Main Question or Discussion Point
While making a pattern for a casting do we increase or the bore diameter of the pattern, than actually required in the casting, taking into consideration the shrinkage allowance for metal?
Generally speaking, yes, but...So this is exactly what would happen during the cooling of a similar casting, after it has solidified?
Wikipedia said:... Some alloys will have overall linear shrinkage of up to 2.5%, whereas other alloys may actually experience no shrinkage or a slight "positive" shrinkage or increase in size in the casting process (notably type metal and certain cast irons). ...
Again, yes. The amount of change will depend on many things. Getting the "as cast" dimensions to meet your required tolerances may require considerable trial & error.Ok.. anyway for most metals (the ones that contract on cooling) the bore diameter will decrease during the shrinkage of casting, right?