1. Line Balancing

2. Example problem - Golf Club mfg/assy firm Customer demand requires production volume of 24 finished clubs in an 8 hour shift Customer demand requires production volume of 24 finished clubs in an 8 hour shift task task description operation time (min) mustfollow Ainspection5- B trim the shaft to length 4A C weight the head 13A D finish the shaft 9B E clear coat the head 7C F assemble the head to the shaft 6 D, E total work content 44

3. Example problem - Golf Club mfg/assy firm (cont.) How often does a club need to come off the line in order to meet the customer demand required? How often does a club need to come off the line in order to meet the customer demand required? –Exclude initial start-up –Cycle time = (480 min/shift)/(24 clubs/shift) = 20 min/club –Takt time (for this example, same as cycle time as defined above) Takt time = available work time/customer demand Takt time = available work time/customer demand Aligns output of a process with customer demand (or the pull of the customer) Aligns output of a process with customer demand (or the pull of the customer) “Takt” is a German word referring to the rhythm or beat of music “Takt” is a German word referring to the rhythm or beat of music –Theoretical minimum number of workstations for this operation Total work content/cycle time Total work content/cycle time 44 min/20 min per workstation = 2.2 workstations → 3 workstations 44 min/20 min per workstation = 2.2 workstations → 3 workstations

4. LOT heuristic LOT – longest operation time heuristic LOT – longest operation time heuristic –Construct precedence diagram –Arrange tasks in order of longest to shortest –Take care of longest operations first (easier to fit in shorter operations later), while maintaining precedence and not exceeding cycle time

5. Apply LOT to Golf Club mfg/assy firm Precedence diagram Precedence diagram Tasks in order of longest to shortest Tasks in order of longest to shortest C – 13 min D – 9 min E – 7 min F – 6 min A – 5 min B – 4 min

6. Apply LOT to Golf Club mfg/assy firm (cont.) Efficiency of the line Efficiency of the line = (total work content)/(# of workstations x cycle time) = (44 min)/(3 workstations x 20 min/workstation) = 0.733 (73.3%) Where is the bottleneck? Where is the bottleneck? –Capacity fully utilized –Work-in-process inventory builds up in front of workstation 2 stations123 tasks A, C E, B, D F time per club 18 min 20 min 6 min time available per unit 20 min idle time 2 min 0 min 14 min

7. Evaluate investment options for Golf Club mfg/assy firm Investment options Investment options –Invest in equipment that will automate weighting process (task C) resulting in a savings of 4 min/club –Invest in fixturing for the shaft that will result in a savings of 2 min each for trimming (task B) and finishing (task D) Apply LOT rule to each option and see if there is any improvement in efficiency possible Apply LOT rule to each option and see if there is any improvement in efficiency possible

8. Balancing another manufacturing line For a manufacturing line, the data below on the task precedence relationships exist (assume the tasks cannot be split) For a manufacturing line, the data below on the task precedence relationships exist (assume the tasks cannot be split) taskperformance time (min) mustfollow A3- B6A C7A D2A E2A F4 C, B G5C H5 D, E, F, G

9. Balancing another manufacturing line (cont.) Construct the precedence diagram for the tasks. Construct the precedence diagram for the tasks. What is the theoretical minimum cycle time? What is the theoretical minimum cycle time? To balance the line to the cycle time determined above, what is the minimum number of work stations? To balance the line to the cycle time determined above, what is the minimum number of work stations? Use the "longest-operation-time" rule to balance the line to the theoretical minimum cycle time determined above. Use the "longest-operation-time" rule to balance the line to the theoretical minimum cycle time determined above. Calculate the efficiency of the balanced line. Calculate the efficiency of the balanced line.