7 Quality Control Tools

In today scenario creation of value is the primary concern for any organisation. The value is created by providing good satisfaction to the customer. The product should be value for money. Total quality control is a tool that creates belief in the customer that product is defect free.Here we will discuss 7 quality control you can implement in your organisation.

The seven quality control or tools of quality is a designation given to a fixed set of graphical technique identified as most helpful in troubleshooting issue related to quality.

These are basic tools because they are suitable for people with little formal training in statistics and because they can be used to solved the vast majority of quality related issue.

7 Tools are;-

1. Pareto Diagram

2. Cause and Effect Diagram

3. Graph

4. Check Sheet

5. Scatter Diagram

6. Histogram

7. Control chart

We will discuss it one by one 

1. Pareto Diagram: - Suppose you are a pizza company facing some problems, for example,

    i) Late delivery of Product

    ii) Wrong Delivery

   iii) Pizza has been eaten

   iv) Others

This tool is based on the idea that majority of defects are caused by few defective items, which classifies the quality problem into the 'vital view' and ' trivial many'. (80-20 rule)

As we know that the rule(80-20)  state that 80% of effects comes from 20% causes. for e.g your 80% sales come from 20% clients.

Pareto diagram is a type of bar chart in which horizontal axis represent categories of interest, rather than continuous scale. The categories are often "defects".

A cumulative percentage line helps you judge the added contribution of each category.

Pareto charts can help to focus improvement effort on the area where the largest gain can be made.

Procedure

1. Decide on the problem to be addressed or item to study and collect data.
2. Decide also the period for which the data is collected.
3. Arrange the data in order of decreasing size.
4. Calculate cumulative number and percentage
5. Draw the horizontal and vertical graph on graph paper.
6. Draw the bar graph
7. Draw the vertical axis on the right edge and scale it.
8. Draw the cumulative curve

And complete the diagram.

Let's take a practical example.

Project Name:	Pareto Diagram on Pizza co.
Name of Data Recorder:	Mohit
Location:	Delhi
Data Collection Dates:	1 April 2017 to 7 April
Defect Types/ Event Occurrence	Dates							TOTAL
	Sunday	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday
Wrong Delivery	4	6	5	4	3	2	1	25
Late Delivery of Product	1	2	1	5	6	2	0	17
Pizza has been eaten	0	1	0	0	0	0	0	1
Others	0	1	1	0	1	1	1	5
Defect 5
Defect 6
Defect 7
Defect 8
Defect 9
Defect 10
TOTAL	5	10	7	9	10	5	2	48

The histogram of this situation is

and the Bart chart of this example

And the Pareto Diagram

This diagram is incomplete because cumulative percentage line is not shown. using percentage at the right the diagram( vertical axis) we can depict the cumulative percentage line. Using cumulative percentage line we can use to depict 80-20 rule. That means we need to remove defect 1 and defect 2 for satisfying the customer.

Now we will Discuss the second quality control tool

Cause and Defect Diagram

Also called fishbone diagram.

it's a visual tool to identify, explore and graphically display, in increasing detail, all of the suspected possible causes related to a problem or condition to discover its root causes. Note that it is not a quantitative tool.

We adopt this diagram due to following advantages
1) In this team get focused on the content of the problem
2) Creates a snapshot of the collective knowledge of team
3) Create consequences of the cause of problem
4) Builds supports for resulting solutions
5) Focuses on causes, not on symptoms
6) To discover the most probable causes for further analysis
7)To visualise possible relationship between cause for any problem current or future
8) To pinpoint conditions causing customer complaints, process error or non-conforming products
9)  To provide focuses for discussion


Firstly we need to know this tool is used to prevent quality defect.  Each cause or reason for imperfection is a source of variation. Causes are usually grouped into major categories to identify these sources of variation.

In product/manufacturing the 5M+E is used. 5M stands for Man, Machine, Method, Material and Measurement. Here E stands for the environment.
In Transactional/Services, the 4P+M&E is used. Here 4P stands for People, Procedures, Policies and place. M&E stands for Measurement and environment.

For example

In this example variation sources are Machinery, Methods, Materials and People.
We focus on this variation sources and find that these are the primary reason for the late pizza delivery on Saturday and Friday.
as given in this diagram the possible cause may be
In machinery - Oven is small(internal force), Unreliable cars (External Force)
In People - Driver get lost(Internal Force), People don't show up(External Force)
In Material- Run out of ingredients
In Methods - Poor handling of large orders(Internal force), Poor dispatching

Use of Ishikawa diagram
-Recognise important causes
- Understand all efforts and causes
- To compare operational procedures
- To find major solutions
- To figure out what to do
- To improve the process


To be continued......................