operations 6&7

Chapter 6 problems

4. A production manager at Ultra Clean Dishwashing Company is monitoring the quality of the company's production process. There has been concern relative to the quality of the operation in accurately filling the 16 ounces of dishwashing liquid. The product is designed for a fill level of 16.00 ± 0.30. The company collected the following sample data on the production process:

Observations

· (a) Are the process mean and range in statistical control?

(b) Do you think this process is capable of meeting the design standard?

6. The Awake Coffee Company produces gourmet instant coffee. The company wants to be sure that the average fill of coffee containers is 12.0 ounces. To make sure the process is in control, a worker periodically selects at random a box of six containers of coffee and measures their weight. When the process is in control, the range of the weight of coffee samples averages 0.6 ounces.

· (a) Develop an R-chart and an -chart for this process.

· (b) The measurements of weight from the last five samples taken of the six containers follow:

Is the process in control? Explain your answer.

10. University Hospital has been concerned with the number of errors found in its billing statements to patients. An audit of 100 bills per week over the past 12 weeks revealed the following number of errors:

Week	Number of Errors
1	4
2	5
3	6
4	6
5	3
6	2
7	6
8	7
9	3
10	4
11	3
12	4

· (a) Develop control charts with z = 3.

(b) Is the process in control?

Chapter 7

2. A manufacturer of thermostats uses a kanban system to control the flow of materials. The packaging center processes 10 thermostats an hour and receives completed thermostats every 30 minutes. Containers hold 5 thermostats each.

· (a) How many kanbans are needed for the packaging center?

· (b) If management decides to keep two thermostats as safety stock, how many kanbans will be needed?

A production cell at Canderberry Candle facility operates 5 hours per day and uses a pull method to supply wicks to the assembly line. The wicks are used at a rate of 300 per day. Each container holds 20 wicks and usually waits 20 minutes in the production cell. Management wants a safety stock of 10 percent. How many containers should be used at the Canderberry Candle facility for purposes of pull production?

4. Carlos Gonzales is production manager at an assembly plant that manufactures cordless telephones. The company is planning to install a pull system. The process is being planned to have a usage rate of 50 pieces per hour. Each container is designed to hold 10 pieces. It takes an average of 30 minutes to complete a cycle.

· (a) How many containers will be needed?

· (b) How will the number of needed containers change as the system improves?

6. Anna works on an assembly line where it takes her 30 minutes to produce 20 units of a product needed to fill a container. It takes her an additional 5 minutes to transport the container to Josh, who works at the next station. The company uses a safety stock of 20 percent. The current assembly line uses five kanbans between Anna's and Josh's stations. Compute the demand for the product.

8. Consider the information from Problem 7. Determine how the number of kanbans and the inventory level will be affected if the time required for Robert to receive the material increases to 30 minutes.