Quality
Inspection, Quality Control, Quality Assurance, and Total Quality Management.
Shri Kanchan Biswas.
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1. QUALITY
The
term ‘Quality’ has different perceptions by different people and accordingly, there
are many and varied definitions of Quality. In a very broader sense, it can be defined
(as per Mil-Q-9858 – “Quality Assurance Engineering”):
a)
Quality is the totality of features that bears its
ability to satisfy a given need.
b)
Quality is conformance to a set of
requirements, if met, results in a product fit to use.
The term ‘Quality’ can relate to a product or
services rendered to a customer viz. both internal and external customers.
1.1
Inspection, Quality Control & Quality Assurance
Inspection – It is an activity by which Segregation of good
and bad products/services can be performed through either tests or measurements
or both.
Quality Control – It is all the measures taken to sustain the product or service
quality to a specified standard. The QC activities will include control over
men, machines, materials, and manufacturing processes.
Quality Assurance - The term, “Quality Assurance”
may be defined as a ‘guarantee’ to customers’
satisfaction through controls in design and manufacturing defects. The QA
embraces all activities and functions concerned with the attainment of quality. It
assures that all the QC measures taken are effective, guarantee quality, and is properly implemented.
1.2 Quality
Control & Quality Assurance
There are two views about the superiority between the QC and QA:
In North America and
Europe, ‘Quality Control’ is the overall system adopted for
ensuring quality. ‘Quality Assurance’ as a sub-system (of the
overall Quality Control System), provides proof that quality control processes
and procedures are in effect being followed properly.
In many other places ‘Quality Assurance’ is regarded as
embracing all activities and functions concerned with the attainment of
quality, rather than in the narrower sense only of the provision of proof
associated with the word “Assurance”. In this case ‘Quality Control’ is
regarded as a subsystem of the 'Quality Assurance' system. In this concept, QC essentially deals with
practical techniques adopted for the sustenance of the product quality as set out
in the product specification.
1.3 Total
Quality Management
Total Quality Management (TQM) is a management approach that seeks to provide long-term success by providing unparalleled customer satisfaction through the constant delivery of quality products and services. To properly execute TQM methods, the entire organization needs to operate as a single unit in the pursuit of excellence.
The seven pillars of
TQM are shown below:
1. Customer Focus - Give the highest focus
on the customer’s experience in all interactions with the organization. From
first contact through purchase and continued support, the customer should
always be the main priority.
2. Employee ownership - Involvement
of every team member to ensure that complete quality control is important at
every level. TQM doesn’t focus on a single department because the goal is to provide
customers with a great experience from every level of the organization.
3. Process-based – Create and implement processes
that provide the best products and have the ability to repeat them. Quantifying
success and defining the steps taken to get there are essential for the successful
implementation of TQM.
4. System integration - Use
every asset available to the company for maximum benefit. This is best achieved
through system integrations that combine disparate parts of the organization
into a single, well-oiled machine working in complete synergy.
5. Communication - Ensure
every team member is at their best and functions as a value-adding member
of that team. Communication and transparency at every level are core tenets
of successful TQM practices.
6. Data-driven – Don’t
make guesswork. Instead, use and leverage available data for the improvement of
the organization, and decisions are made based on quantifiable facts.
7. Constant improvement. TQM
is not a 'one-time activity'. Reaching 100% perfection is a goal and it must always be
pursued to get the organization as close to 100% perfection as possible.
1.4 Comparison
of Quality Assurance Processes
A comparison of the
various basic activities performed during Inspection, Quality Control, Quality Assurance, and TQM Processes is shown in table – 1.
