Question

3. Illinois Furniture, 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 48 chairs. the eight tasks required to produce the chair and the precedence diagram are shown below TASK PERFORMANCE TIME (min) ULUI Precedence diagram a. What is the cycle time for this operation? [1point] Cycle time = b. What is the theoretical minimum number of workstations? [1point] minimum number of workstations = C. Assign tasks to workstations. [3 points] [you may use the following table for your answer, add or delete columns, or develop your own] Workstation 1 2 Assigned Tasks d. What is the idle time per cycle? (2 points) idle time per cycle = e. How much total idle time is present in an 8-hour shift? [2 points] total idle time is present in an 8-hour shift= f. What is the efficiency of the assembly line, given your answer in () [ 1 point] efficiency of the assembly line =

Answer 1

1. Cycle time of operation = 480 minutes available time / 48 chairs = 10 minutes/ chair
2. Total duration of all tasks A to H = 4+7+6+5+6+7+8+6 minutes = 49minutes

Theoretical minimum number of workstations

= Total duration of all tasks/ cycle time of operation

= 49/10 = 4.9 ( 5 rounded to nearest whole number )

THEORETICAL MINIMUM NUMBER OF WORKSTATIONS = 5

3. Assignment of tasks to workstations ( total duration of tasks assigned to any workstation shall not exceed cycle time. Also a successive operation should not start until all other preceeding operations have been complete ) :

Workstation	Tasks	Total duration	Idle time = Cycle time – total duration
1	A	4	10 – 4 = 6
2	B	7	10 – 7 = 3
3	C	6	10 – 6 = 4
4	D	5	10 – 5 = 5
5	E	6	10 – 6 = 4
6	F	7	10 – 7 = 3
7	G	8	10 – 8 = 2
8	H	6	10 – 6 = 4

4. Idle time per cycle = 6 + 3+ 4 +5 +4+3+2+4 =31 minutes
5. Idle time of 31 minutes recorded for 1 office furniture

Therefore, total idle time in 8 hour shift i.e. for 48 chairs = 31 x 48 = 1488 minutes

6. Efficiency of the assembly line

= Total duration of all tasks/ ( actual number of workstations x cycle time) x 100

= 49/ ( 8 x 10 )   x 100

= 49/80 x 100

= 61.25%