The 7 Quality Control (QC) Tools Explained with an Example!

Summary

In this video, Andy from CQE Academy discusses the Seven QC Tools essential for quality management and problem-solving. He covers each tool, including flow charts, check sheets, Pareto charts, cause-and-effect diagrams, scatter diagrams, histograms, and control charts. Using a practical example involving toaster defects, Andy demonstrates how to apply these tools to identify and address quality issues, ultimately reducing defects by controlling variables like humidity. The video is valuable for those preparing for Green Belt, Black Belt, or CQE exams, as well as professionals seeking to enhance their quality improvement skills.

Takeaways

• 🛠️ The video covers the seven QC tools essential for quality improvement and problem-solving.
• 📝 The tools discussed include flow charts, check sheets, Pareto charts, cause and effect diagrams, scatter diagrams, histograms, and control charts.
• 📈 Flow charts visually depict the sequence of a process, promoting a common understanding and simplifying complex processes.
• 📊 Check sheets are vital for collecting, organizing, and analyzing data, ensuring decisions are based on accurate information.
• 📉 Pareto charts help identify the most significant issues by applying the 80/20 rule, focusing on the vital few causes of problems.
• 🐟 Cause and effect diagrams, also known as fishbone diagrams, are used to identify potential root causes of problems through structured brainstorming.
• 🔍 Scatter diagrams illustrate relationships between two variables, helping to determine potential correlations without assuming causation.
• 📅 Histograms display the frequency of data over time, helping to understand process variation and distribution patterns.
• 🔬 Control charts monitor and confirm that processes remain in control by showing data within control limits and detecting any significant changes.
• 📉 Practical example: The video uses a toaster defect problem to demonstrate the application of these tools, highlighting how controlling humidity can reduce defects.

Q & A

What are the seven QC tools discussed in the video?

The seven QC tools are the flow chart, check sheet, Pareto chart, cause and effect diagram, scatter diagram, histogram, and control charts.

Why are these seven QC tools important according to the video?

These tools are considered incredibly powerful for solving problems and making improvements, with the claim that 95% of quality problems can be solved with these fundamental tools.

What is the purpose of a flow chart in the QC tools?

A flow chart is a visual tool that helps depict the flow or sequence of a process, making complex processes simple and promoting a common understanding of the process.

What is a check sheet and how is it used?

A check sheet is a simple tool for collecting, organizing, and analyzing data. It ensures that decisions are based on data and should include metadata such as who, when, and where the data was collected.

What is the Pareto principle and how does it relate to the Pareto chart?

The Pareto principle, or the 80/20 rule, states that 80% of problems are often due to 20% of causes. A Pareto chart helps identify these 'vital few' causes so that efforts can be focused on the most significant issues.

What is a cause and effect diagram and what is its purpose?

A cause and effect diagram, also known as a fishbone diagram or Ishikawa diagram, is used to systematically identify potential causes of a problem and understand the relationship between them.

How can a scatter diagram be used in QC processes?

A scatter diagram plots pairs of data to identify and analyze the relationship between two variables, helping to understand if and how one variable affects another.

What does a histogram show and why is it useful?

A histogram is a bar chart that graphs the frequency of occurrence of continuous data, showing the distribution and variation within a process, which helps in understanding process behavior and capability.

How does a control chart help in maintaining process control?

A control chart monitors the stability of a process over time, ensuring that it remains within control limits and only experiences normal variation, confirming the effectiveness of implemented changes.

What was the specific example used in the video to demonstrate the use of the seven QC tools?

The example used was reducing the number of defects in a toaster manufacturing process, where the tools were applied to identify and control for high humidity during assembly as a root cause of defects.

Outlines

00:00

📈 Introduction to the Seven QC Tools

Andy from CQE Academy introduces the seven quality control (QC) tools, emphasizing their importance in work efficiency, problem-solving, and preparation for exams like the Green Belt, Black Belt, and CQE. The video will cover an overview of the tools, their role in the problem-solving process, and a practical application to reduce defects in toasters. The quote from Kaoru Ishikawa highlights the power of these tools in solving up to 95% of quality problems. The session will also explain the Plan-Do-Check-Act (PDCA) cycle and the Define, Analyze, Improve, Control (DMAIC) methodology.