Table – 1:
Comparison of Quality Assurance Processes
|
Inspection |
Quality Control |
Quality
Assurance |
Total
Quality Management |
|
Error Detection and Rectification |
-
Use
Statistical Methods -
Follow
Quality Standards -
Analyse
Process Performance and take action for improvement |
-
Consider
Quality Systems -
Consider
quality costing -
Use Problem-Solving
techniques -
Carry out
Quality Planning |
-
Inculcate
Quality culture over the whole Organisation
-
Consider
Quality as a strategy for competitive Business -
Provide Staff
Empowerment and involvement in Quality Problem Solving & Improvement -
Involve
Customers & Suppliers -
Aim Zero
Defect Program |
1.5 Growth of Quality
Engineering Discipline
In the early part of
the industrial growth, the manufacturers (often the artesian) used to be the
inspectors for their own products. With the growth of industrial activities, a
separate stream of technical branch emerged as ‘Inspectors’, who were assigned the
responsibilities of inspecting and segregating the good and bad products. With the increase in the quantity
of production, the industry saw a newer scheme of “Statistical Quality Control”
procedures. Since 1980 the concept of quality is changed as shown in table - 2.
Table – 2: Historical
Growth of Quality Assurance
|
1900s |
1940s |
1960s |
1980s |
Post-1990s |
|
Inspection |
Statistical Sampling |
Organisation Quality Focus |
Customer Driven Quality |
Quality Management System (QMS) |
|
Old Concept of
Quality
|
New
Concept of Quality |
International Professional
Quality Certification Bodies Monitor the Organisations’ QMS as per International Standards like ISO 9001, AS 9100, etc. |
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|
Inspect for Quality after Production |
Build
Quality into the process. Identify and correct causes of Quality Problems. |
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TQC: Total Quality Control; An UK Terminology TQM: Total Quality Management; Used in USA, Japan, and India |
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1.6 Quality Assurance Manual
Every organization should have a Quality
Assurance Manual. The Quality Assurance Manual Should contain the Policies of
the organization related to the following issues:
1)
Quality Policy of the Organisation
2)
Management Responsibilities
3)
Quality System being followed
4)
Design Control Procedures
5)
Procedure for Documentation and Data Control
6)
Purchase Procedure and Control
7)
Procedure for Control of Customer-Specified Product
8)
Manufacturing Process Control Procedure
9)
Inspection and Testing Procedure
10) Procedure for Control
of Non-Conformal Product
11) Procedure for
Calibration of Test and Measuring Equipment, Jigs, and Fixtures
12) Storage, Packing, and Preservation Procedures
13) Approval of Inspectors, welders, and the record thereon.
2. COST OF QUALITY
Quality has dramatic cost implications – dissatisfied
customers and consequently loss of business. The company has to pay a very high
cost for producing poor-quality goods and services.
2.1 Cost of Quality
Quality has two types of cost elements. These
are:
b) Quality Failure Cost.
Quality Control Cost
is the cost incurred to achieve and maintain high quality. It is like a business
investment. It has two elements viz: Prevention cost and Appraisal cost.
a) Prevention Cost -
all expenditures incurred with the aim of achieving high quality or
preventing the occurrence of poor quality.
These include -
1) Quality Planning Cost – Cost of developing
and implementing a quality plan.
2)
Data collection from customers to prepare customer-desirable
specifications.
3)
Cost of product and process design to meet customer requirements.
4)
Employee training in quality measurement.
5) Cost of maintaining records and data related to quality.
b)
Appraisal Cost – Appraisal costs are
incurred in the process of uncovering the defects. They include all costs
incurred to make sure that the Quality standards are met. These include all costs
towards the test and inspection during manufacture and failure analysis to get
the reason for failure and arrive at the remedial measures.
