Manufacturing Engineering (Lectures 9-13) Flashcards
What is permanent pattern casting?
A pattern (often metal) Is used to take an impression. The mould is destroyed on de-moulding but the pattern is used many times. E.g. sand casting.
What is permanent mould casting?
A single mould is used for many repeat castings. Mould needs to be metal, and high grade tool material is needed to withstand the temperature changes. E.g. die casting
What is a shrinkage cavity?
Depressions in the surface or significant sub surface voids. It is caused by shrinkage upon solidification of a liquid. The areas that are the last to cool there is insufficient liquid compared to the region of tool remaining. It can be offset by a good riser (feeder design).
What is high pressure die casting?
A similar process to injection moulding. High forces from a plunger force liquid into a closed die.
Gravity fed casting?
Cheap but can lead to the introduction of air forming oxides, which can lead to defects.
Investment casting?
A modern process of expendable mould and pattern casting. The pattern is made in wax, and the mould built around it. The wax is burnt off due to the high temperature and the cast is formed. Destructive de-moulding.
