Injection moulding plastic parts for consumer electronics

The global consumer electronics industry is one of the largest consumers of components manufactured from plastics.

Plastic manufacturers produce parts for every gadget, computer, printer or camera. These require plastic housings, lighting housings and cases, light fittings and switches, and circuit board mountings and wiring to function. The majority of these items can be made via the injection moulding machine, or through another moulding process.

Versatile plastics find favour

Plastics fall into two broad categories:

• thermoplastics such as polyethylene, which can be repeatedly melted down and re-moulded
• thermosets such as urea formaldehyde, which once set cannot be remelted making them suitable for applications where heat is encountered.

Plastic materials for consumer electronics must have technical and aesthetic attributes. For example, they may need to guard against radio frequency interference and be flame retardant, while also providing soft touch characteristics and scratch resistance.

Consumers expect the latest electronic devices to be rugged enough to withstand being dropped and exposed to moisture. Plastics are finding increasing favour because of their light weight, durability, and low cost, and will continue to replace metal, and perhaps even glass, in consumer electronics manufacturing.

Commonly used plastics in electronics manufacturing include ABS, polycarbonate, and polyamide, all thermoplastics. They have differing qualities in terms of wear and impact resistance, toughness, electrical insulation, and resistance to sunlight, temperature and corrosion. Some manufacturers produce anti-bacterial plastics for medical electronics applications that provide protection against bacteria, viruses and fungi. Biodegradable plastics are also on the market.

"We will try and improve the consistency of the part and process and the longevity of the tool itself.”

Essentra Components and electronics

Essentra Components has two key processes for producing the small components vital to the electronics manufacturing sector. These processes are injection moulding and dip moulding. Essentra uses thermoplastics rather than thermoset materials. Its smallest injection moulding machine has a 15-tonne capacity and machines go up to a 120-tonne capacity. The company offers a wide range of standard parts produced on these machines for multiple industries, including caps, plugs, grommets, inserts, hand wheels, feet, and suction pads, as well as electronics-specific components such as printed circuit board supports, spacers and cable ties.

Eighty-five per cent of the parts produced via the injection moulding process are standard parts, with the remaining 15 per cent custom moulded. If a customer wants a custom mould, they can make an enquiry via Essentra’s custom solutions team. The idea will be sense checked, and if it can be taken forward, will then be assessed by a special cross-functional team including commercial, production and engineering functions.

The tooling drawing and design will also be assessed by the same team of Essentra experts, and modifications and improvements fed back to the toolmaker. Tools will be machined in materials appropriate to the plastic being processed.

“We will try and improve the consistency of the part and process, and the longevity of the tool itself.” Chris Butler, Divisional Engineering Manager at Essentra Components explains, “We mould a lot of polyvinyl chloride on site, so stainless steel tooling must be used. If we were just making a standard part we would use P20 steel and harden the cavity inserts. It depends on the type of material, and the design of the tool.”

Aluminium may be used for ease of machining and for manufacturing prototypes, but it has issues in terms of its softness as a tooling material.

Many millions of parts may be produced from a single injection mould machine tool. For example, one tool at Essentra produces about 4.5 million easy plugs, a protection part, each year.

The consumer electronics market

Essentra provides small but crucial components for consumer appliances, consumer electronics and office machinery and equipment. These include silicone grommets that can withstand high temperatures, touch control spacers for induction hobs, barbed fasteners, cable grommets that work at temperatures of up to 80ºC, arrow head cable ties that can accommodate bundles before or after mounting, and heat resistant snap rivets that can withstand temperatures of up to 130ºC. 

Future innovations in the use of plastics in electronics will include employing smart polymers that change shape in response to light, temperature, humidity, and other environmental factors. Bio-based plastics, based on resins from plants, will also find applications in telecommunications and electronics.