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Quality Improvement Programs

Quality Improvement Programs and Tools
  • Control charts
  • Lot sampling
  • Process capability
  • Value Analysis (VA)
  • were first used extensively in World War II in response to the need for tremendous volumes of high quality, lower cost materials. More recently, Quality Circles, TQM, and Kaizen have demonstrated the power of team-base process improvement. Process Capability and Design of Experiments (DOE) have come to the fore in Six Sigma. 
  • Control Charts
  • Statistical Quality Control (SQC) or Statistical Process Control (SPC) for repetitive, high volume production began in the 1930's when Shewhart developed control charts. Small production samples were measured periodically to monitor quality. Sample mean (Xbar) and range (R) charts were used to detect when a process was going out of "economic control."
The causes of variations that exceed the upper and lower control limits (UCL and LCL respectively), such as at "A", must be eliminated in order to bring the process back into statistical control.

Deming PDCA


The Deming / Shewhart Cycle was especially useful in solving these quality problems. The PDCA Circle denotes continuous improvement by repeating the basic cycle of
  • Plan
  • Get the data
  • Analyze the problem
  • Plan the solution
  • "Do" It
  • Check -- Measure the change
  • Act -- Modify as needed
as long as significant improvements are obtained.


Since 1948, engineers at Carnegie Tech (now Carnegie Mellon University) have been trained to apply the Carnegie problem solving methodology in design. This methodology parallels the Deming PDCA cycle with the addition of an initial step to "Define the Problem."

In the last 20 years, many companies have adopted similar problem-solving models -- often with 8-10 steps or more. Special attention is given to solving process problems -- problems that occur repetitively. Process improvement models add such steps as assigning process owners, forming teams, and establishing process measures.


Juran

Juran focused on quality control with the "trilogy"
  • quality planning
  • quality control
  • quality improvement.
An SPC representation of the trilogy is used in the figure at the right. A spec is developed -- usually with a ± tolerance. A control chart is used to get the process under control. As special causes are removed to improve the process , variation is reduced. These are the basic steps in Six Sigma process improvement. When the total quality management movement (TQM) gained prominence in the 1980's, the product planning step was expanded to include a broader evaluation of customer needs (similar to VA and QFD ).
Value Analysis Teams


In Value Analysis, developed by Larry Miles at GE during WWII, multi-functional teams (design, production engineering, purchasing, quality) use a formalized process to identify alternative materials, manufacturing processes, and designs to improve function while reducing costs. The "Job Plan" for a Value Analysis study of a specific product or process has the following format
  • Pre-Study
  • Collect customer data
  • Collect product and process data
  • Build product and process models
  • Form the multi-functional team
  • Study
  • Information Phase -- analyze data
  • Function Analysis Phase -- identify and cost functions
  • Creative Phase -- brainstorm ideas
  • Evaluation Phase -- rank then develop ideas
  • Development Phase -- quantify benefits and plan actions
  • Presentation -- make oral report and prepare written reports
  • Post-Study (added more recently)
  • Complete changes
  • Implement changes
  • Monitor changes

The very structured function diagramming and costing techniques provide data for quantified (cost and value) decision-making. The whole VA process is a precursor of the MAI -- Measure, Analyze, Improve -- in the broad based Six Sigma improvement process. Six Sigma adds the C or Control step. The brainstorming methodology in VA has been widely emulated in process improvement teams. Ideas are generated in a non-critical, free-flowing process. Then, ideas are grouped using affinity diagramming techniques and refined as needed for practicality. Teams


Japanese Quality Circles demonstrated the effectiveness of worker teams in identifying and solving process problems in their work area. However, most serious quality problems in non-manufacturing (as well as manufacturing) organizations arise in activities that involve more than one department / function. Quality Circles has evolved into Kaizen, which utilizes multi-functional worker and production engineering teams to improve quality and productivity in a given process. The teams use TQM techniques in implementing "Lean" manufacturing methods.

TQM


Total Quality Management (TQM) emphasized using multi-functional teams (professional staff and workers from all departments involved) to solve problems. The teams were trained to use basic statistical tools to collect and analyze data.
  • Check sheets
  • Pareto diagrams
  • Histograms
  • Run charts
  • Flow charts
  • Cause and effect diagrams
  • Force field analysis
  • Scatter diagrams
Flow charts or process maps were used to visualize the flow of product or documents through a series of process steps. The predominant goal of Process Improvement Teams was to eliminate the non-value adding steps and to resolve quality problems in order to reduce the (cycle) time needed to complete the process. IS  ISO9000 was developed as a standard for business quality systems. To be certified, businesses needed to document their quality system and insure adherence to it with reviews and audits. A key element was the identification of non-conformances and a Corrective Action System to prevent reoccurrences. Specific quality improvement methodologies were not prescribed. The automotive industry adopted the QS9000 standard for their suppliers to require the use of specific practices in quality planning and in production operations.
  • Advanced Product Quality Plans
  • Design / Process Failure Mode and Effects Analysis (FMEA)
  • Production Part Approval Process
  • Control Plans (for production)
  • Measurement Systems Analysis
  • The Juran methodology was central to maintaining control of special product and process characteristics (CTQs).
  • Design of Experiments (DOE)
Six Sigma process improvement emphasizes getting quantitative data on the effect of key variables in production, service, or administrative processes. Many process improvement efforts go astray because people assume they know all of the key variables -- key variables and especially interactions between variables are not always obvious. Simple statistical data gathering or testing can be used to verify or determine these key variables.

In DOE, a series of experiments (tests) are conducted to determine the relative importance of the key variables and to assist in selecting optimum operating values. The number of variables is usually limited so that the time, effort, and cost of testing is not excessive. After the array of tests (experiments) are complete, graphical techniques -- such as at the right -- can be used to illustrate the results. DOE is especially useful in simplifying the improvement process for complex technical and administrative processes.


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