The big idea: Three additive processes are used to make real parts, not models: powder bed fusion (PBF), selective laser sintering (SLS) and material extrusion.
They are chosen where tooling cannot be justified — low volumes, complicated shapes, or parts that must all differ.
What is inside each machine — and why a powder bed needs no support structures at all.
Interactive diagram
Explore the labelled diagram, charts and maps for this topic in full study mode.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Start Studying Free Full access to Aimnova Pro · cancel anytime
| Process | How it works | Materials and uses |
|---|---|---|
| Powder bed fusion (PBF) | A thin layer of powder is spread across a bed and a laser or electron beam fuses the cross-section; the bed drops and another layer is spread, with the unfused powder supporting the part | Metal powders — titanium, aluminium, stainless and tool steels. Aerospace brackets, turbine parts, surgical implants, dental frameworks |
| Selective laser sintering (SLS) | The same powder-bed idea with a polymer powder, usually nylon, sintered just below its melting point | Nylon and filled nylons. Functional production parts, jigs and short runs — and no support structures are ever needed |
| Material extrusion | A heated nozzle lays a bead of molten polymer along each layer, in a temperature-controlled chamber so the part does not warp as it cools | Engineering thermoplastics — ABS, polycarbonate, PEEK, carbon-filled grades. Tooling, jigs, fixtures, large low-volume parts, spares on demand |
The powder bed is the support: In PBF and SLS the surrounding unfused powder holds the part up, so no support structures are printed and none have to be removed.
That is why those processes can make shapes with internal cavities and overhangs that an extrusion machine could not attempt — and why the loose powder is recovered and reused.
Learn what examiners really want
See exactly what to write to score full marks. Our AI shows you model answers and the key phrases examiners look for.
Try AI Feedback FreeYour first topic is free to keep • No credit card required
| What changes | Why it matters |
|---|---|
| No tooling cost | The first part costs what the thousandth costs, so a run of fifty is viable where moulding would need fifty thousand |
| No minimum order | A spare can be printed on demand instead of stocked, which removes an inventory, a warehouse and a write-off |
| A design change is free | There is no tool to modify, so a revision costs a new file rather than a new die |
| Complexity is free | A lattice, an internal cooling channel or a topology-optimised shape costs no more to print than a solid block — sometimes less, because there is less material |
| Every part can differ | Which is what makes mass customisation possible at all |
The honest limits: Build volume caps the part size. Cycle times are hours, not seconds. Metal powders are expensive and need careful handling.
And a printed part needs qualification — the material, the machine settings and the post-processing all have to be controlled and recorded before it can be flown or implanted.
How this is tested — describing additive manufacturing techniques used in industry. It comes up two ways:
Paper 1 — multiple choice
- Identify a powder-bed process from a description.
- Choose the additive process suited to a metal part.
Paper 2 — analysing a product
- Describe how a named component is produced by an additive process.
- Explain why additive manufacturing was chosen for a low-volume part.
The trap: Forgetting that the powder bed is the support. It is why PBF and SLS can make shapes that extrusion cannot, and it is worth a mark on its own.
IB-style questionExplain[6 marks]
An aircraft manufacturer prints a titanium bracket by powder bed fusion instead of machining it from a billet. Explain why.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.