Statistical Quality Control. Bhisham C. Gupta
Poor training Non‐standard work Lack of job aids Poor communication
2.4.2.3 The 5S Method
The tool known as 5S is defined as a physical methodology that leads to a workplace that is clean, uncluttered, safe, and well organized, resulting in reduced waste and increased productivity. The tool helps create a quality work environment, both physical and mentally.
The 5S philosophy applies in any work area suited for visual control and Lean production. 5S is derived from the following Japanese terms that refer to creating such a workplace:
Seiri: To separate needed tools, parts, and instructions from unneeded material and to remove the unneeded ones.
Seiton: To neatly arrange and identify parts and tools for ease of use.
Seiso: To conduct a cleanup campaign.
Seiketsu: To conduct seiri, seiton, and seiso daily to maintain a workplace in perfect condition.
Shitsuke: To form the habit of always following the first four S’s.
Table 2.3 lists the Japanese terms and the English translations of the 5S methods.
Benefits to be derived from implementing a 5S program include:
Improved safety
Higher equipment availability
Lower defect rates
Reduced costs
Increase production agility and flexibilityTable 2.3 The 5S methods.JapaneseTranslatedEnglishDefinitionSeiriOrganizeSortEliminate whatever is not needed by separating needed tools, parts, and instructions from unneeded material.SeitonOrderlinessSet in orderOrganize whatever remains by neatly arranging and identifying parts and tools for ease of use.SeisoCleanlinessShineClean the work area by conducting a cleanup campaignSeiketsuStandardizeStandardizeSchedule regular cleaning and maintenance by conducting seiri, seiton, and seiso daily.ShitsukeDisciplineSustainMake 5S a way of life by forming the habit of always following the first four S’s.
Improved employee morale
Better asset utilization
Enhanced enterprise image to customers, suppliers, employees, and management
2.4.2.4 Value‐Stream Mapping
A value‐stream map is a high‐level process map that captures the steps of a process from the time a customer orders a product to the time it is delivered. The map also shows how information, work, and materials flow through the process. The team starts with a current state map to document the process as it exists now. This map is used to identify and quantify waste and to highlight areas that can be improved.
After the current state is well understood, the team builds a future‐state map that eliminates unnecessary steps or other sources of waste that have been identified. This future‐state map gives the team a blueprint for improvement.
2.4.2.5 Mistake‐Proofing
Mistake‐proofing is also known by its Japanese name, pokayoke. The technique is always handy, but it is especially useful in preventing defects when they are rare or when errors are random and non‐systematic.
There is a classic definition of mistake‐proofing: the complete elimination of errors. But over the years, mistake‐proofing has been expanded to include controls or warnings. With this version, having a machine shut down after a mistake is made, or a light or alarm sound when an error occurs, is considered mistake‐proofing. Checklists also fall into the control category. All of these are effective if the warning is heeded or the checklist is adhered to. But the gold standard, of course, is to have a design in which the mistake does not occur in the first place.
A classic example of mistake‐proofing is diesel and unleaded fuel nozzles at gas stations. You can’t put diesel fuel in your unleaded gas tank; the nozzles just won’t fit. This is an example of the elimination of a defect by design.
2.4.2.6 Quick Changeover
The quick‐changeover tool can be used to reduce or eliminate waiting waste and increase machine availability. In manufacturing, maintenance must change over a line when it is switched from making one product to the next. If a manufacturing plant can achieve shorter changeover times, it can run its production line with smaller batches. This reduces inventory waste and allows the plant to match its production output to customer demand. If a plant spends more time producing and less time changing over, it can increase its capacity.
Dr. Shigeo Shingo developed quick‐changeover techniques while working with an auto manufacturer. He defined changeover time as the total time from the last unit of production to the first unit of good production at full speed. To dramatically reduce changeover time, teams convert internal work to external work.
Internal work consists of all the tasks performed while the line is shut down. External tasks are performed either before the line is shut down or after the line is up and running again. By performing a detailed work breakdown, the team can convert internal tasks to external task: doing things ahead of time, or after the fact, so that the actual downtime and internal work are minimal.
Unlike other tools used in Lean, quick changeover may require some significant capital investment, such as specialty tools and fasteners designed to minimize downtime. The goal is to re‐design, re‐engineer, and re‐tool.
2.5 Six Sigma Benefits and Criticism
Motorola, along with the early adopters of the Six Sigma methodology (General Electric, Allied Signal, and Honeywell), have all reported remarkable financial benefits. From its inception in 1986 until 2001, Six Sigma saved Motorola $16.1 billion. GE, after investing $1.6 billion in the program, delivered a $4.4 billion savings in a three‐year period. Allied Signal and Honeywell each attributed $500 million in savings to Six Sigma efforts in 1998 alone. In all, Six Sigma delivered savings on the order of 1.2 to 4.5% of company revenue [2].
The power of Six Sigma was also recognized by the US government. After implementing Six Sigma methods in 2006, the US Army claimed savings of $19.1 billion as of April 2011 [3]. In 2012, the White House praised the contributions of Six Sigma along with Lean methodology in eliminating unnecessary review steps for air and water permitting [4].
Despite these well‐publicized benefits, not everyone has a favorable view of Six Sigma practices, and some doubt its efficacy. In 2007, a study conducted by Qual Pro, a consulting firm and proponent of a competing quality improvement system, reported that 53 of 58 companies that use Six Sigma have trailed the S&P 500 ever since they implemented it [5]. Of course, there is no proof of a causal relationship between Six Sigma implementation and poor financial results. In fact, it could be argued that companies adopting Six Sigma had a compelling quality or financial reason to do so and would have fared even worse if they hadn’t adopted the program.
Others have argued that the rigor of the Six Sigma process can stymie innovation. The Six Sigma approach that is so successful in tackling problems in existing processes may have the opposite effect in research and development organizations. In these cases, the systematic, highly ordered approach may thwart the creativity necessary for cutting‐edge advances.
Another perceived drawback of Six Sigma is its heavy training burden. In an enterprise‐wide deployment, employees at all levels of the organization must be trained to some degree, with Green and Black