Paying Tribute to a Century of Modern Quality Practices

Have you ever wonder when does the  quality practices begin.   In ancient days,  where a craftsman would be able to manage  all aspects of  transforming raw material to finished goods which will eventually be sold and he will also be the inspector of his own product.   An example would be a carpenter would choose a tree which would yield good wood to chop and he will transform  the wood into furniture.  He had a control on each step including inspecting his own work in the process making the part.  In this scenario  time to reach consumer is not a primary concern to finish the product.

Frederick Taylor (1856- 1915)  enabled mass production with his  principles of Industrial engineering   to building  products with higher  efficiency  and more systematic approach where product time to reach consumer become a primary concern.  Therefore mass inspection conducted by  trained inspectors is formulated in tandem with mass production to enable operator to focus on just transforming  the parts from raw materials or semi finished parts.  This could be the beginning of modern quality practices per American Society of Quality (ASQ).   Since then,  there are many quality philosophies being conceived over the last centuries by great quality gurus from America and Japan.  After world war II,  leading quality engineering experts Juran and  Deming had went to Japan to introduce quality management tools to help Japan to build up their manufacturing industry.  This had created a ripple effect where Japanese quality philosophies had been discovered.  Together all great gurus had contributed to the founding of modern quality management concepts in manufacturing industry.   

Modern quality practices adopted a lot of tools such as FMEA, 8D, advance product  quality planning (APQP)  from military and automobile  industry  as both  was the most advance industry hiring the best expert before the digital age.  With the invention of computer in digital age and the growth of semiconductor had created a need for more systematic quality improvement methods.  Thus systematic problem solving approach such as 6 sigma was conceived by Motorola in late 1980s can be used in continuous quality improvement.

We shall trace back the development of the modern quality techniques and philosophies using the table below. 

Era	Quality culture contributors	Quality principles and techniques	Origin
1900	NA	Mass quality inspection by Frederick Taylor	NA
1930	Walter Shewart	Statistical Process control chart	Bell Telephone
1930s -1980s	William Deming	Sampling, PDCA, help Japan industry to grow through his quality philosophy,  14 key principles to transformation which is foundation of total quality management	America to Japan to global
1930s -1980s	Joseph Juran	Adopt Pareto principle in quality analysis, cost of poor quality,  Juran trilogy Quality control, improvement and planning, quality from top management, quality cannot be achieved thru inspection,   Juran Quality handbook	America , Japan to global
1960s -1990s	Philip Crosby	Quality management and maturity, Zero Defects,	America
1960s -1980s	Kaoru Ishikawa	Concepts of quality circle, Fish bone cause and effect diagram	Japan
1960s -1970s	Genichi Taguchi	The Taguchi loss function,  Taguichi method in Design of experiment	Japan
1960s	Aerospace/Military	FMEA	America
1980s	Automobile	Advance product quality planning (APQP)	America
1980s	Semiconductor, Motorola	Quality improvement Six sigma methodology	America
1980s	International Organization for Standardization	Standardized quality management systems to ensure product meet customer requirement	Europe

The biggest quality principles contributions which lead to today quality engineering strategy and techniques happen after  World War II with aggressive movement to build up nation economy at both sides of Pacific. 

With so many quality tools and principles being developed in last century,  it is sad that today  there are not many organizations are able to execute quality tools well.  Perhaps we should focus on how to apply all the quality tools properly to improve manufacturing process and shifting the quality management paradigm from inspecting quality in parts to build in quality to parts in a manufacturing process.

Various Special Cause Problem solving methods used in Manufacturing Industry

Most of the consumer market products such as high end  electronic products,  smartphones , tablets  and computers need to go through a series of complicated manufacturing process to become a final consumer product.  This finished product could go through various manufacturing processes at different global locations with thousands of process steps across a multiple supply chain.

Each process step is consists of inputs, process and output which is could be repeated thousands of times to make a product.

• Inputs -  elements which involve in product creation

Man – Operator who make the product

Machine -  equipment which is needed to make the product

Method -  work instruction on how to make the product

Material -  raw material or semi raw material needed to make the product

Measure -  Inspection and test  needed to check product quality

Environment -  Temperature, humidity, electrical static discharge  (ESD) which could impact product

The process itself  -  series of unit operations/work and decision taken to transform raw material to a product  

    Outputs - WIP to final product  which will eventually being sold

Given the complexity  of the processes and multiple tier of supply chains to bring the product to consumer market,  it is very rare to find all process are well executed with no issues from start 1^st tier supply chain to final product.  Along the way it is inevitable to have special cause problems (unpredictable)  in process inputs which could cause sudden spike increase in defective product,  therefore systematic problem solving approach had been created.  (Refer to my previous  articles to know more about special cause).  Systematic problem solving approach such as 8 discipline could trace its roots to the automobile industries before the era of digital world.  Later on with the boom in electronic manufacturing,  companies such as Dell and HP had adopted this systematic approach  to resolve problems which happened in manufacturing process.  Over the years organization such as Dell had modify the 8 discipline (8D)  into more simplify 5 C format.

All good problem solving approaches should have the following criteria in systematic order :-

1. Understand and problem description

2.  Short term to contain problem from impacting customer

3.  Find root cause of the problem

4.  Establish action plan (corrective and/or preventive action) to address the      root cause

5.  Validate the effectiveness of the action  plan

Three of the most common problem solving approaches  use in manufacturing industries are  8D, 5C and 7 steps.  The table below compare them against each other to check if there any differences or actually they are the same per table below.  I have also include templates of those problem solving approach in the resources where you can download and use. 

