The many different ways of using control charts in both service and manufacturing applications may be summarized under five major headings. These five categories are arranged in order of increasing sophistication below.



The first of these is that of Report Card Charts. Report Card Charts are charts kept for the files. They may be occasionally used for information about how things are going, or for verification that something has or has not occurred, but they are not used in real time for operating or improving the processes and systems present. This is a valid but weak usage of control charts.

The next category consists of Process Adjustment Charts. Some product characteristic may be plotted on a control chart and used in a feedback loop for making process adjustments, or some input characteristic may be tracked and used in a feed-forward loop for the same purpose. In many cases these Process Adjustment Charts will result in substantially more consistent operations than was the case prior to the use of control charts. (This assumes that one will know how to properly adjust the process. In some cases such knowledge can only be gained by some of the following uses of control charts.) However, once this initial improvement has been achieved, Process Adjustment Charts simply strive to preserve the new status quo. The potential for dynamic and continual improvement is missing from this usage of the charts. Unfortunately, this seems to be the only usage considered in most of the articles recently published in the journals.



The third category is Process Trial Charts. These are charts used to analyze the data from simple experiments performed upon the process. This short-term usage of control charts is a simple and easy-to- understand alternative to the use of ANOVA and other statistical techniques. This usage is often found in
conjunction with the next category.

read this article on SPC press

Typically on the left vertical axis is frequency of occurrence, but it can alternatively represent cost or other important unit of measure. The right vertical axis is the cumulative percentage of the total number of occurrences, total cost, or total of the particular unit of measure. The purpose is to highlight the most important among a (typically large) set of factors. In quality control, the Pareto chart often represents the most common sources of defects, the highest occurring type of defect, or the most frequent reasons for customer complaints, etc. See this help file how to use our tool.

Online pareto chart

Quality Control

Two small software vendors this week released business intelligence product upgrades that will allow manufacturers to more accurately and rapidly assess the cost and quality of their products.

SigmaQuest Inc., a provider of on-demand product quality analysis tools, released version 6.1 of its flagship SigmaSure product, which adds several new features, including support for identifying potentially costly, low-quality “maverick” products before they are shipped.



At the same time, aPriori, a provider of cost management analysis software, delivered version 5.5 of its self-named tool, which, among other things, allows manufacturers to compute the cost of a single component manufactured in multiple internal or supplier plants.

The most significant new feature in the 6.1 release of SigmaQuest’s SigmaSure is support for analysis of maverick parts and products, a capability that is increasingly important to manufacturers of electronics components, SigmaQuest’s largest customer base. A maverick part is defined by the JEDEC Solid State Technology Association as an “atypical product that exhibits anomalistic characteristics causing higher-than-normal levels of failure in the end-user application.”



Maverick parts, for example, may fall within prescribed functional test parameters but still fail often in the field, leading to costly product returns. Many electronic equipment OEMs, said SigmaQuest CEO Nader Fathi, have begun to require component suppliers to certify that they have analyzed part lots for their potential to exhibit maverick behavior.

“Just looking at product yields is not good enough to determine if products will behave correctly,” Fathi told Managing Automation today.

Read more

Pie charts

• Bar charts
• Run Charts
• Radar Charts
• Scatter Plots
• Histograms
• Pareto Charts
• Normal Test Plots
• Process Capability Calculations
• Control Charts
• Relations Diagram
• Pathway
• Affinity Diagrams
• Brainstorms
• Building Consensus
• Cause and Effect Diagrams
• Flowcharts
• Force Field Diagrams
• Tree Diagrams

Online tools like Pareto chart, histogram and scatter diagram. Online and free