PLASTIC INJECTION MOULDING

Injection molding is the most commonly used manufacturing process for the fabrication of plastic parts. A wide variety of products are manufactured using injection molding, which vary greatly in their size, complexity, and application. The injection molding process requires the use of an injection molding machine, raw plastic material, and a mold. The plastic is melted in the injection molding machine and then injected into the mold, where it cools and solidifies into the final part.

MATERIAL USED IN INJECTION MOULDING

Most thermoplastics can be processed by Injection Moulding. some of the commonly used materials:

• Acrylonitrile-Butadiene-Styrene ABS

• Nylon PA

• Polycarbonate PC

• Polypropylene PP

• Polystyrene GPPS

How Does Injection Moulding Work?

• Material granules for the part is fed via a hopper into a heated barrel, melted using heater bands and the frictional action of a reciprocating screw barrel. The plastic is then injection through a nozzle into a mould cavity where it cools and hardens to the configuration of the cavity. The mould tool is mounted on a moveable platen – when the part has solidified, the platen opens and the part is ejected out using ejector pins.

• After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould maker (or toolmaker) from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part Parts to be injection molded must be very carefully designed to facilitate the moulding process; the material used for the part, the desired shape and features of the part, the material of the mould, and the properties of the moulding machine must all be taken into account. The versatility of injection moulding is facilitated by this breadth of design considerations and possibilities.

Fig:Injection moulding machine

Types of Injection moulding machine:

Performance Requirements Practical Approach Engineering Approach Material Selection Cost/Performance Properties Process Ideal Choice

1. Hand injection moulding

2. Semi-auto (Plunger type) Injection moulding

3. Fully-auto (Screw type) Injection moulding

4. Advanced injection moulding

Plastic injection molding applications

• Automotive components

• Avionics components

• Cable assemblies

• Computer electronics

• Electronics components

• Engineering prototypes

• Instrumentation

• Marketing samples

• Material quality testing

• Medical & dental products

• Model shops, toys, hobby