Plastic Production Scales, Jigs and CAM

Choosing how many plastic products to make

A manufacturer needs to match the scale of production to demand: how many products customers are likely to buy. A single experimental plastic casing needs a different approach from packaging required in enormous quantities every day. Customisation, equipment costs and the need for identical parts also influence the choice.

The material alone does not determine the scale. Plastic products can be made individually, in batches or on highly automated lines. The most suitable approach balances the benefits of the required output against the cost and inflexibility of setting up production.

One-off production: a single product for a particular purpose

One-off production means making a single product. It suits prototypes, which allow a design to be tested before committing to manufacture, and bespoke products made for an individual customer.

For example, a designer might 3D-print one plastic controller casing to check its shape, fit and assembly. An acrylic display model could also be made as a one-off. These approaches allow changes without first investing in expensive production moulds.

The main advantage is freedom to create an original product suited to a particular need. However, making and finishing it may require considerable individual attention and manual labour. The time and preparation costs are borne by that one item, rather than shared across many products. A dedicated production line would normally be uneconomical for a single product.

Batch production: limited quantities with repeatable results

Batch production means making a limited number of products at one time. The batch can be repeated when more are needed, or the equipment can be prepared for a different design or colour.

Plastic examples include custom trays, specialist protective covers and small production runs of electronics enclosures. Batch production meets smaller levels of demand without committing to a permanently running line. It also allows a manufacturer to offer variations between batches.

A disadvantage is that customers may have to wait until the next batch is produced. Changing between batches also requires preparation, such as changing a mould or loading a different digital file.

Even a small batch needs consistency. If enclosure lids and bases vary in size, they may not fit together. Repeatedly measuring and marking every component individually takes time and creates opportunities for error. Reusable devices help the manufacturer repeat the same operation accurately.

Jigs and other devices control repeated tasks

A jig holds or secures material and guides a cutting or drilling tool. Suppose a batch of plastic panels needs two holes in the same positions. Each panel can be located in the same jig, and its guides direct the drill to those positions. This avoids separately marking out every panel and makes the hole spacing repeatable.

The panel and jig must be secured before drilling; fingers should be kept away from the drill and appropriate eye protection worn. The drill must stop before the panel is removed or replaced. The operation is complete when both holes have been made, and checking their positions confirms that the setup is producing the required result.

Other devices control different parts of manufacture:

• A template is drawn around to mark the same outline repeatedly. Arranging outlines closely on plastic sheet can also reduce offcuts.
• A former gives material a consistent shape during bending or shaping.
• A pattern reproduces an object’s shape so that a mould cavity can be made for casting.
• A has a cavity that gives the material its shape. Reusing it helps produce matching components.

These devices improve consistency, but their initial setup must be correct: an incorrectly positioned guide can repeat the same error throughout a batch.

High-volume manufacture: mass production and continuous flow

Mass production makes large quantities of identical products, often thousands or more, using automated machinery. Plastic bottle tops, food containers, chairs and toy components are suitable examples where demand justifies repeated manufacture.

High output allows setup costs to be spread across many items. Buying materials in bulk and reducing the manual work needed per item can lower unit costs and improve profitability. Automated repetition also supports consistent dimensions and efficient production.

The disadvantages are high initial equipment and tooling costs and limited flexibility once a line is established. A line designed for one product may be costly to adapt. If demand is too low, the savings per item may not justify the investment.

Continuous flow production is intended to run 24 hours a day, seven days a week. It relies heavily on automation for speed, accuracy and quality control. Mass production describes the quantity made; continuous flow describes how production operates.

Plastic products suited to sustained high-volume production include PVC pipe, cable insulation, polymer sheet, cling film and 3D-printer filament. These can be produced as continuous lengths or films, then cut to length or wound onto rolls. Continuous flow is not restricted to unbroken products: a line making separate identical items can also operate around the clock where demand supports it.

The advantages are rapid, efficient output of huge quantities with less manual labour per item. However, a single fault can stop the whole linked production process, making downtime very costly. Reliable equipment and a steady supply of material are therefore important.

CAM makes repeated manufacture practical

Computer-aided manufacture (CAM) uses computer-controlled machinery to make products or components. Computer-aided design (CAD) creates the design digitally; CAM controls its manufacture. For example, an acrylic component can be drawn using CAD, then its cutting instructions transferred to a laser cutter. CNC routers, CNC milling machines and 3D printers are other examples of computer-controlled manufacturing equipment.

In high-volume plastic manufacture, computer control allows machinery to repeat the same operation consistently. This supports accurate dimensions, matching parts and faster output than making each component by hand. Complex components can be made while other operations take place elsewhere on the line. Multiple items can be produced together, and efficient arrangements on sheet material can reduce waste.

Machines do not need lunch breaks and can sustain repeated work for long periods. This does not remove the need for safe operation, checking and maintenance. CAM equipment is expensive to set up and maintain, and a fault can interrupt production.

CAM therefore becomes particularly valuable when many identical products are needed: its speed and repeatability can justify the initial investment. For a single product, a simpler method may be more economical, although CAM can still be useful for making a complex prototype.