Why flow rate is determined by assembly which does not has lowest capacity?

(Window Boxes) Metal window boxes are manufactured in two process steps: stamping and assembly. Each window box is made up of three pieces: a base (one part A) and two sides (two part Bs). The parts are fabricated by a single stamping machine that requires a setup time of 120 minutes whenever switching between the two part types. Once the machine is set up, the processing time for each part A is one minute while the processing time for each part B is only 30 seconds. Currently, the stamping machine rotates its production between one batch of 360 for part A and one batch of 720 for part B. Completed parts move from the stamping machine to the assembly only after the entire batch is complete. At assembly, parts are assembled manually to form the finished product. One base (part A) and two sides (two part Bs), as well as a number of small purchased components, are required for each unit of final product. Each product requires 27 minutes of labor time to assemble. There are currently 12 workers in assembly. There is sufficient demand to sell every box the system can make. a. What is the capacity of the stamping machine? b. What batch size would you recommend for the process? Step 4 of 4 ^ b. Compute the flow rate of the assembly process as follows: There are 12 workers in the assembly process. Each final assembly takes 27 minutes to complete. 12 0.444 units per minute 27 Therefore, the effective flow rate is = Compute the recommended batch size using the following formula: Flow ratex Setup time Recommended batch size 1-Flow rate Processing time per unit 0.444x 240 1-0.444x2 = 960 So, the recommended batch size will be 960 units. Comment