Question

Feeding of an alloy in the mould is considered to be difficult if centre-line feeding resistance (CFR) is_____

(a) greater than 70%

(b) less than 70%

(c) less than 20%

(d) 0%

This question was addressed to me in examination.

Question is from Rate of Solidification topic in division Cooling and Solidification of Casting-Forming-Welding I

Answer 1

Right choice is (a) greater than 70%

Best explanation: The difficulty of feeding an alloy in a mould is expressed by a quantity which is commonly known as centre-line feeding resistance (CFR). It is basically defined as the ratio of a time interval between start and end of freezing at centre line to the total solidification time of casting. Normally, feeding is considered to be difficult if CFR is greater than 70%.