100% T View Zoom Add Category Insert Table Chart Text Shape Media Comment Collaborate Format Organize + Scheduling O A B C D E F G H I JK LM NOP QR ST U V W X Y Z AAABACADAE AF AGAH AI AJAK ALAMANAO AP AQ AR AS AT AU AV AW AX AY Chapter 12: Scheduling Operations N w Assignment 3 of 3: How should I schedule my jobs? Here's an example to test your skills at creating an effective -- and efficient -- production schedule. You are managing a highly custom Job Shop that repairs classic cars. Schedule the 5 5 jobs below based on the Critical Ratio to set your Priorities. (This is a small shop -- assume no wasted time moving from station to station.) Then, compute your schedule's performance metrics. Finally, to improve customer service you are considering doubling your equipment to have each worker run 2 machines at each station. Is this worth the expense? 6 7 Critical Ratio Typical options for dispatching jobs: 8 Job # Station/Hours Process time Due Time (Hour C R Priority (based on C/R) First come, first served (FCFS) 9 1 A/1 B/2 C/3 D/2 8 0.00 Priority rule Critical ratio = remaining time until due date 10 2 B/2 C/3 A/1 D/4 10 0.00 Preemptive rule remaining processing time 11 3 C /2 A/3 D/1 C /2 ).00 Critical ratio |4 00 00 00 12 4 4/2 D/2 C /3 B/1 .14 Shortest processing time 13 5 D/2 C/1 A/2 B/4 0.07 14 Total Processing time = 15 Gantt Chart Example mapping of Job #6 that requires A/3, B/3, C/2. 16 Hours Hours Hours Hours Hours 17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 2 3 4 5 6 7 8 18 A 6 6 A 6 19 complete your schedule here in the format of a Gantt Chart by typing 20 in the Job Number (e.g. 1, 2, 3..) in each block that will be worked Co 6 6 6 21 Color-coding is set using Conditional Format. Use the Critical Ratio 22 that you computed above to prioritize dispatching (1st, 2nd, 3rd... = 1, 6 6 23 2, 3....). See example on right. 24 25 Due 26 Time Completed by hour Job (hour) On-time (Y/N) Hours late 27 8 Note: Contract terms are rebate of $500 for each late job plus $50 per hour late. 28 10 29 8 30 14 31 12 32 33 Make Span = hours 34 Utilization= 35 On-Time rate= 0.0% 36 Total lateness= 0 hours 37 Cost of lateness = 38 Two Machines per Station Now, schedule again with renting an additional machine per station. Use the same Critical 39 Ratio prioritization. Gantt Chart 40 Hours Hours Hours Hours 41 Job # Station/Hours (same requirements as before) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 42 1 A/1 B/2 C/3 D/2 13 2 B/2 C/3 A/1 D/4 A2 C/2 N3 C/2 SUM AVERAGE MIN MAX COUNTA 276100% EE T View Zoom Add Category Insert Table Chart Text Shape Media Comment Collaborate Format Organize Scheduling O A B C D E F G H I J K L M NOP QR ST U V W X Y Z AA AB ACAD AE AF AGAH AI AJAK ALAMANAO AP AQ AR AS AT AU AV AW AX AY 14 31 5 12 32 33 |Make Span = hours 34 Utilization = A 35 On-Time rate= 0.0% 36 Total lateness= 0 hours 37 Cost of lateness = 38 Two Machines per Station 39 Now, schedule again with renting an additional machine per station. Use the same Critical Ratio prioritization. Gantt Chart 40 Hours Hours Hours Hours 41 Job # Station/Hours (same requirements as before) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 42 1 A/1 B/2 C/3 D/2 43 2 B/2 C/3 A/1 D/4 44 2 C/2 A/3 D/1 C/2 45 A/2 D/2 C/3 B/1 46 5 D/2 C/1 A/2 B/4 47 48 49 50 Due 51 Time Completed by hour Job (hour) On-time (Y/N) Hours late 52 8 53 10 Note: Contract terms are rebate of $500 for each late job plus $50 per hour late. UI AW NI 54 8 55 14 56 12 57 58 Make Span = hours Utilization On-Time rate= 0.0% Total lateness= 0 hours Cost of lateness = Variable cost of renting new machines (running or not): Additional cost of 2nd machines (during full Make Span) 65 10.00 per hour 66 A 15.00 per hour 67 ona 25.00 per hour 68 17.00 per hour 69 70 Total Additional Cost = |$ 71 72 Profit or Loss |$ - (positive is an overall benefit, negative is net loss) 73 74 What is your recommendation? Rent additional machines or not? Why? 75 ROI = SUM AVERAGE MIN MAX COUNTA 276