How to Explain and Understand Process Capability

Have you tried to explain the concept of process capability to someone who then looks at you like you have two heads? Try using the following analogy to explain the subject more easily. Driving in a Construction Area Imagine you are driving on a highway that is undergoing construction. The width of your vehicle –…


Getting the Most out of a Capability Analysis

The process capability indices Pp and Cp describe how closely a process can operate within its specification limits. Many articles describe the difference between Pp and Cp simply: one is short term, one is long term. Moving beyond such a description, this article focuses on the untapped power of capability analysis and shows you how…


Specification Limits: Proceed with Caution

It’s natural for a manufacturing group to be concerned with a product’s specification limits – the upper and lower limits imposed on the process. Specification limits are sometimes designated by the producer, definitions of quality or, most frequently, a customer, in an attempt to narrow the distribution of a product’s properties. Unfortunately, to keep a…


What Is a Stable Process?

Process stability is one of the most important concepts of the Six Sigma methodology, or any quality improvement methodology for that matter. Stability involves achieving consistent and, ultimately, higher process yields through the application of an improvement methodology. Does a process need to be stable in order for a black belt to improve it? Try…