2) Product testing
3) Performance audits
4) Cost of equipment used for quality appraisal
5) Man-hours spent on measuring quality (QE)
2.1.2 Quality Failure Cost
Cost consequence of poor quality. These may be loss of ‘Company reputation/Goodwill’ as well as Loss
of Business. The quality failure
cost may be an external failure cost or an internal failure cost. These
are discussed below:
a) Internal Failure Cost
– Cost associated with poor quality before the product reaches the customers' site. This cost includes:
1) Rework Cost – Cost
for correcting the defective item
2) Scrap –
The defective item is beyond economical repair. (Loss of raw material, labour, machine
hour)
3) Cost of machine time for rejected parts
4) Salvage action cost.
b) External Failure Cost – the cost associated with
quality problems that occur at the customers' site. These costs are very damaging
particularly because customer faith and loyalty is difficult to regain. Some of
these cost elements will be:
2) Product Testing
3) Performance audit (like welders’ tests etc.)
4) Cost of equipment used for quality appraisal
5) Workers’ time spent measuring quality.
2.2 Discussion on Cost of Quality
Company should invest heavily in prevention and appraisal cost in order
to prevent internal and external failure costs. Earlier the defects are found,
less costly are to correct. Detecting and correcting cost during product design
and production is considerably less expensive than the defects are found at
customer site.
External failure cost tend to be particularly high for service sector organisations.
This is because with a service the customer spends much time in the service
delivery system and there are fewer opportunities to correct defects than there
are in manufacturing.
Example of external failure – an airline who has overbooked flights,
long delays in airline service and lost luggage. These will have a very long
time effect on the passengers.
Various elements of Cost of Quality is shown in figure -1. A comparison of various Quality Cost elements is shown at figure – 2.
Figure -1:
Elements of Cost of Quality
3. QUALITY ASSURANCE
FUNCTIONS
The QA functions during various stages of product life cycle is shown
below.
3.1. QA During
D&D (Design and Development) Stage
1)
Technical Requirement Identification
2)
Verify
Technical Specification Document
3)
Technical Specification Reviews
4)
Preliminary Design Document
5)
Preliminary Design Review
6)
Critical Design Document
7)
Critical Design Review
8)
Product Realisation Process.
3.2 QA During Procurement, Storage & Release for se
1) Establish acceptance
plan as part of the indents/RFQ
2) Participate in the
selection of sub-contractors/vendors.
3) Establish QA
procedures for storage and release of items with associated formats for recording
various data towards ensuring trace-ability.
4) Obtain decisions
on non-conformances and regularize them in consultation with regulatory
agencies.
5) Ensure compliance of
procedures for proper storage of accepted items in the bonded stores.
6) Establish
infrastructure for servicing and serviceability check
7) Inspection of storage facilities like cold storage for sealants, perishable/lived item like rubber seals, paints etc. and approve them for proper temp control etc.
3.3 QA During
Fabrication
1)
Approval of the
process sheets
2)
Preparations of inspection
plan documents (including inspection instructions)
3)
Qualification of
new processes, if any.
4)
Surveillance of
following functions of sub-contractors’ QC/QA of the Project team
5)
Evaluations and
surveillance of machines, fixtures, tools, installation and workroom, inspections
status and their approval etc.
6)
To Ensure
Periodic calibration of Jigs, Rigs, gauges etc.
7)
Perform
inspection and ensure effective documentation of inspection data.
8)
Obtain decision
on non-conformances, if any,
9)
Ensure that
proper segregation and identification of defective and downgraded items/
stores.
10)
Carryout analysis of recurring non-conformances and
suggest corrective actions
11)
Quality audit originated from compulsory surveillance
activities (regulatory functions) in the field of nuclear, space, military and
aeronautical industries. These audits were limited to inspection of product and
process conformity with reference to safety in view.
3.3 QA During Assembly
- 1) The assembly procedures should be documented by the QA team of subcontractor/ vendor.
- 2) A checklist bringing out the checks / inspection that will be carried out during Assembly will be prepared by the QA team and effective implementation of the same shall be ensured.
- 3) As part of the assembly document the list of items / parts along with their identification numbers, forming part of the said assembly shall be prepared, along with their inspection/test reports.
3.4 QA
During Qualification and Testing & Realisation of Deliverables
3.4.1 Qualification Testing
1) QA shall approve
the Qualification Test Plan and test procedure documents in
consultation with concerned RCMA.
