Plastics - EduqasScales of production

There are four terms used to describe the scale of production in relation to manufacturing a product:

• prototype and one-off production
• batch production
• mass production
• continuous production

Prototypes and one-off production

There are many ways to produce a prototype - some are rough and look like models and others are well finished and function as intended. It is now possible to 3D print many different polymers. Engineering companies have welcomed this technology as 3D printing is classed as additive manufacture, rather than subtractive. Additive manufacture builds up the polymer form in layers, whereas subtractive manufacture takes material away from a larger piece. There is very little waste when using additive techniques, making it more environmentally friendly.

There are many 3D printer filaments to choose from - some polymer-based filaments contain carbon fibre, different wood fibres and even metals. It is possible to make a functioning prototype with these technical filaments.

A custom-made or bespoke product that is made from a polymer could be made to a customer design specification, eg acrylic signs on shops.

Batch production

Batch production is where many items of the same product are produced, such as an acrylic menu stand for use in a chain of restaurants.

It is likely that the acrylic stand would be laser cut, heated on a line bender and then left to cool in a cooling jig. The jig ensures that each menu stand cools and remains in place at the same angle each time.

When a product is made in a batch, it is often far cheaper per product than when making just one. A sheet of acrylic can be bought in many different sizes - for example, if the sheet is 1000 mm × 600 mm, it can fit inside many larger laser cutters and many parts can be cut from it while it is in the machine.

Example

Assume the cost of a 1,000 mm × 600 mm sheet of acrylic is £8.00.

Therefore, one menu not made as part of a batch = £8.00

If each menu stand uses a 200 mm × 300 mm sheet of acrylic:

1,000 ÷ 200 = 5

600 ÷ 300 = 2

5 × 2 = 10

Therefore, 10 menu stands can be cut from the sheet of acrylic.

Batch of ten menu stands = 8 ÷ 10

= 0.8

One menu = 80p (in batch)

Mass production

Mass-produced products are manufactured in large volumes, and are often made by automated machinery with assembly line workers used to fit parts together or to add standard components, such as screws and hinges. An example of mass production for polymers is blister packs that contain tablets. In this case the whole process would be automated and workers may only be used to check the product or pack it into shipping boxes.

Continuous production

Continuous production takes place 24 hours a day, 7 days a week and, in some cases, 365 days a year. When products are made from a polymer using continuous production methods, injection moulding is likely to be the method used to form the plastic. Children’s building blocks are injection moulded in factories that utilise automation - not many people are involved in the manufacture as robots and machines do most of the work.