7 quality control tools (sqc model) [march 2009]

Tuesday, April 11, 2023 1

SEVEN QUALITY

IMPORVEMENT

TOOLS

FAHAD MAHMUD MIRZA

7QCENGINEERING MANAGEMENT

QUALITY IMPROVEMENT IN TECHNICAL CONCERNS

Tuesday, April 11, 2023Fahad Mahmud Mirza 2

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Quality Improvement falls in the major subject of Quality Control and Management…

Quality Improvement:

“Systematic approach to reduction or elimination of waste, work-back flow, rework, and losses in production process”

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Quality has to be caused, not controlled… -Phil Crosby 7QC


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Quality & Productivity Improvement

While companies have adopted different methods to control design and manufacturing outcomes, the intent is always the same: quality improvement.

Quality improvement efforts work best when problems are addressed systematically using a consistent and analytic approach; the methodology shouldn't change just because the problem changes. Keeping the steps to problem-solving simple allows workers to learn the process and how to use the tools effectively.

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Quality is never an accident, It is always the result of intelligent effort...

-John Ruskin 7QC


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Quality Improvement Requirements

• Organizational commitment

• Communicating the commitment

• Organizational culture

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Quality means doing it Right when no one is looking...

-Henry Ford 7QC


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Quality Management

Application of a system to manage a process consisting of structure, responsibilities, and procedures that achieves the quality desired

Quality Plan

A document that describes the standards, practices, resources and processes specific to producing quality

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Quality is not an act, It is a habit…

-Aristotle 7QC


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Quality Assurance

All the planned and systematic activities implemented within the quality system that can be demonstrated to provide confidence that a product or service willfulfill requirements for quality

Quality Tool

An instrument or technique to support or improve the activities of process management and improvement to meet the characteristics of quality

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Professionalism means consistency of Quality…

-Frank Tyger7QC


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Quality Improvement Methods-

ISO 9004:2000 Guidelines for performance improvementISO 15504-4: 2005 Process assessmentQFD — Quality Function DeploymentKaizen — change for the better; the continual improvementSix Sigma — 6σ, methods such as Statistical Process ControlPDCA — Plan-Do-Check-Act cycle for quality control purposesTaguchi Methods — Quality loss function and Target specificationsTQM — Total Quality ManagementTRIZ — Theory of Inventive Problem SolvingBPR — Business Process Re-EngineeringQuality Circle — People oriented group approach to improvement

7QC — Also known as SQC (Seven Quality Control Tools)

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Easy to implement and follow up, the most commonly used and well-known quality process is the Plan-Do-Check-Act (PDCA) cycle

P Plan: Define a problem or opportunityAnalyze the situation and Develop a implementation Plan

D Do:Implement corrective actionsDocument procedures and observationsUsing data-gathering tools to collect information

C Check:Analyze informationMonitor trendsCompare obtained results with expected results

A Act:Expected results: Do Nothing!Not-Expected results: Repeat PDCA cycleDocument the process and revised plan


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Process and the Sub-Process

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Quality is free, but only to those who are willing to pay heavily for it…

-Philip Crosby


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One of many methods to ease the quality improvement process was introduced by Kaoru Ishikawa

It was called Seven Tools of Quality.

Ishikawa believed that 95% of a company’s problems can be solved using these seven tools

The tools are designed for simplicity so average person can have less complicated statistical analysis

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Seven Tools of Quality Improvement

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FLOW CHARTCAUSE & EFFECT DIAGRAMSCHECK SHEETS

HISTOGRAMS

PARETO DIAGRAMS

CONTROL CHARTS

SCATTER DIAGRAMS


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Flow Chart

1. Flow charts describe sequence of activities graphically in accomplishing a task.

2. It must reflect the actual process rather than what the process owner wants it to be.

3. By generating flow charts, process owner can understand the process and working relationship between people and organization will be clarified.

4. Furthermore, flow charts will show the duplicated effort and other non value added steps.

5. So process owner can identify the target specific steps in order to make continuous improvement.

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Flow Chart

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DOCK

RECIEVE

INSPECTION

FINAL TEST

SHIPPING

DOCK

PAINT AND AESTHETICS

SUB-OPERATIONS

ASSEMBLY

INSPECTION AND TESTING


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Cause & Effect Diagrams

1. Cause and effect diagrams are also called Ishikawa diagrams or fishbone diagrams.

2. These diagrams show a relationship between the effect of the problem and the causes.

3. Although cause and effect diagrams can be developed by individual, but it is better to be brainstormed by a team.

4. To help in identifying the causes, people used to take 5 potential factors which are man, machine, material, method, and environment as the guidance.

