Industrial Processes and Manufacturing: An Overview

Injection Moulding

• Injection moulding is a manufacturing process for producing parts by injecting molten material into a mould.
• The process involves feeding the polymer granules into a heated barrel, where they melt into a liquid.
• The liquid polymer is then forcibly injected into a mould, where it cools and solidifies to the shape of the mould.
• Injection moulding is used in the mass production of items, including plastic bottles, toys, and car parts.

Extrusion

• Extrusion is a process used to create objects of a fixed cross-sectional profile.
• A material is pushed or drawn through a die of the desired cross-section.
• The two main types of extrusion are hot and cold extrusion.
• Frequently extruded materials include metals, polymers, ceramics, concrete and foodstuffs.
• Extrusion can be continuous, producing theoretically limitless lengths of material, or semi-continuous, producing many pieces.

Blow Moulding

• Blow moulding is a process used to produce hollow plastic parts.
• It involves melting the polymer and then forming it into a preneform or parison.
• Compressed air is then used to 'blow' the preform into the shape of the mould, hence the name blow moulding.
• Blow moulding is commonly used for making single-piece items such as bottles, jars, or containers.

Rotational Moulding

• Rotational moulding, or roto-moulding, involves heating a hollow mould, filled with a powder or liquid resin, on a rotating arm.
• The rotation distributes the polymer, coating the interior of the mould, creating a shell with uniform wall thickness.
• It is a versatile process allowing for a boundless number of shapes and sizes from simple to intricate.
• Suitable for medium to large sized parts and with appropriate design, complex parts can be produced at a low cost.

Compression Moulding

• Compression moulding involves placing a preheated plastic in an open, heated mould cavity.
• The mould is then closed with a top or plug member, pressure is applied to force the material into contact with all mould areas, while heat and pressure are maintained until the moulding material has cured.
• It’s among the oldest materials processing techniques and primarily used with thermoset materials but can be used with certain thermoplastics.

Understanding Additives

• Additives are components added to the basic polymer to change its characteristics or behaviour.
• Some commonly used additives are plasticisers, which increase flexibility, and flame retardants, which reduce flammability.
• Other additives include stabilisers for UV-protection, colour pigments, and anti-static agents.
• Knowledge of which additives to use for a given product or environment can significantly impact the polymer’s performance and lifespan.

Note: Always remember that different processes are used for different applications, and each has their own pros and cons. The type of polymer and the end product characteristics will often determine the most suitable manufacturing process.