efficient, allowing for ease of assembly while minimising labour costs. The seamlessness of the operation makes it ideal for large scale production.

Reduced size and weight of final component: because the inserts are integrated into the part, there is no requirement for fasteners or connectors.

It is a single, integrated process which can all be done under one roof without the customer having to go the trouble of outsourcing the insert moulding process to a separate supplier.

Applications for Insert Moulding

Insert moulding is commonly used in many different industries, but it is often utilised in the medical, automotive, consumer products and electronics components sectors.

In its most common application, insert moulding is used to add one or more threaded metal inserts into a plastic component. This is necessary when the plastic does not have sufficient mechanical properties, or if additional strength and security is needed for a part.

Examples of Insert Moulded Components

Typical devices and equipment which benefit from the incorporation of inserts into plastic components include:

  • Electrical appliances, such as knobs for appliances
  • Electronic devices, such as power drills and plugs
  • Military equipment, such as portable radios
  • Medical parts, such as camera equipment, cables, and wiring
  • Automotive components, such as electrical sensors, gears, and pedals

If you would like more information on insert moulding, or if you have a particular project which may require inserts, please contact us by emailing or by calling 0121 550 5868.

Insert Moulded Component
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