Materials & manufacture · Higher
Manufacturing features
6 cards · 4 quiz · 2 exam
Design & Manufacture · Higher · mrkellydt.co.uk
What you're learning in this topic
Learning intention WALT
We are learning about manufacturing features, specifically to:
know
- flashing, ejector marks, draft angles and injection points
- split lines and shear marks
understand
- how ribs and webs strengthen a moulded part
- the purpose of bosses, location pins, ribs and webs
Success criteria WILF
- I can identify flashing, ejector marks, draft angles and injection points
- I can explain how ribs and webs strengthen a moulded part
- I can identify split lines and shear marks
- I can explain the purpose of bosses, location pins, ribs and webs
Spotting how something was made
- Split lines: where two halves of a mould meet.
- Flashing: thin excess material squeezed out where the mould halves meet.
- Ejector pin marks: small circles where pins pushed the part out.
- Injection point / sprue: where material entered the mould.
- Draft angles: tapered sides for release.
- Wall thickness: even (rotational moulding), thin and varying (vacuum forming).
- Thinning of sheet material at corners (vacuum forming).
- Shear marks on cut edges (piercing and blanking).
- Surface finish: smooth (injection, die casting) or rough (sand casting).
- Symbols and labels: recycling codes and material marks moulded in.
Strengthening and assembly features
- Boss: a raised cylinder that takes a screw or thread; strengthens the area around the fixing.
- Location pin: positions parts accurately for assembly and stops them moving.
- Ribs and webs: thin walls that add strength and rigidity without thick sections, help material flow evenly into the mould, reduce distortion, and hold internal components (circuit boards, wires) in place.
- Also moulded clips and threads remove the need for separate fixings.
Exam link: what each feature is for HIGHER
| Feature | Purpose |
|---|---|
| Boss | Takes a screw that holds two halves together; strengthens the fixing point |
| Rib / web | Adds strength and rigidity without thicker walls; locates and holds internal parts such as a circuit board |
| Location pin | Lines two halves up exactly for assembly |
| Snap-fit clip | Joins plastic parts with no tools or separate fixings |
| Asymmetric parts | Only fit one way, so they can't be assembled wrongly |
Naming the feature on its own is not awarded: say what it does.
Key terms
| Boss | Raised cylinder to receive a screw; adds strength at the fixing. |
|---|---|
| Location pin | Positions mating parts accurately during assembly. |
| Ribs/webs | Add strength and rigidity, help material flow, locate internal parts. |
| Flashing | Thin excess material where the two halves of a mould meet. |
| Split line | Line where two halves of a mould meet. |
| Shear marks | Marks on edges cut by piercing or blanking. |
Quick check
1. What is the main purpose of a boss on an injection-moulded casing?
- To decorate the outside of the moulded casing
- To take a screw and strengthen the fixing point
- To let trapped air escape from inside the mould
- To show the recycling code where it can be seen
Show answer
B: To take a screw and strengthen the fixing point. Bosses receive screws.
2. Why are ribs added to the inside of a plastic casing?
- To make the casing heavier so it feels solid and expensive
- To give a better grip on the outside of the casing
- Add rigidity without thick walls and hold internal parts
- To use up any extra plastic left in the mould
Show answer
C: Add rigidity without thick walls and hold internal parts. Thin ribs stiffen the part and locate components.
3. Thin excess plastic along the edge of a moulded part is called…
- Draft
- Rib
- Ejector pin mark
- Flashing
Show answer
D: Flashing. Flash forms where the mould halves meet.
4. Location pins mainly help with…
- Accurate assembly
- Corrosion resistance
- Aesthetics
- Recycling
Show answer
A: Accurate assembly. They align parts.
Exam-style questions
1. Explain the purpose of location pins, bosses and ribs/webs. (4 marks)
Show marking guidance
- Location pins: position parts accurately; stop movement between parts
- Bosses: provide a space for a screw/thread; add strength at the fixing
- Ribs/webs: strength and rigidity; even material flow; locate internal components
- 1 mark per valid explanation
2. Describe the features of a product that identify it was injection moulded. (3 marks)
Show marking guidance
- Ejector pin marks (1)
- Split line with possible flashing (1)
- Injection point / sprue mark (1)
- Draft angles, bosses and ribs, high-quality finish (1)
Printable worksheet
An I do, we do, you do worksheet for this topic, with a separate answer sheet.