What is it: Patterns are helpful in solving quality-related problems too and one of the best tools for displaying a pattern is the defect concentration diagram. Defect concentration diagrams are the embodiment of the old adage: "A picture is worth a thousand words." A defect concentration diagram is a visual data display tool that literally shows where defects or problems are concentrated. Seeing the pattern of defects can often be the catalyst to get to the root cause(s) of a problem and ensure the problem is solved for good. Since concentration diagrams literally paint a picture of the problem, they are one of the most powerful data collection/display/analysis tools we have. Unfortunately, they are one of the most underutilized tools as well.
In an electronics assembly factory, the inspector at the end of a production line of printed circuit board assemblies would have a picture or drawing of the printed circuit board showing all the various components etc. When they found a fault, they would simply mark the faulty component on the drawing, creating over a week a simple analysis of where the faults were occurring. Their great advantage is that the data becomes easy to collect and then needs little or no analysis - the diagrams are almost self analysing.
What is it used for: To show the location of errors or defects.
Why use it: To determine were the faults are occuring on the production part.
Where to use it: Proceeding any operation.
When to use it: For either capturing or displaying defects data that can be segregated by location. This can show which location to focus efforts on.
How to use it: Concentration diagrams are incredibly easy to use; data collection and data analysis are both a snap and are done in just one step, not two separate steps. There is no need to develop forms to collect data; depending on the scope of the study, a print of the part, a map of the area or a copy of a procedural form can be used to collect the data.
Step 1 - Define the fault or faults (or whatever) being investigated.
Step 2 - Make a map, drawing, or picture.
Step 3 - Mark on the diagram each time a fault (or whatever) occurs and where it occurs.
Step 4 - After a sufficient period of time analyse it to identify where the faults occur. Perhaps simply when a pattern starts to develop, that it can be identified.
Important Notes: This can be used for products, processes, or even plant locations.