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Homework Help: Manufacturing Processes

  1. Sep 22, 2008 #1
    During pouring into a sand mold, the molten metal can be poured into the downsprue at a constant flow rate during the time it takes to fill the mold. At the end of pouring the sprue is filled and there is negligible metal in the pouring cup. The downsprue is 6 in. long. Its cross-sectional area at the top is 0.8 in^2 and the base is 0.6 in^2. The cross-sectional area leading from the sprue is also 0.6 in^2 and it is 8 in. long before leading into the mold cavity, whose volume is 65 in^3. The volume of the riser located along the runner near the mold cavity is 25 in^3. It takes a total of 3 sec to fill the entire mold. This is more than the theoretical time required, indicating a loss of velocity due to friction in the sprue and runner. Find

    a)the theoretical velocity and flow rate at the base of the downsprue
    b)the total volume of the mold
    c)the actual velocity and flow rate at the base of the sprue and
    d)the loss of head in the gating system due to friction

    I guess my problem is i dont know how to calculate actual differently from theoretical as I only know one way to calculate which I am not even too sure of. Could someone give me a push to start off?
    Last edited by a moderator: Sep 23, 2008
  2. jcsd
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