Scales of Production
GCSE — 2.1.2 In-depth Knowledge: Product Design
Scales of production
One-off production
Single products made as prototypes, concepts or bespoke custom-made items.
| Advantage | Disadvantage |
|---|---|
| The user will have an original product unlike any other | Lots of manual labour — no production line set up for one product |
Batch production
Products made in limited numbers at any one time, although this may be repeated.
| Advantage | Disadvantage |
|---|---|
| Small numbers of similar items made at one time to satisfy demand | There may be a delay until the next batch is produced |
Mass production
Identical products made in large volume (normally thousands), with automated machinery for accuracy, efficiency and identical outcomes.
| Advantage | Disadvantage |
|---|---|
| More profit — materials bought in bulk, automated machinery needs fewer workers | Initial set-up costs are high; not much flexibility once production line is set up |
Continuous flow production
Identical products constantly being produced 24 hours a day, 7 days a week, with heavily automated production lines.
| Advantage | Disadvantage |
|---|---|
| Huge numbers produced identically, efficiently and quickly — saving time, energy and labour | One single fault can stop the entire production process and be very costly |
Products suited to high-volume, continuous production include drinks cans, plastic bottles, bottle caps, screws and fixings, newspapers and food packaging.
Jigs and repeating activities
Manufacturers use devices to ensure accuracy and consistency when repeating processes:
- Jig — a device used to hold or secure material and guide cutting or drilling tools to ensure accuracy and repeatability
- Pattern — a shape attached to the surface of the material to help shape it
- Template — a tool for marking out a shape repeatedly so it is exactly the same each time
Computer aided manufacture (CAM)
CAM machines are controlled by a computer and offer many benefits:
- Faster than working by hand
- Far more accurate and precise than manual workers
- Repeat tasks consistently and identically
- Support production by making difficult components while others are produced simultaneously
- Produce multiple items in one go
- Save material and reduce waste
- Work without supervision
Producing products using polymers
| Process | Description |
|---|---|
| Injection moulding | Molten polymer is forced under high pressure into a closed mould — used for high-volume, complex products (see below) |
| Blow moulding | A soft plastic tube is inflated to fill a cavity — used for forming bottles |
| Vacuum forming | A sheet of HIPS or acrylic is heated then pulled over a mould by extracting air using a vacuum |
| Press moulding | Polymer sheets are heated, placed over a mould and pressed down to take the shape |
| Compression moulding | Polymer placed into a heated mould cavity, mould closed with a plug and compressed with a hydraulic press |
Injection moulding
Injection moulding is used to make high-volume, often complex, thermoforming polymer products.
- Polymer granules are fed from a hopper into a heated barrel.
- A rotating screw carries the granules forward; heaters melt the polymer.
- The screw acts as a ram, forcing the molten polymer under high pressure into a closed, cooled mould.
- The polymer is held under pressure while it cools and solidifies.
- The mould opens and ejector pins push the product out. The cycle then repeats.
| Advantages | Disadvantages |
|---|---|
| Very fast cycle times, ideal for high-volume production | Moulds are very expensive, so it is only economical in large quantities |
| Complex 3D shapes with holes, ribs, bosses and clips in one piece | Design changes mean making a new mould |
| Identical, accurate products every time | Wall thickness must be fairly even to avoid sink marks |
| Self-finishing — texture or gloss comes from the mould | Draft angles are needed so the product can be released |
| Little waste — sprues and runners can be reground and reused |
Typical materials: ABS, polypropylene, HDPE, polycarbonate, nylon.
Typical products: bottle tops, phone cases, LEGO bricks, chair shells, electrical casings, washing-up bowls.
How to spot an injection-moulded product: small circular ejector pin marks, a sprue mark where the polymer entered, tapered sides (draft angles) and strengthening ribs inside.
Producing products in papers, cards and boards
| Process | Description |
|---|---|
| Pre-press printing | Creates a print layout; transforms electronic files onto paper |
| On-press printing | A plate is covered in ink; paper is pressed against the plate then released |
| Die cutting | Metal cutters stamp out the desired shape from the material (like cookie cutters) |
| UV varnishing | Ultraviolet varnish creates a vivid, luxurious or tactile finish on parts of a design |
| Embossing | Stamping a feature into card/paper to raise it above the surface |
| Debossing | Same as embossing but the feature is below the surface |
| Laminating | Adding layers to card or board to protect items packaged inside |
Books, leaflets and magazines can be printed and bound in different ways. Leaflets can be printed and folded into a smaller form. Booklets are several pages bound, bonded or stitched together.
Offset lithography
Offset lithography is the main commercial printing process for high-volume products such as magazines, books, leaflets and packaging. It works because oil and water do not mix: the image area on the printing plate attracts oil-based ink, and the non-image area attracts water. The image is transferred (“offset”) from the plate to a rubber blanket roller, then onto the paper. Colour images are built up from four inks — CMYK (cyan, magenta, yellow and key/black).
- Advantages: high-quality images, low cost per item for long runs, fast.
- Disadvantages: expensive and slow to set up (plates must be made), so not cost-effective for small quantities. Digital printing is used for short runs instead.