Dean Door Case Study

1.) Although all observations from all samples fall within the upper and lower specifications, the process is out of control at a 3 sigma standard. Based on the process capability ratio at 3 sigma (1.0) the current process index of .966 barely does not meet a 3 sigma standard. The X bar chart indicated the process was out of control at 3 sigma. Several samples bell below the lower control limit and that seems to be the primary problem with the process. The X bar chart demonstrated some sudden changes and inconsistencies in the cuts from one sample to another. The R-chart shows no process control problems, however there are wider variations early in the sampling but it seems that they are reduced later in the sample. The chart exhibits an increasing trend, which may be due to a new group of operators gaining experience on the job or maintenance of the equipment is improving over time. The process capability is 1.232. The process capability indexes shows that the process capabilities for the company are not good. In order to eliminate some of the problems they are having they could use control charts to control quality.

2.) After the recommendations were implemented, the process improved to a 3 sigma standard with a process capability index of 1.13 which exceeds the 3 sigma standard of 1.0. The process is out of control at 3 sigma based both on the X bar and R-charts. A trend toward cutting longer than 30 inches surfaced in the X bar charts during the later samples, so the company should continue to monitor that situation. The company should investigate the operating skill of the additional workers and take precautions (training plan) to ensure that the workers carry out consistent production. The R chart shows a good trend in reduced variations of the cuts, so this is very positive. Looking at the post recommendations charts by shift, no shifts are out of process control. The process capability index is 1.213