Engineering 29 Instructor: Brian Salazar
Engineering 29 - Manufacturing and Design Communication
Homework 5
Please use this document as a template, and write your responses in the provided blanks.
Recall signi cant gures.
1. A mold has a downsprue of length = 15 cm. The cross-sectional area at the bottom of the
sprue is 3.125 cm². The sprue leads into a horizontal runner which feeds the mold cavity, whose
volume is 1172 cm³. Determine:
(a) the velocity of the molten metal flowing through the base of the downsprue, assuming that it
is poured starting from a stationary state at the top of the downsprue
Spring 2024 University of California, Berkeley
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Engineering 29 Instructor: Brian Salazar
(b) the volume rate of flow
(c) the time required to fill the mold cavity
Spring 2024 University of California, Berkeley
Engineering 29 Instructor: Brian Salazar
2. The total solidification times of three potential riser shapes are to be compared:
I. a sphere with diameter 10. cm,
II. a cylinder with diameter and length both of 10. cm, and
III. a cube with side length 10. cm.
Assume that Cm=3.5 min / cm². The same metal alloy is used in all three cases
(a) Determine the solidification time for each geometry
Spring 2024 University of California, Berkeley
Engineering 29 Instructor: Brian Salazar
(b) Based on the results of part (a) and any other considerations that you consider relevant,
which geometric element would make the best riser?
(c) Provide an example of a sand casted component that would require the use of at least 1
core.
Spring 2024 University of California, Berkeley
Engineering 29 Instructor: Brian Salazar
3. (a) You injection molded the following part and noticed the circled defect. What is the name of
that defect? Provide some suggestions as to what you could do to prevent that defect
(b) Select a manufacturing process from the following list. For that manufacturing process,
explain how it operates. Your explanation should be brief (max of 4 sentences). Options:
vacuum molding, rolling, drawing, deep drawing, forging.
Spring 2024 University of California, Berkeley
