Question
Download Solution PDFMore Shrinkage allowance is considered in pattern-making for the casting of
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
Shrinkage Allowance
- During cooling of the material in the Casting process the molten metal tries to shrink in size because of the increase in the density, in all the three stages, the material is getting shrunk (reducing its dimensions or volume).
- But shrinkage allowance taking place in 1st two stages is called Liquid Shrinkage. Shrinkage is 3rd – the stage is called Solid shrinkage.
- Liquid shrinkage is always compensated by providing a riser in the casting process.
- Solid shrinkage is compensated by the giving shrinkage allowance. It is expressed as mm/m.
- Shrinkage values for different metal
- Bismuth – Negligible
- White metal (Tin) – 5 mm/m
- Cast Iron – 10 mm/m
- Aluminium – 13 mm/m
- Brass – 15 mm/m
- Copper – 17 mm/m
- Steel – 20 mm/m
- Zinc – 24 mm/m
- Lead - 26 mm/m
- So out of given options Lead has the highest shrinkage allowance value.
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