The principal forming techniques in this syllabus area are bending, casting, injection molding, and blow molding. They all create a required shape, but differ in material state, tooling, geometry, and scale.
Forming changes a material into a desired three-dimensional shape without primarily removing it. Selection depends on material properties, required accuracy, surface finish, production volume, tooling cost, and environmental impact.
| Technique | Mechanism and materials | Typical applications and considerations |
|---|---|---|
| Bending | A force plastically deforms sheet, rod, tube, or strip around a former or between a punch and die. Metals and thermoplastics are common. | Used for brackets, enclosures, frames, and furniture. Consider bend radius, springback, thickness, and cracking. |
| Casting | A liquid is poured into a mould, solidifies, and is removed. Metals, polymers, ceramics, and concrete can be cast. | Complex forms and internal cavities can be produced using cores. Consider shrinkage, porosity, finish, and mould cost. |
| Injection molding | Molten thermoplastic is forced under pressure into a closed metal mould, cooled, and ejected. | It suits accurate, complex parts at high volume. Expensive tooling enables low unit costs. Consider draft angles, uniform walls, ribs, and ejector marks. |
| Blow molding | A heated polymer parison or injection-molded preform is enclosed and inflated with compressed air. | It creates hollow, thin-walled bottles and containers. Consider wall-thickness control, seam lines, neck geometry, and mould cost. |
A common misconception is that injection molding and blow molding are interchangeable. Injection molding fills a mould cavity to make mainly solid components; blow molding expands material against the mould walls to make hollow products.
For an IB Design Technology A4.1 response, identify the material, describe the process sequence accurately, and justify the technique through product geometry and production volume. For a question, give similarities and differences; for , weigh advantages against constraints and reach a supported conclusion.
