ISE $2360$ Design for Manufacturing

Lecture Assignment $9$

Due date: Refer to the syllabus.

$1.$ Answer the following questions $(4$ pts $)$:

$(1)$ What are the differences between the cooling$/$solidification of pure metals and metal alloys?

$(2)$ Sketch the internal structure of a sand mold $($draw the internal structure and label the name of each feature$).$ Explain the purpose of pouring basin, sprue, runner, and riser.

$(3)$ List three expendable mold processes. Explain how each process works.

$(4)$ The figures below show two different designs for two castings. Which one is better? Explain why.

$2.$ Pure copper is poured into a sand mold. The metal level in the pouring basin is $10$ in $.$ above the metal level in the mold $($i$.$e$.,$ the bottom of the sprue$),$ and the cross section of the bottom of the sprue is circular with a $0\mathrm{.}4-$in$.$ diameter. What are the velocity and rate of the flow of the metal into the runner? $(2$pts$)$

$3.$ A sprue is $12$ in $.$ long and has a diameter of $5$ in $.$ at the top, where the metal is poured. The molten metal level in the pouring basin is taken as $3$ in $.$ from the top of the sprue for design purposes. $(2$ pts $)$

$($a$)$ What should be the diameter of the bottom of the sprue to avoid aspiration?

$($b$)$ If a flow rate of $\backslash (40\backslash$mathrm$\{$in$\}^\{3\}/\backslash$mathrm$\{$s$\}\backslash )$ is to be achieved, what should be the diameter of the bottom of the sprue? Will the sprue aspirate? Explain. Assume the flow is frictionless. Use g $=\backslash (386\backslash$mathrm$\{$in$\}/\backslash$mathrm$\{$s$\}^\{2\}\backslash ).$

$4.$ A cylinder with a diameter of $2\mathrm{.}0$ in $.$ and a height of $3$ in $.$ solidifies in three minutes in a sand$-$casting operation. What is the solidification time if the cylinder height is doubled? What is the time if the diameter is doubled? $(2$pts$)$