Questions 911 In a simple four step manufacturing process th

Questions 9-11 In a simple four step manufacturing process, the scrap rates for processes 1.2. 3, and 4 are 3%, 4%, 5%, and 5% respectively. The demand is 1000 good parts per shift (8-hr shift). Assume the scrap costs for processes 1, 2, 3, and 4 are $5 $6, $7, and $10 respectively. The standard times for processes 1, 2, 3, and 4 are 5, 6, 8, and 10 min respectively 9. What is the required input to the first process to meet this demand? 10. What is the total scrap cost for this manufacturing system? 11. Find the number of machine fractions (do not round) needed per shift (8-hr shift) for each process. Assume 80% efficiency and 90% reliability for each process

Solution

9)

Input to process 4 = 1000/(1-5%) = 1052.6

Input to process 3 = 1052.6/(1-5%) = 1108

Input to process 2 = 1108/(1-4%) = 1154.2

Input to process 1 = 1154.3/(1-3%) = 1190

Required input to the first process to meet this demand = 1190

10)

Scrap out of process 1 = 1190*3% = 35.7

Scrap out of process 2 = 1154.3*4% = 46.2

Scrap out of process 3 = 1108*5% = 55.4

Scrap out of process 4 = 1052.7*5% = 52.64

Total scrap cost = 35.7*5 + 46.2*6 + 55.4*7 + 52.64*10 = $ 1370

11) Machines needed for process 1 = (1190 units * 5 minutes) / (8 hours * 60 minutes per hour * 80% efficiency * 90% reliability) = 17.22

Machines needed for process 2 = (1154.3 units * 6 minutes) / (8 hours * 60 minutes per hour * 80% efficiency * 90% reliability) = 20.04

Machines needed for process 3 = (1108 units * 8 minutes) / (8 hours * 60 minutes per hour * 80% efficiency * 90% reliability) = 25.65

Machines needed for process 4 = (1052.7 units * 10 minutes) / (8 hours * 60 minutes per hour * 80% efficiency * 90% reliability) = 30.46