The capability involves the difference between mean added to 4SD and mean 4SD. In this case, the capability index measures the relative variability to the tolerance band. Capability indices enable the company to identify its capability to produce products that are within its customers’ specification limit. In this case, USL is 9.00V, while LSL is 0.25V, mean, and standard deviation of 30 manufactured units are 9.10V and 0.06V, respectively.
The role capability is to bring down manufacturing or processing operations with zero defects by improving their capability indices. The defect level in USL and LSL will be as shown in the following figure.
Cpk = min [x̅- LSL/3s, USL-x̅/3s] =min (Z1 Zu)
= min (9.10-9.00/30.06, 9.10-0.25/30.06
=min (0.6, 48.61)
=-0.007 is the minimum value
48.61 is the maximum value
Yes, it is safe for the company to proceed with the production because the USL and LSL show the capability of the company to meet customers’ satisfaction based on their needs. The negative value is minimal, and it indicates that the company can meet specifications in its processes. With 48.61 as its Cpk value, it shows that the company’s processes are centered between its specifications limit. Therefore, the company should continue with the process because capability analysis indicates that it is consistent, and it is relative to its customer requirements concerning specification limits of the products’ parameters.