Massachusetts Institute of Technology 2.008: Design and Manufacturing II Problem Set 4 Problem Set 4 We would like to distribute our favorite solution for each problem to the class as the official solution so please strive for clarity and elegance. Problem 4-1. Welding Speed (a) Plot welding speed as a function of weld pool depth for depths s = 1mm to 25mm at two preheat temperatures, Tp = 70F and Tp = 700F. Plot the two curves on the same graph [consider using a spreadsheet to do this]. Show any formulas that you derive. (b) Explain what the point of this exercise is, ie., how does this shape how you design a part and the process that you use to make the part when welding is involved. Problem 4-2. Cutting model (a) Estimate the rate of production for the part in Figure 1 using the parameters from the following table. You may assume the part enters the cutting process as a rod that is 2.3 inches long at a radius of 1 inch. Plot the amount of power (in hp) required during the cutting of turning of this part. w Width of Cut 0.100 in f Feed Rate 0.020 in/rev α Rake angle 10 deg ω Spindle speed 400 rev/min µf Friction specific Energy 0.10 hp/min/in3 µs Shear specific Energy 0.40 hp/min/in3 C Taylor tool constant 350 n Taylor tool exponent 0.45 tc Cost per tool $20 (b) What is the tooling cost per part as a function of ω? [Note, the velocity changes during the two passes]. Use a spreadsheet to plot the tool cost vs Vc for values from 350 rev/min to 450 rev/min. 1R 1" 0.3" 2" R 0.6" Figure 1: Milled Flange
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