Items	8D	5 C	7 Steps
Background	Developed  by Ford motors	Developed by Dell Simple to use	Unknown
Popularity	Most common used in electronics and automobile industry.  Over the years several big organization modify the steps slight to suit its need	Dell and its supplier	General application beyond manufacturing
What are steps	Define team Describe the problem Develop Containment Action Determine root cause Develop corrective action Develop preventive action Verify action Congratulate team	Characterize Containment Cause analysis Corrective action Closure	Problem statement Goal Present status Analysis Root cause Corrective action Monitoring

From the table below, all three problem solving methods  have the 5 systematic order and actually there is no difference if 5C, 8D or 7 steps.

Events	8D  Steps	5 C  Steps	7 Steps
Identify team/ understand problem	Define team Describe the problem	Characterize	Problem statement Goal Present status
Short term plan to contain problem from impact customer	Develop Containment Action	Containment	Present status
Find root cause of the problem	Determine root cause	Cause analysis	Analysis
Develop action plan to address problem root cause,	Develop corrective action Develop preventive action	Corrective action/preventive action	Corrective action
Verify action plan effectiveness	Verify action Congratulate team	Closure	Monitoring

Refer to this video on problem solving for more details.  

How to manage common cause and special cause to produce consistent good quality product?

There are a lot manufacturers who do NOT know about using process control to minimize process input variations  and much less about common cause and special variations.  Quality issues could happen due to poorly controlled common cause process variation  or  there is a sudden change in 5Ms 1E which is not well managed which become special cause variation.  Sometimes quality issue already exist,  however it is not detected in the manufacturing process due poor inspection or test coverage  or incorrect data collection and analysis.

In order to successfully reduce common cause and eliminate special cause,  we must able to know if the quality issues are contributed by common and special cause type of variation.  The approaches to manage special cause and common cause are very different. 

From article posted on 11 Sep 2017,  we have learned on how to detect common and special variations thru preset rule for reject count or using more advance statistical analysis,  statistical process control (SPC) chart.

Once we have detected and identified the type of variation then we should learned how to manage those variations to ensure we reduce or if possible eliminate those variations  to produce consistently good quality product.

Common cause variations could derived from several root causes, in 5Ms and 1 Es process input and cannot be eliminated.  However it can be reduced through systematic approach of measuring correctly, collecting and analyzing data statistically  to understand which 5Ms or 1E contributed to the source of variations.  Then we can create action plan to address source of variations such as optimizing certain machine settings which have an impact on quality parameter.  This methodology is known as six sigma pioneered by Motorola engineers in 1980s.  Six sigma methodology consists of 5-6 phases, abbreviation as DMAIC or DMAICR in some organization. Below are a snapshot of the six sigma approach.

Phase 1 – Define – Detect, understand, scope problem such as high reject rate for certain reject symptom

Phase 2 -  Measure – Identify  what is the measurement metrics which represent quality feature to understand current status.  Conduct measurement system analysis (MSA) to check if measuring process is  reproducible and repeatable to ensure data collect from an inspection or test or measuring process can be trusted and does not have too much variations.  Then only collect and analyze  quality metrics data to understand current reject rate or process performance.

Phase 3 -  Analyze -  Root cause analysis  through using fish bone diagram, 5 whys or fault tree analysis or other organized root analysis  tools.

Phase 4-  Improve -  Once root causes is isolated,  which could be from multiple source,  then we generated improvement plan to counter the root causes  and check if improvement plan effective by collecting and analyze data and compare against data collected from measure phase.  The data will show improvement if the improvement plans are effective

Phase 5 -  Control, once we have improvement plans which effective to control variations,  then we will need document the actions taken for  standardization.  Then we will continue monitor the process to ensure improvement plan is sustainable.

Phase 6 -  Report all work done, some organizations  consider reporting is done in control phase, thus their 6 sigma phase is DMAIC

Special cause variations which are associated to changes in process sometimes could process improvement which is desirable or changes in unknown source which cause process to behave worse than before.  Our focus would be to eliminate this unwanted change (special cause) to ensure our process is behaving normally again.  We would need to use systematic problem solving approach such as corrective action approach 8- discipline approach, 5C methodology and 7 steps which I will write in details in my next article.

Attached is the table which compare both cause of variations in manufacturing process.

  

	Common cause	Specials causes
Strategy	Reduce	Eliminate
Source of variation	Already part of process input	Sudden change in process input
Common Tools used	6 sigma approach	8-D, corrective action, error proof, 5C, 7 steps problem solving, Kaizen
Time taken	Could be months	Days or  1-2 weeks
Application	Continuous improvement plan	Customer complaint, sudden change with reject rate spike

As the strategy to address both common cause and special cause variations is different , it would be fatal and costly to treat special cause variations as common cause variations vice versa. 

Unfortunately there are many manufacturers who does NOT know how to identify common cause and special cause variations when there is quality issue due to :-

• Manufacturer handle common cause as special cause issue when they did not realize common cause variation already exist during the start of new product manufacturing.  They are unable to detect the problem until their customer complaint.

• Manufacturer treat special cause as common cause variation when both causes exhibit same failure symptom.  For example cosmetic defect such as scratch always happen in mechanical parts which is a common cause variation.  If there  is a sudden high spike of the scratch reject symptom,  then we could have a special cause variation mix with common cause variations.  Common cause issue root cause could be natural variation contributed by process input as there are zero defect process which are non existence.  The high spike could be due to a single source problem where a new jig had caused scratch to the part. 

The mishandling of common and special cause are the reasons why some issue are NOT properly resolve.  Therefore the key to a consistent good quality product is to understand the type of variation that  is contributing to poor quality followed by improvement to address type variation from root cause.