05:01

🛠️ Utilizing the Flow Chart and Check Sheet

The first tool discussed is the flow chart, a visual representation of process steps that simplifies complexity and fosters a common understanding. The speaker uses a toaster example to demonstrate creating a flow chart, emphasizing the importance of boundaries and team collaboration. The second tool, the check sheet, is introduced for data collection with a focus on including metadata for data integrity. The team uses the check sheet to identify the most frequent defects during final testing, setting a goal to reduce defects by 25% based on collected data.

10:02

📊 Analyzing Defects with the Pareto Chart

The Pareto chart is introduced as a tool to apply the 80/20 rule, identifying the most significant issues affecting quality. The video explains the historical background of the Pareto principle and its application in focusing on key defects. Using the check sheet data, the Pareto chart reveals that 'control PCB issues' account for 40% of defects, indicating the primary area to target for improvement. The speaker also discusses the importance of teamwork and structured analysis in identifying root causes.

15:02

📚 Cause and Effect Diagram and Scatter Diagram

The cause and effect diagram, also known as the fishbone diagram or Ishikawa diagram, is detailed as a method for root cause analysis. The process involves a well-defined problem statement and structured thinking across different categories like the 8Ms (Man, Machine, Material, etc.). The video also introduces the scatter diagram for understanding the relationship between two variables, using the example of how humidity affects defect rates. The speaker cautions against assuming causality from correlation alone.

📈 Histogram and Control Chart for Process Analysis

The histogram is explained as a tool for analyzing the pattern of process variation, allowing engineers to understand the behavior of a process and its capability when compared to specification limits. The control chart is introduced as a method to confirm process stability, ensuring that only normal variation is occurring. The video concludes with an example of how controlling humidity reduced defects in the toaster process, demonstrating the effectiveness of the QC tools in achieving the improvement target.

🎓 Conclusion and Resources for Quality Engineering

The video concludes with a summary of the QC tools' effectiveness in reducing defects by controlling humidity in the toaster example. The speaker invites viewers to engage with the content, offering a free course for those interested in becoming a Certified Quality Engineer (CQE). The course is available at CQE Academy's website and includes practice exams to assist in exam preparation.

Keywords

💡Seven QC Tools

The Seven QC (Quality Control) Tools are fundamental instruments used in quality management to analyze and improve processes. They include the flow chart, check sheet, Pareto chart, cause and effect diagram, scatter diagram, histogram, and control charts. These tools are emphasized in the video as essential for solving quality problems and improving processes in various contexts, including preparation for certification exams like the Green Belt, Black Belt, and CQE.

💡Flow Chart

A flow chart is a visual tool used to depict the sequence of steps in a process. It helps simplify complex processes and promotes a common understanding among team members. In the video, the flow chart is presented as the first QC tool, used to outline the process of reducing defects in a toaster production scenario, highlighting its importance in the planning phase of problem-solving.

💡Check Sheet

A check sheet is a structured form for collecting and analyzing data. It ensures that data is gathered systematically, facilitating accurate decision-making. The video demonstrates the use of a check sheet in the toaster example to collect defect data, emphasizing the need for metadata (like who, when, and where) to maintain data integrity and quality.

💡Pareto Chart

A Pareto chart is a bar graph that prioritizes issues based on their frequency or impact, helping to identify the 'vital few' causes that contribute most to a problem. The video uses a Pareto chart to analyze defects in toaster production, illustrating the 80/20 rule where 80% of problems are often due to 20% of the causes, thus guiding where to focus improvement efforts.

💡Cause and Effect Diagram

Also known as a fishbone diagram or Ishikawa diagram, this tool helps identify, explore, and display the possible causes of a specific problem. It categorizes potential causes to facilitate thorough analysis. In the video, it's used to examine the root causes of PCB failures in the toaster example, employing the 8Ms (categories like materials, methods, and machines) for a structured approach.

