You are the manager of a workshop. You need to turn 1,500 shafts as an intermediate step in a...

   

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You are the manager of a workshop. You need to turn 1,500 shafts as an intermediate step in a larger manufacturing process. It takes your workshop technician 20 min to machine a single shaft at a cutting speed of 15 m/min and 10 min to set up the blank in the spindle. Since you are turning 1,500 shafts, the technician will certainly change the cutting tool to maintain quality - a tool change would require five minutes. The technician's hourly rate is QAR 350 per hour; your overhead cost is 200%. A local supplier sells you the blanks at the cost of QAR 250 per unit. The process has been traditionally done using a high-speed steel (HSS) cutting tool- these tools are available from a local supplier at the cost of QAR 10 per tool. A HSS cutting tool would provide high quality surface finish for 1 hour of cutting at the cutting speed of 15 m/min and then would need to be changed. However, to make (time and financial) savings, you want to investigate using a carbide cutting tool that the supplier offered to you at QAR 50 per tool. This carbide cutting tool would provide high quality surface finish for 6 hours of cutting at the cutting speed of 15 m/min. 1) Calculate the cost of machining the 1,500 shafts at the nominal cutting speed of 15 m/min for both cutting tools. 2) Assuming the same feed rate, how many tools will you use at 17.5 m/min for both the HSS and carbide tools. Notice that a higher cutting speed will lower the tool's life. You can use Taylor's tool life equation: V7 V to find the tool life at a cutting speed of 17.5 m/min. In this equation, V is the cutting speed, T is the tool life and n = 0.125 for HSS and 0.25 for carbide. 3) Calculate the total cost to your workshop for machining the 1,500 shafts: a) Using the HSS tool at 15 m/min (which is what your technician is doing now) b) Using the HSS tool at 17.5 m/min c) Using the carbide tool at 15 m/min d) Using the carbide tool at 17.5 m/min Tabulate your results so you can present them to the head of your business unit (highlight the biggest savings): Cost (QAR) Cost (% Change Time % Change] HSS at 15 m/min HSS at 17.5 m/min Carbide at 15 m/min Carbide at 17.5 m/min NA NA

Answer rating: 100% (QA)

SOLUTION 1 Cost of machining 1 500 shafts at the nominal cutting speed of 15 m min for both cutting tools For the HSS cutting tool Machining time per shaft 20 min includes 10 min for setup and 5 min f View the full answer