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James Odom

Six Sigma

The Power of Observation, Part 2

Observation is a powerful technique that can be used to help understand manufacturing problems.

Published: Wednesday, July 8, 2009 - 10:34

In “The Power of Observation—Part 1,” we learned that a good portion of problem solving should be devoted to a thorough understanding of what’s going on before any corrective action steps are taken.

In many cases, too much time is spent on proposing various solutions before the problem has been correctly defined. Observation is a powerful technique that can be used to help understand problems.

At the end of the first part of this article, I promised to share some observational tools and techniques that can help you better understand processes. Here they are:

Process mapping or value stream mapping (See figure 1.). Map the process while walking through it from beginning to end. Look for areas where problems could occur, i.e., scrap, lack of process control, lack of method, etc. Visit the area on different shifts. Are differences in method observed, differences in defects, and so on? Are two pieces of equipment making the same part? If so, can a comparison be made? As you walk the process, think about the 6Ms: machine, material, method, man, measurement, and Mother Nature. Look to see if any of them are controlled, vary (create noise in the system), or are specified by procedure, work instruction, etc.

Concentration diagrams (See Figure 2). A concentration diagram is a drawing or schematic of a part used to locate where defects are occurring. Defective parts are collected, and the defect location is marked on the drawing. If a nonrandom pattern forms or defects are concentrated in a particular location, and a significant number of parts have been observed, it can provide a clue to the cause of the problem. In the diagram, shown in Figure 2, a number of nonconformances occur in a concentrated area. Further investigation would center on what process areas come in contact with this part of the product.

Standardize work. Standardized work is a tool for maintaining productivity, quality, and safety at high levels. It's defined as work in which the sequence of job elements has been efficiently organized and is repeatedly followed by all employees. What is the method for performing a job function? Has it been documented? Are employees following the method? Can it be improved? Do methods differ between operators with high defect rates versus those with low defect rates?

5S and housekeeping—a place for everything and everything in its place (See Figure 3). 5S is a structured process for maintaining an efficient and effective workplace. The 5S approach is a set of strategies and techniques that provide a standardized method to housekeeping. The strategies are based on:

  • Sorting needed items from those that aren’t
  • Straightening the remaining items in an organized manner
  • Scrubbing to get and keep them clean
  • Standardizing the above process
  • Sustaining the improvements.

 

A cluttered area isn't only visually unpleasant, but also leads to many undiscovered problems that drag on month after month. Clean equipment and work areas improve safety and can help prevent problems associated with machine oil loss and other related failures.

Visual controls. Visual controls are used to transform a factory into one that is self-explaining, self-ordering, self-regulating, and self-improving. A visual system answers the questions, "where, what, when, who, how many, and how" with visual answers. Using visual controls makes it very easy to see if something is amiss.

Process failure mode and effects analysis (PFMEA). After the process map is complete, walk the process again and look for potential failure modes. These are potential problems that can create defects, scrap, or other customer dissatisfaction. After identifying the potential failure modes, corrective actions can be implemented to eliminate or reduce the problems.

Is/Is not analysis (See Table below). This includes a matrix in which a number of questions are asked concerning a problem and contrasts are made between those parts that have the problem and those that you would expect to have the problem, but don’t.

 

Is

Is Not

Contrast

More Info Needed?

What

What is the specific
object that has to defect?

 

What is the specific
defect?

What similar objects could have the defect
but do not?

 

What other defects could be observed but are not?

 

 

Where

Geographically?


Physically on the part?

Where could the defect  have occurred but didn't?

 

 

When

When was the defect first observed? 

 

When since then? 

 

When in the product life cycle?

When could the defect have occurred but didn't?

 

 

Size

How many objects have the defect? 

 

How many defects per object?

 

Size of defect?

 

Trend?

 

 

 

 

What else makes it work?

Here are some additional pointers when using the power of observation to understand manufacturing problems:

Use graphs and charts to present facts in visual form. Graphs and charts can send a very powerful message to people. The use of images makes a more vivid impact than just numbers. Graphs also have the ability to strengthen inferences about your observation based on the type of graph, color used, etc. Remember, a picture is worth a 1,000 words.

Communicate visually. Visual methods can be used to communicate the gap between the standard and actual. Make a comparison between the standard and the actual to identify differences that may have caused the nonconformance to occur.

Try to make things simple. Anyone should be able to walk up to the process and understand what you are trying to do. If they can’t, you need to look at the workstation layout and find ways to improve product flow.

Examine the correction one more time. Once the corrective action is in place, put yourself back in the circle and observe if the corrective action is working the way you intended. This is important because sometimes the solution can cause other problems to occur.

Note: This article was first published in AIAG's June 2009 Quality, Standards and Tools newsletter.

For an excellent example of many of these techniques in use at a real manufacturing facility, watch this Quality Roadshow video by Mike Micklewright.
--Editor
 

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About The Author

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James Odom

James L. Odom is a lean Six Sigma Master Black Belt with more than 30 years of experience in quality engineering. He's a certified quality engineer and a senior member of ASQ. In 2005, Odom received the ASQ Automotive Division’s Quality Professional of the Year Award. He is based in Cortland, Ohio.