💡Scatter Diagram

A scatter diagram plots pairs of numerical data to investigate potential relationships between two variables. It helps in understanding correlations. The video uses a scatter diagram to analyze the relationship between humidity and defects in toaster production, warning viewers not to confuse correlation with causation.

💡Histogram

A histogram is a type of bar chart that represents the frequency distribution of continuous data. It helps visualize the pattern of variation in a process. The video demonstrates how a histogram can be used to analyze relative humidity data over time in the toaster example, providing insights into process behavior and variation.

💡Control Chart

A control chart monitors process performance over time, distinguishing between common cause variation (normal) and special cause variation (abnormal). It is essential for ensuring a process remains in control after changes are made. In the video, control charts are used to track defect rates in toaster production before and after controlling humidity, showing their role in maintaining improvements.

💡Plan-Do-Check-Act (PDCA) Cycle

The PDCA cycle is a continuous loop of planning, doing, checking (studying), and acting, used to achieve continuous improvement in processes. The video mentions PDCA as a framework for applying the QC tools to solve the toaster defect problem, illustrating its iterative nature in process improvement.

💡Defects

Defects refer to imperfections or faults in a product or process that reduce its quality. The video uses the example of defects in toaster production to explain how the Seven QC Tools can be applied to identify, analyze, and reduce these defects, thereby improving product quality and process efficiency.

Highlights

Introduction to the seven QC tools: Flow Chart, Check Sheet, Pareto Chart, Cause and Effect Diagram, Scatter Diagram, Histogram, and Control Charts.

Flow Chart: A visual tool that simplifies complex processes and promotes a common understanding.

Quote from Dr. Deming: 'If you can't describe what you're doing as a process, you don't know what you're doing.'

Check Sheet: A powerful tool for collecting, organizing, and analyzing data with an emphasis on including metadata for data integrity.

Pareto Chart: Helps identify the vital few issues that account for most problems, using the 80/20 rule popularized by Joseph Juran.

Cause and Effect Diagram (Fishbone/Ishikawa Diagram): Used to identify potential root causes and contributing factors of a problem.

Scatter Diagram: Illustrates the relationship between two variables, highlighting the importance of distinguishing correlation from causation.

Pearson Correlation Coefficient: Quantifies the relationship between variables, ranging from -1 (perfect negative correlation) to 1 (perfect positive correlation).

Histogram: A bar chart that displays the frequency of occurrence of continuous data, useful for understanding process variation and capability.

Control Chart: Monitors and controls processes to ensure changes are effective over time, distinguishing normal variation from special cause variation.

Application of the seven QC tools in a practical example to reduce defects in a toaster manufacturing process by 25%.

Ishikawa's quote on QC tools: 'As much as 95% of quality problems can be solved with seven fundamental tools.'

Importance of team-based activities in quality improvement processes.

Use of Plan-Do-Check-Act (PDCA) or DMAIC cycle in problem-solving with QC tools.

Encouragement to use brainstorming and cross-functional teamwork to identify potential root causes in the cause and effect diagram.

