Built in Quality

7 quality tools

Description

The 7 quality tools present complex or abstract statistical information in a simple pictorial form. They can play a crucial part in the drive to reduce costs, improve quality and safety and enhance productivity.

When should it be used?

The 7 quality tools should be used to identify concerns, record and analyse results and to define an appropriate course of action.

What will you get?

Flowcharts and check sheets provide a way of identifying areas for improvement. The other tools provide ways of deepening the understanding of what can be improved and will analyse the best methods for implementing the improvement. When all the tools have been applied they form a strong basis for selecting a solution.

The process

There are two sets of tools within this technique:

1. Identification - these tools allow us to identify areas for improvement.
2. Analysis - this set of tools allows identification and analysis.

Identification

Flowcharts

Flowcharts can be created for any process or operation to indicate how work happens.

Check sheets

Check sheets are used for recording and analysing results, a simple form in which to note observations. Check sheets act as the starting point of the analysis process and can help to structure data prior to analysis.

Pareto analysis

This is the 80:20 rule discussed on page 30.

Cause and effect diagrams

Cause and effect diagrams are used to list probable causes and rate their importance. See page 43 for further detail.

Analysis

Histograms

Histograms form a graph in which a vast amount of information can be communicated at a glance. They provide ease of understanding for all levels of the workforce.

Statistical process control

Statistical process control recognises that manufacturing processes naturally vary. This method takes process data, using it to describe the process itself rather than individual activities to spot unusual variables.

Scatter plots

Scatter plots provide a quick easy way of identifying if two variables are related. The idea is to note points and see if the cause and effect are related, rather than plotting a graph to establish a direct relationship.

Poka Yoke

Description

Error-proofing refers to the implementation of fail-safe mechanisms to prevent a process from producing defects. This activity is also know by the Japanese term poka-yoke, from poka (inadvertent errors) and yokeru (to avoid).

When is it used?

The philosophy behind error proofing is that it is not acceptable to make even a very small number of defects, and the only way to achieve this goal is to prevent them from happening in the first place. In essence, errorproofing becomes a method 100% inspection at the source rather than down the line, after additional value has been added (wasted).

Achieving extremely high levels of process capability requires this type of focus on prevention rather than detection. You may not realise it, but you probably encounter many examples of error-proofing in your every-day life, as outlined below: Examples From Every-Day:

. When you close a computer file, the operating system may ask you if you want to save your work first to prevent losing it inadvertently.
. Childproof caps on medicine bottles keep children from taking medication that could be harmful.
. Color-coding of components that otherwise look similar.

What will you get?

There are three basic categories of error-proofing:

. At the simplest level are WARNINGS that provide quick feedback of a potential problem, like a smoke-alarm or the warning lights on your car instrument panel.
. Automatic SHUTDOWN controls force the problem to be corrected before resuming production, such as the vehicle electrical test mentioned above.
. AUTOCORRECTION controls provide an integrated test-feedback-repair loop, such as the spell-checker in a word processing program.

The Process

Error-proofing is an excellent activity to involve the workforce in continuous improvement. Many poka-yoke ideas relieve stress from operators by eliminating the need to concentrate on mundane activities and by providing more capable tools to get the job done right consistently. And remember, operations that require more finesse, adjustment, judgement are not just a quality risk, they also take more time, and are therefore more wasteful than they could be in terms of productivity and quality. The first step in applying error-proofing principles is to identify all of the possible errors that can be generated by an operation. A cause and effect diagram may be a useful tool to organise your efforts. After identifying the potential errors, involve the workforce in Brainstorming to generate ideas to provide Warning, Shutdown, or Autocorrection to the process.