What are 7 QC Tools During Quality Transformation?

“Every action is an opportunity to improve”

Mark Graban

They are called basic because they’re easy to use and don’t need a master’s degree in statistics and could be implemented by any person with very basic training in statistics. The 7 QC tools are basic instruments to improve the process & product quality. We use these tools to examine the production process, identify the key issues, control fluctuations in product quality, and give solutions to avoid future defects.

7 QC tools apply to any industry in the VUCA World. If you know how to use the 7 basic tools, then it will provide you with a big help with solving the problems you face at work regularly.

Quality is an essential feature for successful businesses to validate. Six Sigma projects taken on by those who completed an online Six Sigma training focus on improving processes to ensure better quality. By effectively using the 7 QC tools with examples we can maintain the consistency of the services & products that are producing.

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The QC Tools 7

• Cause-and-effect diagram (fishbone or Ishikawa diagram)

• Flow Chart 

• Check Sheet (Tally Sheet)

• Pareto chart (80/20 Rule)

• Histogram

• Control chart (Shewhart Chart)

• Scatter diagram

1. Cause-and-effect Diagram (Ishikawa or Fishbone Diagram)

 An Ishikawa diagram is also famous as the fishbone diagram because it looks like a child’s drawing of a fish skeleton. We can also call it as a cause-and-effect diagram because we often use it to show the cause of some effect.

Japanese quality guru Dr. Kaoru Ishikawa develop it to express one of the basic principles of TQM, that the desired product, target, or other outcome is attained not by directly controlling the results themselves but by controlling the processes that produce those results during lean transformation.

Fishbone Diagram organizes the ideas and recognizes the relationship between potential causes & an effect or a problem by formatting, arranging & organizing potential causes into themes and sub-themes in preparation for a cause identification effort.

Draw the “fish skeleton” of an Ishikawa diagram in such a way that the “head” of the fish points to the right. The head represents the problem or cause. The “bones” of the fish branch off the central, horizontal spine and angle back to the left. Every bone presents one big cause of the event. You can add smaller bones branching off each major bone to represent sub-causes related to that major cause.

Basic cause categories could comprise:

• People– personnel engaged with the process; stakeholders etc.

• Methods – process for doing the task and the particular requirements for doing it, such as policies, procedures, laws, rules & regulations.

• Machines – Any equipment, computers, tools, etc. needed to achieve the job.

• Materials – Raw materials, parts, paper, etc.

• Measurements – Data produced from the process that is uses to evaluate its quality.

• Environment – The conditions, such as location, time, temperature, and culture in which the process operates.

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2. Flow Chart

Flow Chart is one of another 7 QC tools which is a way to organize data, and in particular of separate data into meaningful groups. Itis also known as Stratification. A flow chart is a visual representation of a process that demonstrates:

• Who finishes What activities and in what order.

• Handovers between departments or individuals.

• Internal & external operational boundaries.

Typical stratification groups used for quality control purposes include:

• Who – the people engaged with the problem. For instance, which operator or crew was working at the time?

• What – products, raw materials, machines.

• Where – physical location, or a location on a machine.

• When – time of day, shift, or process step when the problem occurs.

3. Check Sheet

The check sheet is another one of the 7 QC tools that are a structured, prepared form for gathering and analyzing data. A checklist aims to summarize, and in some cases; graphically represent a tally count of event occurrences. 

The defining feature of a check sheet is that data is recorded by making marks (“checks”) on it which makes data collection more effective and transparent. Further, A check sheet contains several regions and marks made in several regions have distinct significance. So, Data is read after observing the location and number of marks on the sheet. Check sheets answers the Five Ws. 

• Who recorded the check sheet?

• What was collected?

• Where the data was collected (facility, room, apparatus).

• When the Data was collected (shift, day of the week).

• Why the data was collected?

4. Pareto Chart (80/20 Rule)

Pareto charts are based on the Pareto principle, or 80/20 rule, which states that roughly 80% of the effects are caused by 20% of the problems. The graph – named after economist & political scientist Vilfredo Pareto – is a type of chart that contains both bars and a line graph. 

A Pareto chart is a bar graph in which the cumulative total is shown by the line and individual values are shown in descending order by bars. So, The vertical axis on the left often represents the frequency of occurrence. Further, The right vertical axis represents the cumulative percentage of the total number of occurrences.  

Arranging the bars in this manner permits you to visually identify the most significant data groups, which helps you prioritize the most significant problems. In quality control, We use the Pareto chart to represent types of customer complaints, sources of defects, and similar issues.

We use Pareto Chart when-

• When analyzing data about the frequency of problems or causes in a lean manufacturing process.

• When there are so many problems, you want to focus on the most significant.

A Pareto chart focuses attention on priorities when making decisions. It is a good communication tool that describes the data in a simple and easy-to-read bar diagram.

5. Histogram

 The histogram represents the frequency of values in the form of a bar graph. A histogram shows statistical information in the form of rectangles to present the frequency of data items in successive numerical intervals of identical size. In the histogram mostly, We show the independent variable on the horizontal axis and the dependent variable is shown on the vertical axis.

To create a histogram, start by determining the intervals or “bins” that represent the range of values, then determine how many values fall into each bin.

We use histogram when:

• You want to analyze whether a business transformation process can meet the customer’s needs.

• Determining whether the outputs of two or more processes are different.

6. Control Chart

The control chart is a graph that represents how a process changes over time. They’re also famous as the Shewhart chart or process-behavior charts. The vertical dimension of the chart generally represents a process value or measurement, and the horizontal dimension generally represents time–when the measurement was taken or how often it was taken.

A control chart always has a central line that represents the average or means, an upper line for the upper control limit, and a lower line for the lower control limit. Compare the current data to these lines, to conclude whether the process variation is unpredictable or consistent (in control). Control charts are great for analyzing & reducing variation in a process.

Few examples of how we can use process control at production facilities:

• A pizza company might track how much pepperoni is on their pizzas.

• A power company may track the amount of energy produced.

We use Control Chart when-

• When predicting the expected range of outcomes from a process.

• When determining whether a process is stable.

7. Scatter Diagram

Scatter diagrams also famous as scatter graphs, scatter charts, scatter plots, and even scattergrams. We use these to help understand how variables are related and also to identify the root cause. It presents the relationship between the two variables and supports the interpretation of the correlation coefficient. The data is shows collection of points.

We present the Independent variable on the horizontal axis. We measured the dependent variable on the vertical axis. You can then draw a trend line to study the relationship between the variables. The closer the data points align with the trend line or curve, the stronger the relationship, and the more probably it is that a change in one variable will change the value of another variable.

FAQs

Key Takeaways

• Root Cause Analysis helps identify the underlying reasons behind defects or issues.”
• Pareto Chart prioritizes problems by focusing on the most significant factors.”
• Control Charts monitor process stability and performance over time, aiding in continuous improvement.