Transcripts

hey guys andy here with cqe academy and

in today's video i want to talk about a

really important topic

which is the seven qc tools now whether

you just want to get better at work and

use these tools in your everyday job

or you're preparing for something like

the green belt exam or the black belt

exam or the cqe exam

today's lecture is for you all right

let's head over to the computer get

started

all right let's go ahead and jump in

right into the agenda so we're gonna

start with a brief

intro of the seven qc tools kind of talk

about all of them and how they fit into

the

problem solving process or the the

improvement process and then we're gonna

go through each one we're gonna start

the flow chart

the check sheet the pareto chart the

cause and effect diagram

scatter diagram histogram and then the

control charts and then

along the way as we go through this

we're actually gonna work a problem

using all seven tools and we're gonna

reduce the number of defects

associated with our toaster all right

let's go and get started so the seven qc

tools

i love this quote from kerou ishikawa

who said

as much as 95 of quality problems can be

solved with seven fundamental tools and

i

absolutely agree with that i think these

tools are probably

the seven most powerful tools whether

you're talking about

green belt or black belt or quality

engineering it doesn't matter

these seven tools are incredibly

powerful for

solving problems and making improvements

and and this is a really important topic

by the way as we go through this i'll

make sure to talk about

where we're at in something like the

plan do check act or the domain cycle

we're gonna solve a problem with our

toaster and we'll we'll use either the

domain or the plan do check out process

to do it

all right let's get into it all right so

the very first tool is the flow chart

and what a flowchart does is say it's a

visual tool

that helps you depict the flow or the

sequence of a process

this could be things like the flow of

information or the flow of tasks or

material or people or decisions

it doesn't matter the reason that a

flowchart is so incredibly valuable is

it makes a

really complex process simple and

it promotes a common understanding of a

process anytime you get more than one

person in a room to talk about a process

there's likely going to be disagreement

about how the process works

and i love using this analogy often

times when when we sit down to

analyze a process there's what

management thinks is happening

there's what the procedure says is

happening there's what's actually

happening on the production floor

and then there's what could be happening

and the beauty of a flow chart is it it

does just that it gets everyone on the

same page

about what's actually happening and i

love this quote

from dr deming who said if you can't

describe what you're doing as a process

you don't know what you're doing and the

best way

to describe what you're doing is to use

a flowchart

and that's why this tool is so powerful

if you're in the planning phase of the

define phase

it's really good to use a flow chart

define your process

and then use that flow chart to plan out

your experiment and plan out how you're

going to make an improvement

so let's do just that let's say we're

talking about our toaster

and we want to make an improvement right

and so the first thing we're going to do

is we're going to start with the

boundaries we want to analyze a process

but we want to start with our boundaries

first

so we're going to go from receiving a

work order to completing a workload

that's the boundaries of our flow chart

now i've got the team here because all

of these activities all these tools are

all team based so imagine you're sitting

down with your team

and the first thing you're going to do

is brainstorm all of the steps in the

process right

talk to the experts how does the process

work use post-it notes right don't try

to do this in some software

use post-it notes write down all the

activities and then once you're done

brainstorming

organize those thoughts into that

logical flow

that logical sequence of activities for

your process

and now that we have our process here

we're in that planning phase and we want

to create a target right

what sort of improvement are we going to

make and we want to reduce defects by 25

now we can't make an improvement and we

can't solve a problem without data

and we know that most of our defects

happen during final testing

so now we need to collect a little bit

of data and this is where the check

sheet comes into play

so the check sheet is a very simple tool

for collecting

organizing and analyzing data every

problem you solve or every improvement

you make

should be based on data and the check

sheet is probably the most powerful tool

for collecting data

now there's something wrong with the

check sheet that i'm showing you here on

the screen

and that problem is is it doesn't have

any metadata

if you're collecting data and you want

to make a high quality decision

using that data you also need metadata

so when you're creating your check sheet

don't forget to include things like who

and when and where

all those key elements of data integrity

and data accuracy

are really important for making high

quality decisions

okay so we've got the team together and

again we did a little bit more

brainstorming we said

okay at final testing we have eight

defects that we want to collect some

data on so we create this check sheet

we've got our metadata here

we hand this off to the team and they

come back to us a week later

with a bunch of data now this is

fantastic we finally have some data

that we can analyze and the question is

which defect

do we focus on i want to improve our

target so we originally said

we want to reduce defects by 25 percent

well now that we have a little bit of