5. Cause and effect diagrams consist of 2 sides. The right side lists the effect or the problem, while the left side lists the causes of the problem. 7QC


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Cause & Effect Diagram

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MATERIALS METHODS PEOPLE

MEASUREMENTS MACHINES DESIGNS

RESULT


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Check Sheets

1. Check sheets are the paper forms for collecting data in real time easily and concisely.

2. According to the data on check sheets, frequency or pattern of the events, problems, defects, etc. can be observed.

3. These data are then used as input data for other seven quality tools such as histograms and Pareto diagrams.

4. Furthermore, collected data on check sheets can be used as input to understand the real situation, analyze occurring problem, control the process, make the decision, and develop planning.

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Check Sheets

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Defective Item

Mon9/3

Tue10/3

Wed11/3

Thu12/3

Fri13/3 Total

Mold Cracked 5 3 6 3 4 21

Fibers 2 0 5 1 0 8

Grit 4 2 3 5 0 14

Pinholes 1 5 0 2 1 9

Cracks 0 1 1 0 0 2

Other 1 3 0 0 3 7

Total 13 14 15 11 8 61


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Histogram Charts

1. Histograms are bar graphs that present the frequency distribution of data.

2. The horizontal axis represents the class interval of data while the vertical axis represents the frequency of each class interval.

3. Not only for displaying data, histogram can also be used as a tool for summarizing and analyzing data.

4. The particular values of histogram are:

• Summary graph of frequency distribution• Shows data in various ranges• Conveys symmetry

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Histogram Charts

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0-9 20-29 40-49 60-69 80-89

Production 2.4 4.4 1.8 2.8 3.6

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2.25

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3.75

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Example


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Scatter Diagrams

1. Scatter diagrams describe the correlation between 2 variables, so it can be identified whether those 2 variables are related.

2. After developing cause and affect diagrams, sometimes people use scatter diagrams to determine objectively whether the cause and the effect are related.

3. By looking at a glance to the scatter diagrams, process owner can analyze the positive/negative correlation of 2 variables. When the trend line goes from the bottom left to the up right, it means those 2 variables have positive correlation. Otherwise, if the trend line goes from the up left to the bottom right, and then it means those 2 variables have negative correlation. 7QC


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Scatter Diagrams

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0 2 4 6 8 10 12 14 160

1

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Relationship between Variables

Part Clearance

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Control Charts

1. Control charts were invented by Walter A. Shewhart in 1920s.

2. The maximum limit often called upper control limit and the minimum limit often called lower control limit, while the central line represents an estimate of the process mean.

3. If the value is within control area, the process can be stated as a controllable process.

4. The value outside control area indicates that the process is no longer stable because of some variation causes. Thus, this process needs proper corrective actions to eliminate the sources of variation.

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Control Charts

7QC5 10 1573.97573.98

73.98573.99

73.99574

74.00574.01

74.01574.02

74.025

MedianValues

Samples

Observations Average

1…15

74.030 … … … 74.008

73.988 … … … 74.002

74.010…

74.008Median : 74.001


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Pareto Charts

1. Pareto diagrams consist of bar graph and line graph that describe the proportion of each problem cause toward the overall cause.

2. According to these quality tools, the major factor of the problem can be identified. Thus, it helps process owner in prioritizing the problem to be solved first.

3. As Dr. J. M. Juran said, 80% of the problems are caused by 20% of the potential sources.

4. Not only to identify the major problem, pareto diagram can also be used to analyze the improvement after solving some problems.

5. Process owner can evaluate the process before and after solving the problems. 7QC


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Pareto Charts

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Benefits

1. Many people in the industries are undoubtedly familiar with many of these tools and know their application, advantages, and limitations.

2. However, this must ensured that these tools are in place and being used to their full advantage as part of their quality system procedures.

3. Flowcharts and check sheets are most valuable in identifying problems, whereas cause and effect diagrams, histograms, scatter diagrams, and control charts are used for problem analysis. Pareto diagrams are effective for both areas.

4. By properly using these tools, the problem-solving process can be more efficient and more effective.

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THANK YOU

ENGINEERING MANAGEMENTQUALITY IMPROVEMENT IN TECHNICAL CONCERNS

7QC

Persistence is the twin sister of excellence. One is a matter of quality; the other, a matter of time…

Even though if quality cannot be defined, you know what quality is