Injection moulding vs vacuum forming

Plastics are used throughout a variety of industries, providing strength and versatility across a range of applications from human body parts to automotive uses. Every application requires a certain manufacturing process that is able to mould the plastic to the specifications required. The two most common processes are injection moulding and thermoforming.

Thermoforming

Commonly used for larger-scale designs involving shorter production runs, thermoforming, also known as vacuum forming, is a process that involves moulding a heated sheet of plastic to the surface of a female or male mould. As the plastic is heated, it bends to take the form of the mould, which it keeps once cooled as described in http://www.bpf.co.uk/plastipedia/processes/vacuum_forming.aspx. This differs from injection moulding as only one side of the plastic is affected by the mould. Typical applications include things such as shower trays and baths, boat hulls, sandwich boxes and yoghurt pots.

Advantages include:

– Lower startup costs
– Extreme adaptability and easy adjustment
– Quick product development and rapid prototyping
– Great for jobs that need to be repeated. Aluminium casting is often used, which has an unlimited lifespan
– As https://www.bridgewooduk.com/production-assembly/vacuum-forming will also tell you, thermoforming offers a wide choice and flexibility on colour, finish and material selection

Disadvantages include:

– Achieving a deep thickness can be challenging
– Creating intricate parts can be difficult, although details can be added later through pressure forming
– The cost per piece is often higher, which makes thermoforming less competitive than other methods where larger quantities are produced
– Finishing costs are often higher, and the process is labour intensive

Injection Moulding

A much more complex process, injection moulding requires a detailed tooling or mould before the process begins. Normally crafted from aluminium or stainless steel, split-die moulds are filled with melted liquid polymers at high temperatures and under extreme pressures. Once the moulds have cooled, they are opened and the formed plastic is then released. Applications include toys, combs, certain musical instruments, small tables and most plastic products available today.

Advantages include:

– Low scrap rates due to efficient use of material
– Efficient for producing large quantities of small parts
– Automation can be used
– Lower cost per unit than thermoforming
– Parts normally look very finished

Disadvantages:

– Higher costs up front
– Takes longer to manufacture due to the need for a precise mould
– Engineering expertise is required to create mould