Plastic processes Flashcards
What are the advantages of injection moulding?
- highly accurate
- very cheap per part
- very fast
- excellent surface texture
- complex shapes
- webs can be added for strength
What are the advantages of compression moulding?
- highly accurate
- very cheap per part
- fast
- excellent surface texture
- complex shapes
- webs can be added for strength
What are the advantages of extrusion?
- fast production
- accurate
- cheap process
- same cross-section throughout
- complex cross-sections are possible
What are the advantages of blow moulding?
- produces hollow parts
- accurate
- cheap
- fast
What are the advantages of rotational moulding?
- produces large hollow parts
- uniform wall thickness makes the product strong
- accurate
What are the advantages of vacuum forming?
- low cost of machinery makes it suitable for small scale production
- accurate and repeatable
- cheap
- fast
- least expensive process
What are the disadvantages of injection moulding?
- high set up costs
- have to hide visible identifying features
- flashing has to be removed
What are the disadvantages of compression moulding?
- high set up costs
- have to hide visible identifying features
- flashing has to be removed
What are the disadvantages of extrusion?
- high set up costs
- extrusions will have to be cut and assembled to make products
What are the disadvantages of blow moulding?
- high set up costs
- only small products can be produced due to the draw on the plastic
- split lines are visible
What are the disadvantages of rotational moulding?
- slow cooling time limits the speed of production
- high set up costs
- split lines are visible
- may require further work to make holes etc
What are the disadvantages of vacuum forming?
- draw on the plastic makes it weaker at the corners
What are the identifying features of injection moulding?
- injection marks
- ejector pin marks
- split lines
- high-quality surface finish
- flash
What are the identifying features of compression moulding?
- ejector pin marks
- split lines
- high-quality surface finish
- flash
What are the identifying features of extrusion?
- long parts with the same cross-section throughout
- lines/scratches along lenght
- shrinkage marks
- good surface finish
