Question: Izbar Precision Casters, Inc. Izbar Precision Casters, Inc., manufactures a variety of structural steel products for the construction trade. Currently, there is a strong demand for its I-beam product produced at a mill outside Memphis. Beams at this facility are shipped throughout the Midwest and mid-South, and demand for the product is high due to the strong economy in the regions served by the plant. Angie Schneider, the mill's manager, wants to ensure that the plant's operations are in control, and she has selected several characteristics to monitor. Specifically, she collects data on the number of weekly accidents at the plant, the number of orders shipped on time, and the thickness of the steel I-beams produced. For the number of reported accidents, Angie selected 30 days at random from the company's safety records. Angie and all the plant employees are very concerned about workplace safety, and management, labor, and government officials have worked together to help create a safe work environment. As a part of the safety program, the company requires employees to report every accident regardless of how minor it may be. In fact, most accidents are very minor, but Izbar still records them and works to prevent them from recurring. Because of Izbar's strong reporting requirement, Angie was able to get a count of the number of reported accidents for each of the 30 sampled days. These data are shown in Table 2.
To monitor the percentage of on-time shipments, Angie randomly selected 50 records from the firm's shipping and billing system every day for 20 different days over the past six months. These records contain the actual and promised shipping dates for each order. Angie used a spreadsheet to determine the number of shipments that were made after the promised shipment dates. The number of late shipments from the 50 sampled records was then reported. These data are shown in Table 3. Finally, to monitor the thickness of the I-beam produced at the plant, Angie randomly selected six I-beams every day for 30 days and had each sampled beam measured. The thickness of each beam, in inches, was recorded. All of the data collected
by Angie are contained in the file Izbar. She wants to use the information she has collected to construct and analyze the appropriate control charts for the plant's production processes. She intends to present this information at the next manager's meeting on Monday morning. Required Tasks:
a. Use the data that Angie has collected to develop and analyze the appropriate control charts for this process. Be sure to label each control chart carefully and also to identify the type of control chart used.
b. Do the processes analyzed appear to be in control? Why or why not? What would you suggest that Angie do?
c. Does Angie need to continue to monitor her processes on a regular basis? How should she do this? Also, are there other variables that might be of interest to her in monitoring the plant's performance? If so, what do you think they might be?