Statistical analysis and process capability determination of an industrial process

Quality means suitability for use and it is inversely proportional to variability of product, service, people, processes, and environment. However, it is the dynamic state that is associated with each of the above and that meets or exceeds expectations of a customer. Quality improvement is therefore the progressive reduction of variability. The gradual reduction of process and product variability can be done by successive determination and removal of the causes responsible for the variability. Determination of process capability is not hard, but it is frequently overlooked. It should be done first in any quality improvement program. It must be repeated on a periodic basis to ensure that the process stay fit to produce product of desired specification. If the process is incapable, then it is management´s responsibility to either improve the process or accept poor quality product. The workers cannot be held responsible for failure to meet standards, if they do not have any means to achieve those specifications. Process capability of a certain process is determined by collecting a set of data sample of an output product specification from the process that is under optimal control. Then calculating the upper and lower natural tolerance limits that is within 6σ (6-sigma, σ=standard deviation) spread in the distribution. In other words collected data samples should reveal that the product specification is within 6σ distribution limits, If μ (mu) is the target specification, then the 99.73% of the product produced by the process under investigation must fall within μ+3σ and μ-3σ. If so, the process is said to be capable. If it is not within these two limits, the process is not quite profitable and is a candidate for improvement. This research paper analyses and outlines the procedure for the determination of process capability of an industrial process