data we can actually create a target

so we have 145 defects across a whole

week that's seven days

that means we're averaging about 20 to

21 defects

per day now if we can reduce that by 25

percent

we will eliminate five defects per day

now we obviously can't focus on all

these defects so the real question is

how do we know

what to focus on and that's where the

pareto chart comes into play

so the pareto chart is another qc tool

that allows you to

analyze your data in search of the

pareto principle

so what it what is the pareto rule what

is this 80 20 rule

so this this is a a natural phenomenon

that was discovered by a guy named

vilfredo paredo

he's an italian researcher who was

studying

land ownership and wealth distribution

in italy

and in europe and what he found is that

80 percent of the land

was owned by 20 percent of the people

and this 80 20 rule in this 80 20

phenomenon

was also experienced by a guy named

joseph duran

now he gave credit for the tool to

wilfredo praeto but he was the one who

popularized this idea

of the 80 20 rule and this idea of the

pareto chart and what he told us and

what he taught us is that

a pareto chart helps you separate the

vital few

from the trivial many now what did joran

mean what he means is when you're

solving a problem there's often

one or two key issues key root causes or

key

defects that you need to focus on to

have a major impact

on that particular situation and that's

exactly what you see here

when we take our data from the check

sheet and we put it into this pareto

chart

we see that control pcb issues accounts

for

nearly 40 of our defects you can see if

we come across here

we've got 40 percent of our defects

coming directly from control pcb

now there's two things happening on this

graph obviously there's the blue bars

which are simply just the frequency or

the count

of defects that occurred throughout the

week and then this black bar is actually

the cumulative

line so this first defect accounts for

40 percent and then we go up and up and

up all the way to 100

now that we have this pareto analysis we

know that control pcb

is our primary issue it tells us what to

focus on now we still don't understand

why

these issues are happening and this is

where something like the cause and

effect diagram can be incredibly useful

so this is the the fish bone diagram or

the ishikawa diagram

there's all sorts of different names for

it but it is a cause and effect diagram

and the way this works is we start with

the effect

that's over here on the right that's the

head of the fish here in orange this is

our effect

and so step one of the cause-and-effect

diagram is to start with a really

well-written problem statement

so i've put in pcb failures but in

reality you want to have a

much more descriptive problem statement

than this and once you have this effect

you can start working through the the

fish bone process

to analyze all of the potential causes

and failures

now i'm showing here what's called the

8ms and this is the beauty of the

fishbone process

is that it's a well-structured approach

to root cause analysis

it forces you to think about all of the

potential

different categories or scenarios or

causes that might be contributing to

your problem

now along with the cause and effect

diagram are a number of tools that you

should be using

so i would recommend you get out your

flow chart look at your process

use your flow chart and and ask yourself

how might each step in the process fail

and contribute to the the effect that

we're seeing teamwork is also a must

here

you're not going to be a subject matter

expert in all of those eight m's and you

need people from operations and

engineering and quality and r d

and marketing and maintenance to really

do a thorough analysis

in each of those areas to truly

understand the root cause and then of

course brainstorming

you know you're going to have to

creatively think about and talk about

and discuss

potential root causes that maybe you're

not even aware of

and then the five-way analysis i love

the five wise it really helps you go

from a high-level symptom

down to the true root cause and really

ask why why why

to truly get to those those real root

causes that you need to address

and then as you have that team

discussion and you you go through the

process

you can identify potential root causes

and contributing factors

to the problem you're trying to solve

now obviously again it's we have to go

back to that parade of principle we

can't focus on everything

we have to talk about the most likely

root causes and the most likely

contributing factors

so again at the end of your cause and

effect diagram you might identify three

or four issues that you need to study

further

now i wanna i wanna talk about this one

high humidity during assembly

now as we were working through the cause

and effect diagram process the engineer

who was helping us

looked at our check sheet and noticed an

interesting pattern

what they noticed here and i've

highlighted here in yellow is that

sunday monday tuesday we

we only had a few defects right six and

four and one whereas on wednesday

thursday friday you'll notice that our

defect rate jumped up a little bit

and what the engineer remembered is that

we had a rainstorm come through

on tuesday night and the humidity level

in the facility really jumped up

and so what the hypothesis here is that

humidity

is affecting our defect rate so i've

created this little table here to show

the days of the week

along with the defects and the humidity

now to truly understand this

relationship

we have to create a scatter diagram

so here's exactly what that scatter

diagram looks like

what we do here is we're plotting pairs

of data so for example on sunday we had

six defects

and 18 humidity you can see that right

here that's this data point right here

