In this chapter, the following content will be discussed: Types of layout design, work cells continued, repetitive and product oriented layout, types, macdonald’s assembly line, disassembly lines, assembly line balancing, cycle time, output capacity,...
LECTURE 13 LSM733-PRODUCTION OPERATIONS MANAGEMENT By: OSMAN BIN SAIF Summary of last Session § Innovation at Macdonald’s – Case § Strategic Importance of Layout Decision § Objectives in Layout design § Higher Utilization § Improved Flow § Improved Employee § Improved Customer / Client § Flexibility Summary of last Session (Contd.) § Types of Layout I II III IV V VI Office layout Retail layout Warehouse layout Fixed-position layout Process-oriented layout Work-cell layout Agenda for this session • Types of Layout design – • Work Cells Continued Repetitive and Product Oriented Layout – Types – Macdonald’s assembly line • Disassembly Lines • Assembly line balancing • Cycle time Agenda for this session (Contd.) – • Cycle time determination Wing component example – Determining the efficiency Process Flows before the Use of Work Cells Process Flows after the Use of Work Cells Automated Manufacturing Cell Source: J T Black, “Cellular Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983) Advantages of Work Cells Reduced work-in-process inventory Less floor space required Reduced raw material and finished goods inventory Reduced direct labor, and setup cost Heightened sense of employee participation Increased use of equipment and machinery Reduced investment in machinery and equipment Improving Layouts Using Work Cells Current layout workers in small closed areas Improved layout - crosstrained workers can assist each other Figure 9.10 (a) 10 Cycle Time Cycle time is the maximum time allowed at each workstation to complete its set of tasks on a unit 26 Example 1: Cycle Times 0.1 0.7 1.0 With workstations, CT = 0.5 1.0 minute Cycle time of a system = longest processing time in a workstation 27 0.2 Example 1: Cycle Times 0.1 0.7 1.0 With workstation, CT = 0.5 0.2 2.5 minutes Cycle time of workstation = total processing time in of tasks With workstations, can CT = 1.0 minute? 0.1 0.7 Workstation 1.0 Workstation 0.5 0.2 Workstation 28 Output Capacity OT Output capacity = CT OT = operating time per day CT = cycle time Example: hours per day OT = x 60 = 480 minutes per day Cycle Time = CT = 1.0 Output = OT/CT = 480/1.0 = 480 units per day Cycle Time = CT = 2.5 Output = OT/CT = 480/2.5 = 192 units per day 29 Cycle Time Determined by Desired Output OT CT = cycle time = D D = Desired output rate Example: hours per day OT = x 60 = 480 minutes per day D = 480 units per day CT = OT/D = 480/480 = 1.0 Minute 30 Theoretical Minimum Number of Stations Required Nmin = ∑ ∑ t CT t = sum of task times Nmin = theoretical Minimum Number of Workstations Required Example: hours per day, desired output rate is 480 units per day CT = OT/D = 480/480 = 1.0 Minute Nmin = ∑t /CT = 2.5/1.0 = 2.5 stations ≈ stations 31 Wing Component Example Performance Time Task (minutes) A 10 B 11 C D E 12 F G H 11 I Total time 66 Immediate Predecessors — A B B A C, D F E G, H This means that tasks B and E cannot be done until task A has been completed 32 Wing Component Example Performance Time Task (minutes) A 10 B 11 C D E 12 F G H 11 I Total time 66 Immediate Predecessors — A B B A C, D F E G, H 10 11 A B 12 C F G D 11 E I H 33 Figure 9.13 Wing Component Example Performance Time Task (minutes) A 10 B 11 C D E 12 F G H 11 I Total time 66 480 Task Must Follow Task Listed Below 40 available mins per day units required — A Production time B available per day Cycle B time = Units required per day A = 480 / 40 C, D = 12 minutes per unit C F 10 11 n E ∑ Time for task i F A B G Minimum G, H time number of = i = Cycle workstations 12 D 11 I = 66 / 12 E H = 5.5 or stations 34 Figure 9.13 Wing Component Example Line-Balancing Heuristics Longest task time Choose the available 480 task available Performance Task Must Follow with the longest task time mins per day Time Task Listed 40 task units Task2 (minutes) Most following Below Choose the available required tasks10 number of= 12 mins A —with the largestCycle time B 11 Afollowing tasksMinimum = 5.5 or C B workstations Ranked positional Choose the available task for D Bwhich the sum of following weight4 E 12 Atask times is the longest F C, D Shortest task the available task C G FChoose 10 shortest 11 time with the task time H 11 E A B G F I G, H Least number of Choose the available task with the least number of Totalfollowing time 66 tasks D I 12 11 following tasks E H Table 9.4 35 Figure 9.13 Wing Component Example Performance Time Task (minutes) 480 Task Must Follow Task Listed Below A 10 B 11 Station C 52 D 11 E 10 12 B F A G H 11 I 12 Total Stationtime 66 E Station — A B C B A F C, D F D E Station Station G, H available mins per day 40 units required Cycle time = 12 mins Minimum workstations = 5.5 or G I 11 Station 6 Station H Station Figure 9.14 36 Wing Component Example Performance Time Task (minutes) Task Must Follow Task Listed Below 480 available mins per day 40 units required Cycle time = 12 mins Minimum workstations = 5.5 or A 10 — B 11 A C B D B E 12 A F C, D ∑ Task times G F Efficiency = (Actual number ofEworkstations) x (Largest cycle time) H 11 I G, H = 66 minutes / (6 stations) x (12 minutes) Total time 66 = 91.7% 37 Summary of this session • Types of Layout design – • Work Cells Continued Repetitive and Product Oriented Layout – Types – Macdonald’s assembly line • Disassembly Lines • Assembly line balancing • Cycle time 38 Summary of this session (Contd.) – • Cycle time determination Wing component example – Determining the efficiency 39 THANK YOU 40 ... Product-Oriented Layouts Advantages Low variable cost per unit Low material handling costs Reduced work-in-process inventories Easier training and supervision Rapid throughput Disadvantages High production. .. Manufacturing Systems Reduce Setup Time, Make Small Lot Production Economical.” Industrial Engineering (November 1983) Advantages of Work Cells Reduced work-in-process inventory Less floor space required... because work may not be divided evenly Improved layout - in U shape, workers have better access Four cross-trained workers were reduced U-shaped line may reduce employee movement and space requirements