Performance time Task must follow task listed below A 4 - B 7 - C 6 A,B D 5 C E 6 D F 7 E G 8 E H 6 F,G. Task

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1 South arolina urniture Inc. produces all types of office furniture. The executive secretary is a chair that has been designed using ergonomics to provide comfort during long work hours. The chair sells for $ 130. There are 480 minutes available during the day, and the average daily demand has been 50 chairs. There are eight tasks: Task Performance time Task must follow (min) task listed below , , a) raw a precedence diagram of this operation b) What is the cycle time for this operation c) What is theoretical minimum number of workstations d) ssign tasks to workstations e) ow much total idle time is present each day f) What is the overall efficiency of the assembly line Solution a) Precedence diagram

2 b) ycle time = Production time available per day Unit required per day = 480 minutes 50 chairs = 9.6 ~ 10 min/chair c) Total task time = = 49 min Minimum number of workstations = Total task time = 49 min ycle time 10 min = 4.9 ~ 5 workstations d) Tasks to workstation Station 1 4 min 6 min Station 3 Station 4 Station 5 Station 7 5 min 6 min 7 min Station 6 6 min Station 2 7 min 8 min Since the tasks time in workstation must be not exceeding the cycle time. Then, total workstation is 7.

3 e) Idle time Idle times are in workstation 2 = 3 min, workstation 3 = 5 min, workstation 4 = 4min, workstation 5 = 3min, workstation 6 = 2 min, workstation 7 = 4 min and total idle time is 2utes f) fficiency fficiency = ( ) min = 49 (7 workstations) x (10min) 16 = 70%

4 Mach 10 is a one person sailboat designed to be used in ocean. Manufactured by reative Leisure, Mach 10 can handle 40 mph winds seas over 10 feet. The final assembly plant is in upertino, alifornia. t this time, 200 minutes are available each day to manufacture Mach 10. The daily demand is 60 boats. iven the following information, a) raw the precedence diagram and assign tasks to the fewest workstations possible. b) What is the efficiency of the assembly line c) What is the theoretical minimum number of workstations d) What is the idle time Task Performance Time Task must follow Task listed below ,, 2 I 1, Solution a) Precedence diagram and fewest workstation ycle time = Production time available per day Unit required per day = 200 minutes 60 chairs = 3.33 ~ 4 min/chair

5 Station 2 Station 3 Station 4 Station 1 I b) fficiency of assembly line fficiency = ( ) min = 13 (4 workstations) x (4 min) 16 = 81.25% c) Theoretical minimum number of workstation No of workstation = total task time = 13 ycle time 4 = 3.25 or 4 workstations

6 d) Idle time Station 2 Station 4 Station 1 2 min Station 3 3 min I 2 min Idle times are in workstation 1 =, workstation 2 =, workstation 3 = 1min and total idle time is 3 minutes

7 r. Lori aker, operation manager at Nesa lectronics, prides herself on excellent assembly line balancing. She has been told that the firm needs to complete 96 instruments per 24 hour day. The assembly line activities are: Task Time (min) Predecessors , , I 1 J 6 K 4,I,J a) raw precedence diagram b) If the daily (24- hour) production rate is 96 units, what is the highest allowable cycle time c) If the cycle time after allowances is given as 10 minutes, what is the daily (24 hour) production rate d) What a 10 minute cycle time, what is the theoretical minimum number of station with which the line can be balanced e) What a 10 minutes cycle time and six workstations, what is the efficiency f) What is the total idle time per cycle with a 10 minute cycle time and six workstations g) What is the best workstation assignment you can make without exceeding a 10 minute cycle time and what is its efficiency

8 Solution: a) I K J b) ycle time ycle time = (24 hours) (60 minutes/ hours) 96 units = 15 minutes/unit c) Production rates Production rates = cycle time x production units = (10 min/unit) (96 units) = 960 minutes

9 d) Minimum workstations No of workstation = Total time ycle time = ( ) min 10 min = 5 workstations e) fficiency fficiency = 50 min (6 workstations) (10 min/units) = 83.33%

10 f) Workstations Station 1 Station 2 Station 3 Station 6 3 min 7 min 4 min 5 min Station 4 Station 5 K 5 min 7 min I 4 min 6 min 2 min J 6 min Idle times are in workstation1 =, workstation 2 = 3 min, workstation 3 = 1 min, workstation 4 =, workstation 5 = 3 min, workstation 6 = and total idle time is 10 minutes

11 g) the best workstation assignment you can make without exceeding a 10 minute cycle time and its efficiency Station 1 Station 2 Station 3 Station 6 3 min 7 min 4 min Station 4 I 5 min K 5 min 7 min 4 min Station 5 J 6 min 2 min 6 min fficiency = 50 min (6 workstations) (9 min/units) = 92.6%