Answer:
Solidification time is 2.78 min.
Step-by-step explanation:
Chvorinov's rule states that the solidification time is directly proportional to the square of ratio of total volume to the total surface area of the cast.
Step1
Given:
Chvorinov's rule constant is 4 min/cm².
Length of the rectangular cast is 30 cm.
Width of the rectangular cast is 15 cm.
Thickness of the rectangular cast is 20 mm or 2 cm.
Calculation:
Step2
Volume of the cast is calculated as follows:


V = 900 cm³.
Step3
Total surface area is calculated as follows:
A=2(lb+bt+tl)

A=1080 cm².
Step4
Time of solidification is calculated as follows:


t = 2.78 min.
Thus, solidification time is 2.78 min.