we had six defects

18 humidity now the way this scatter

diagram works

or you might hear this called an xy

scatter plot is here on the x-axis

we put our controllable variable our

independent variable

and then on the y-axis we put our

response variable so here we believe

that

relative humidity is the the independent

variable that is affecting

our response variable which is defects

and you can see here that there appears

to be some relationship

between pcb failures and humidity

now it's really important when you're

looking at the scatter diagram not to

assume that this relationship

is a causal relationship right there's

this really important concept that you

can have

correlation without causation two

parameters or two variables can

correlate

without having a cause and effect

relationship so let's assume though

let's assume that we've done a doe here

and we've proven

that humidity has an effect on our pcb

defects

we could come back to the scatter

diagram we could say okay

our target for pcb defects is five or

less let's call it let's call it five or

less

and so we come down here to humidity and

say okay we wanna control

humidity to around 20

to keep our defects low does that make

sense and that's a this is a great way a

scatter diagram is a great way to

understand the relationship

between two possible variables now once

you've done your scattered diagram

you can quantify the relationship

between those two variables

so what i'm showing here is the pearson

correlation coefficient

and this coefficient ranges from

positive 1 all the way

over here on the left to negative 1 all

the way over here on the right

and that ranges from a perfectly

positive correlation here you can see

that as x changes y changes

identically and then same thing here

with r equals minus one this is a

perfect negative correlation

now as we get closer to zero we start to

lose that relationship

so an r value of zero means there's no

correlation between those two parameters

as x changes

y basically does whatever it wants

there's no relationship between those

two variables

now the next thing we could do in our

analysis is to look at

relative humidity over time so let's say

we go out

we talk to our facilities engineers we

say okay give us the relative humidity

within our environment

you know every six hours for the last

six months and we can take that data and

we want to plot it because we need to

understand

how relative humidity is changing within

our facility

and one of the ways you could analyze

that data is with a histogram

so a histogram is just a very simple bar

chart that graphs the frequency of

occurrence

of continuous data and again this is a

great way to talk about your process

every process or every product or every

quality attribute out there

has some level of random normal

variation

that will often occur in a pattern and

as engineers we need to understand what

is the pattern

associated with with our outputs or our

process and a histogram is a great way

to understand the pattern or the

variation in your process

now you might grab this data and you

might get like a skewed distribution or

maybe a bimodal distribution

or exponential distribution there's all

sorts of distributions you might get

but it's great to know how your process

is behaving

now the other beautiful part about a

histogram is you can take this data

and let's overlay some some

specification limits right

now what we have is the beginnings of

process capability

so the histogram is a fantastic tool to

quantify and understand how your process

behaves

and if you compare that against the

specification limits we can now start

talking about process capability

okay so we're on to the very last and

final qc tool

let's assume we now control for humidity

and we want to make sure that that

change has been effective over time

a control chart is the right tool or the

perfect tool to do that

so what is a control chart it is

essentially a tool that allows you to

confirm that your process

is in control now when i say in control

what i mean is

that you're only experiencing normal

variation when your process is

experiencing normal cause variation

your data should fall with within those

control limits

by the way if you're new to spc i have a

whole separate video on control charts

you can go check it out

i've got both the x bar on our chart as

well as attribute data

and a control chart is a fantastic tool

to use at the end of a project

to monitor and control your process and

make sure that your changes were

effective

and let's take a look at what this looks

like for our particular process

so here's our process right the first

week of data you can see we're really

all over the place

and our control limits are really wide

because we're not controlling for

humidity

and we've got all this data and you can

see on average we have about

eight defects per day right we're really

jumping around here and then let's say

on day nine we start controlling for

relative humidity

and we've got our our control chart

we're collecting data and you can see

that for the next

you know 20 plus days our defect rate

has dramatically fallen in fact our new

mean defects per day is around three

so essentially we've gone from eight

defects per day down to three defects

per day

and we've hit our target of reducing

defects by 25 percent

we've gone from 20 plus defects a day

down to about 15

all by controlling relative humidity in

our process all right that's it for

today

i hope you enjoyed it if you did hit

that like button also if you're serious

about becoming a cqe

i've got a free course go check it out

it's at cqe academy.com

free course where i cover the top 10

topics on the cq exam

and i also give you a bunch of great

free practice exams to help you on that

journey

all right i hope you enjoyed it thanks

so much i'll see you again bye