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Homework Help: Finding the time and cost it takes for manufacturing

  1. Mar 29, 2012 #1

    I'm looking for some help on an assignment I have been given!!
    I know how to do everything except to calculate the time it takes for the turning, milling and drilling processes.
    I would appreciate if you could give me the formulas along with the answer!!
    The component is attached as I could not post it here.

    Thanks a Million,
    Here is the assignment:

    You have been given the task of estimating the total cost of manufacturing 1000 components in your Engineering Company. The components (shown) are manufactured from high-grade steel using a lathe and a milling machine only.
    Using the following information estimate the total cost if production time is charged out at €25.00 per hour and material cost at €2.00 per piece.
    The first operation is turning. A tungsten carbide tool is used at a cutting speed of 60m/min and a feed rate of 0.06mm/rev. The second operation is milling. A face mill, 50mm diameter with 8 tungsten carbide inserts is used at a cutting speed of 60m/min and a feed rate of 0.1mm/tooth. The third operation is drilling. The drill is high-speed steel and is used on the milling machine at a cutting speed of 20m/min and a feed rate of 0.1 mm/rev. The depth of the hole is 27.1mm.
    Prorated downtime for all work set up procedures and transfer from lathe to milling machine is 1.25 minutes per component. Prorated downtime for tool changing on the milling machine is 4.4 minutes per component

    Attached Files:

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  2. jcsd
  3. Mar 29, 2012 #2


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    Staff Emeritus
    Science Advisor

    Well - use the rates for machining and the rates for down time to determine cost.

    One should be able to determine how long it takes to mill/machine each component and then multiply by the number of components to get the total time. Then multiply the time by the cost/unit time.
  4. Mar 29, 2012 #3
    I understand this but I don't know how to determine how long it takes to mill/machine each component!?
  5. Mar 29, 2012 #4


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    Staff Emeritus
    Science Advisor

    Look at the diagram and the dimensions of the blank vs the final piece.

    Over what length is the turning performed? How long does that take? Is there more than one pass?

    The second operation is the face milling. Over what length?

    The third operation is drilling - how many holes and to what depth?

    There is a tool change between face mill and drilling.
  6. Mar 29, 2012 #5
    I don't know... this is what i'm trying to figure out!?
  7. Mar 30, 2012 #6
    You have all the necessary data:
    Normally, the calculations require knowing depth-of-cut for each tool, but your drawing specifies the number of passes for each process (e.g., milling in one pass, turning in three). Just be careful to remember that the face-milling tool has eight cutting edges.
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