e) The housing for a certain machinery product is made of two components, both aluminum castings. The larger component has the shape of a dish sink and the second component is a flat cover that is attached to the first component to create an enclosed space for the machine parts. Sand casting is used to produce the two castings, both of which are plagued by defects in the form of misruns and cold shuts. The foreman complains that the thickness of the parts is too thin, and that is the reason for the defects. However, it is known that the same components are cast successfully in other foundries. What other explanation can be given for the defects?