IntermediateTopic 45 of 100Materials & Chemical
Polymer processing
Injection moulding, extrusion and blow moulding shape plastics.
In depth
Injection moulding (most common), extrusion (pipes, profiles), blow moulding (bottles), thermoforming, compression and rotational moulding, 3D printing. Control temperature, pressure, cooling and orientation; design for flow, uniform wall thickness, draft and avoid sink marks and warpage.
Key points
- Melt temperature and mould temperature
- Weld lines
- Cycle time dominated by cooling
ExampleA bottle cap is injection-moulded in seconds.
What is Polymer processing?
Injection moulding, extrusion and blow moulding shape plastics.
Why is it important to understand polymer processing?
Polymer processing methods shape plastics into products at high volume and low cost, which is why they dominate consumer goods.
What is injection moulding?
Molten polymer is forced into a closed mould under pressure, cools and is ejected, which suits high-volume complex parts.
Why do moulded parts need draft angles?
Draft lets the part slide out of the mould without scraping, and it reduces the risk of damage or sticking.
How is Polymer processing used in practice?
Typical applications include making a bottle by blow moulding, producing a continuous pipe by extrusion and making a complex plastic housing in an injection-moulding machine.
What should I learn before Polymer processing?
Study "Glass transition temperature" first (topic 44 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Polymer processing?
Melt temperature and mould temperature. Weld lines. Cycle time dominated by cooling.
Can you give an example of Polymer processing?
A bottle cap is injection-moulded in seconds.
What comes after Polymer processing?
The next topic is "Composites", which builds directly on this one.
How difficult is Polymer processing?
It is classed as Intermediate in Materials & Chemical (topic 45 of 100). It is an intermediate topic. Work through the beginner topics in Materials & Chemical first.