Question

The White Tooth Device Company is a manufacturer of high-end electric toothbrushes. For each toothbrush, there are a sequence of assembly steps performed by five workers. Each worker does two tasks. Workers are paid $24 per hour. Time (seconds) Task Worker T1 A 51 A T2 44 В тЗ 10 В T4 13 C Т5 29 C T6 14 T7 20 D T8 17 Е T9 44 Е T10 38 Instruction: Round "cost of direct labor" and "average labor utilization" to 2 decimal places. Round "target manpower" and "capacity of the process" to 1 decimal place. a. What is the labor content of a toothbrush (seconds)? b. What is the cost of direct labor for a toothbrush ($)? c. What is the utilization (as a percent) of worker A? d. What is the average labor utilization of this process? Suppose demand is 50 toothbrushes per hour. What is the е. takt time (seconds)?

Answer 1

worker	time
1	95
2	23
3	43
4	37
5	82

Answer a: Labor content = sum of task time =95+23+43+37+82 = 280 secs

Worker 1 is the bottleneck of the process, because worker 1 takes 95 secs to perform his tasks. Its process capacity is 60/95= 0.63 units per min or 37.89 units per hour

Direct labour cost per unit = total wages per hour/ units per hour

wages per hour= $ 24

Answer b: Direct labour cost per unit = $24*5/37.89 =$3.17 per toothbrush

Answer c: cycle time= 95 secs, idle time for worker A= 0 secs

labor utilization worker A= effective cycle time/cycle time of the system= 95/95= 1.0

Answer d: idle time= bottleneck time- process time

worker	process time	idle time= 95-process time
1	95	0
2	23	72
3	43	52
4	37	58
5	82	13
Total	280	195

• Average labor utilization = total labour content / (labour content + total idle time)

Average labour utilization= 280/(280+195)= 0.59