Quality Tools for Quality Auditors

As auditors, we see a variety of quality tools used within a quality management system. Since many of these tools are named after a person, use a Japanese word, or refer to an acronym or abbreviation, some auditors may not immediately recognize them. A brief description is provided below for some of the common tools.

Shewhart Cycle: Walter Shewhart defined the Plan-Do-Check-Act (PDCA) cycle as a helpful tool for process improvement. The Shewhart cycle is often called the Deming cycle since W. Edwards Deming proposed it for process improvement in Japan (although he gave credit to Shewhart). Deming used Plan-Do-Study-Act (PDSA) instead of PDCA.

Ishikawa Diagram: Kaoru Ishikawa developed a Cause and Effect diagram for determining the potential causes of an undesirable event. The diagram is often called a Fishbone diagram since the slanted lines representing the potential causes resemble the bones of a fish. The potential causes are grouped as Machine, Method, Material, Manpower, Measurement, and Environment. The diagram may also be referred to as a “4M” diagram (when only using Machine, Method, Material, and Manpower) or “5M & E” when all the cause categories are considered.

The purpose of the diagram is to arrive at a few key sources that contribute most significantly to the problem being examined. These sources are then targeted for improvement. The diagram also illustrates the relationships among the wide variety of possible contributors to the effect.

Pareto Principle: When Joseph Juran was looking for a short name to apply to the phenomenon of the “vital few” and “trivial many”, he referred to it as Pareto’s principle of unequal distribution. Vilfredo Pareto was an economist  that applied the principle to income and wealth. Juran expanded it to a universal rule that, in most cases, a few problem categories (about 20%) will present the most opportunities for improvement (about 80%).

As a result, the Pareto Principle is also called the “80/20 Rule”, meaning that in anything a few (20 percent) are vital and many (80 percent) are trivial. A Pareto Chart is a column graph that prioritizes problems so the major ones can be identified.

Likert Scales: Renis Likert devised a measurement method, called Likert Scales, used in attitude surveys. They allowed answers ranging from “strongly disagree” to “strongly agree.” A Likert scale measures the extent to which a respondent agrees or disagrees with a statement.

Customer satisfaction surveys use rating scales and the most common scale for agreement is 1=strongly disagree, 2=disagree, 3=undecided, 4=agree, and 5=strongly agree.  Other survey statements may relate to frequency (1=never, 2=seldom, 3=sometimes, 4=often, 5=always), importance (1=unimportant, 2=of little importance, 3=moderately important, 4=important, 5=very important), and quality (1=very poor, 2=poor, 3=average, 4=good, 5=very good).

Kanban: Kanban is the Japanese word meaning Kan = card, Ban = signal, or “signboard”. It is a key tool in a Just-In-Time system and provides a visual sign to “pull” more work from one process to the next. It maintains an orderly and efficient flow of materials throughout the entire manufacturing process. It is usually a printed card with specific information such as part name, description, quantity, location, supplier, delivery, etc.

Every part and assembly that moves through the production sequence has an accompanying kanban. “Production instruction” kanban circulate inside each process. “Withdrawal” kanban circulate between processes. Processes use a “withdrawal” kanban to “buy” parts from the preceding process to replace the parts they used. And, the processes each array the parts they have made for the following process to withdraw when necessary.

Kaizen: Kaizen is a Japanese word meaning continuous improvement. It is taken from Kai = change and Zen = good. A Kaizen strategy involves everyone in an organization working together to make improvements. It is a culture of sustained continuous improvement focusing on eliminating waste in all systems and processes of an organization. Involved leaders guide people to continuously improve their ability to meet expectations of high quality, low cost, and on-time delivery.

Kaizen, Lean, and Six Sigma are all improvement tools. The logic of Kaizen is that breakthroughs result not from massive reorganizations or large-scale investment projects, but from the cumulative effects of successive incremental improvements. Although an oversimplification, Kaizen may focus on tactical, quick fixes; Lean on eliminating non-value-added activities and shortening cycle times; Six Sigma on reducing process variation and improving process capability.

Hoshin Kanri: Hoshin Kanri is a systems approach to the management of change in critical business processes using a step-by-step planning, implementation, and review process. The word Hoshin can be broken into two parts: Ho = direction and Shin = needle. So, the word Hoshin translates into direction needle or compass. The word Kanri can also be broken into two parts: Kan = control or channeling and Ri = reason or logic. Therefore, Hoshin Kanri refers to the management and control of an organization’s compass or focus. The most popular English translation of Hoshin Kanri is Policy Deployment or Management by Objectives.

5S: 5S is a methodology for organizing, cleaning, developing, and sustaining a productive work environment. The five Japanese “S” words for organizing the workplace are Seiko (proper arrangement), Seiton (orderliness), Seiketso (personal cleanliness),Seiso (cleanup), and Shitsuke (personal discipline). 5S deals  with issues such as: Space crowded with parts and tools; Unneeded items stacked between workers; Excess inventory on the floor; Excess items and machines making it difficult to improve process flow; Dirty and cluttered equipment; and Equipment and tools difficult to find.

Pokayoke: Shigeo Shingo has been credited with creating and formalizing the zero quality control approach that relies heavily on “pokayoke”, the Japanese word for mistake-proofing. Shingo stated, “The causes of defects lie in worker errors, and defects are the results of neglecting those errors. It follows that mistakes will not turn into defects if worker errors are discovered and eliminated beforehand.” In its simplest form, a pokayoke (pronounced POH-kah YOH-kay) is a device or piece of equipment that provides mistake-proofing. It does not allow a part to proceed unless the error is removed. Pokayoke also relieves people of the need for constant vigilance, as it automatically stops any part that may have slipped through, even if the person is tired. For more information, see the separate article on Pokayoke in this newsletter.