Chapter 4

You and three of your friends run a car wash for a fund-raiser. Between interior and exterior cleaning, you spend about 40 minutes per vehicle. You are so successful that the next day you invite four more friends to help. How does this impact the labor content?

The labor content stays the same.

When an operation improves its efficiency, its revenue will always stay constant, while its costs will go down.

False

It is possible to increase process capacity by balancing a process.

True

C&A operates three eight-hour shifts to produce 600 gallons of a chemical per day. It requires 12 minutes of labor to produce a gallon of the chemical. What is C&A's takt time in minutes per gallon, and what is the target manpower?

2.4, 5 Takt time = Available time/Required quantity = 3 × 8 hours/600 gallons = 0.04 hours per gallon = 2.4 minutes per gallon. Target manpower = Labor content/Takt time = 12 minutes per gallon/2.4 minutes per gallon = 5.

The bottleneck resource in a process has the least idle time.

True

Mr. K's is a very popular hair salon. It offers high-quality hairstyling and physical relaxation services at a reasonable price, so it always has unlimited demand. The service process includes five activities that are conducted in the sequence described next (the time required for each activity is shown in parentheses): Activity 1: Welcome a guest and offer homemade herb tea (10 minutes). Activity 2: Wash and condition hair (10 minutes). Activity 3: Neck, shoulder, and back stress-release massage (10 minutes). Activity 4: Design the hairstyle and do the hair (25 minutes). Activity 5: Check out the guest (5 minutes). Three servers (S1, S2, and S3) offer the services in a worker-paced line. The assignment of tasks to servers is the following: S1 does Activity 1, S2 does activities 2 and 3, and S3 does activities 4 and 5. a.What is the labor content? b.What is the average labor utilization? c.At a wage rate of $20 per hour, what is the cost of direct labor per customer? d.Mr. K considers hiring a new employee to help any one (and only one) of the servers without changing the tasks performed by each server. What will be the new direct labor? e.Mr. K contemplates redesigning the assignment of tasks to servers. For this, Mr. K is evaluating the reassignment of Activity 5 from S3 to S1. What will be the new direct labor? f.Mr. K is thinking to add one additional worker to the process. The worker would be assigned to the same set of tasksas one of the current workers. First, decide which set of tasks would benefit from one additional worker, then calculate the process capacity (customers per hour)? g.Suppose 4 minutes of processing time from activity 4 could be moved to activity 3 while keeping the task assignments the same. What would be the capacity of this new process (customers per hour)? h.Suppose each worker could be trained to complete all activities and they could all work independently of each other. What would be the capacity of this process (customers per hour)?

a. Labor content = 10 minutes Activity 1 + 10 minutes Activity 2 + 10 minutes Activity 3 + 25 minutes Activity 4 + 5 minutes Activity 5 = 60 minutes b. 60 minutes labor content / (3 employees × 30 minutes bottleneck) = 66.67% c. $60 per hour / 2 customers per hour = $30 per customer d. $80 per hour / 3 customers per hour = $26.67 per customer e. $60 per hour / (60/25) customers per hour = $25 per customer f. Add to S3. S2 is the new bottleneck. Capacity = 60 min/hr / 20 min per customer = 3 customers per hour g. S3 remains the bottleneck. Capacity = 60 min/hr / 26 min per customer = 2.31 customers per hour h. 3 workers × 60 min/hr / 60 min/customer = 3 customers per hour.