Determining Process Capability With Six Sigma

The capability of any given process, which in other words may be termed as Process Capability or PC relates to the frequency or occurrence with which a process, such as an assembly-line production that will give the output (marketable product) strictly in accordance to the specification given by a client or a customer. Thus, PC or process capability may also be considered the opposite of a process’s fault ratio. While it is agreed that even the best of processes are liable to create some amount of defect, or variation in its output, it is essential for a process to have adequate capability to produce maximum amount of products that can meet the customer’s specifications. Otherwise, all the products developed may be rejected by the customer.

Understanding Six Sigma Process Capability

Six Sigma incidentally, is a well established business management strategy that endeavors to improve upon the average output quality of a process, or the process capability. This is done by putting more stress on eliminating the faults by way of locating, and very often by removing these unwanted variables. At for the sigma part of it, this refers to the number of variations that may occur between the mean and the customer’s given specifications. A six sigma process, therefore, is a process that can have six typical variations so far as the process mean and the customer specification is concerned. As may be expected, this will result in a small number of items that will fail to satisfy customer requirements. Conceived initially by Bill Smith of the Motorola Corporation in 1986, it is a main stay with most Fortune 500 American companies.

Six sigma system of process capability or control is basically involved in establishing the Upper Specification Limit (USL) and Lower Specification Limit (LSL) of a given output. These limits are generally based on the requirement of any particular customer, and so need not necessarily imply that the process is capable of producing output only within those given ranges.

However, when the values have been finally established, experts proficient in Six Sigma start creating averages for the actual production by using real time data. The standard deviation is then determined when all the variables have been duly processed and analyzed. After that, one can easily determine if the process is capable of meeting or failing customer requirements by using the standard capability index. Despite its weak points, it is still regarded as the most reliable system for checking process capability in many industries. This method of ensuring process capability is globally recognized today.