2) The test facilities
shall be duly qualified/ validated for use by the QA (work center/ test center)
and approved.
3)
QA shall ensure approval of the test rig
by DGAQA as per the test rig specification
4)
QA shall participate during qualification tests
together with concerned certifying agencies.
5)
QA shall carry out post- test inspection and
prepare test report
6)
QA shall freeze all the documents such
as drawings, specifications, process sheets, acceptance procedures, inspection
plans, assembly procedures etc. to enable realisation of deliverables without
any change.
3.4.1 Qualification Testing
1) QA shall approve
the Qualification Test Plan and test procedure documents in
consultation with concerned RCMA.
2) The test facilities
shall be duly qualified/ validated for use by the QA (work center/ test center)
and approved.
3)
QA shall ensure approval of the test rig
by DGAQA as per the test rig specification
4)
QA shall participate during qualification tests
together with concerned certifying agencies.
5)
QA shall carry out post- test inspection and
prepare test report
6) QA shall freeze all the documents such as drawings, specifications, process sheets, acceptance procedures, inspection plans, assembly procedures etc. to enable realisation of deliverables without any change.
3.4.2
Acceptance Testing
Acceptance Test Plan and test procedure documents shall be scrutinized
& be approved by the concerned certifying agencies.
2) The test facilities
shall be duly qualified/ validated for use by the QA.
3) Failures, if any, should be duly
recorded and necessary actions towards failure analysis are to be
initiated in consultation with all concerned and corrective actions shall be
implemented.
4) QA shall ensure that each
of the deliverables shall be accompanied by the following documents:
a) History card / Log
card /Acceptance tag
b) Inspection report /
Release note
c) Provisional clearance
certificate
d) Acceptance test
reports
e) User and Maintenance
manual
f) Illustrated part list
/catalogue
3.5 QA During System Integration & Rig Tests
A sequential integration schedule and procedure shall be evolved
by the respective system designers.
1) QA shall Participate
during the integration of the sub-system on the test rig together with IV&V
(where S/w are already approved) to ensure proper sequence of integration;
perform inspection/checks as identified in the inspection plan document for
this activity.
2) QA shall participate
in the testing and ensure implementation of requirements laid down in the
relevant test plan.
3) QA shall approve
test rigs.
4) QA shall participate
in test results analysis.
5) QA shall ensure that the recommendations of Failure Analysis by Defect Investigation team are complied with.
3.6 QA Function
during Failure Reporting & Analysis
1)
In case of failure during testing and service
exploitation, the failures shall be appropriately recorded by the
quality assurance team.
2) A failure
analysis committee in the work/test center concerned shall have also
the representative of QA team of the work/test center as one of its members.
The failure analysis should identify the cause of failure and arrive at a
corrective action.
3) All the
corrective action is to be tracked and the implementation of
the same shall be ensured by QA.
4. QUALITY ASSURANCE FOR VENDOR
DEVELOPED ITEMS
4.1 Surveillance and Support
to Subcontractors
1) The QA shall carry out
surveillance and provide necessary support to the vendor.
2) QA shall maintain vendor
record and create mechanism for vendor rating.
3) QA shall maintain vendor
rating.
4) QA shall provide surveillance
and support to the vendor according to his rating.
4.2 QA during Hardware
Realization at Subcontractor’s Premises
1) Ensure quality and
maintainability aspects as per specifications.
2) Define clearly the
quality implementation mechanism to include,
-
Identification of applicable documents needed
-
Define the acceptance criteria
-
Define surveillance mechanism
-
Define the means to ensure traceability
-
Decisions on waivers, etc.
5. QMS AUDIT AND
CERTIFICATION
With the advent of
Quality Management System of the International Organisations for
Standardization (ISO), quality audit has become a requirement for competitive business
strategy. Similarly, the International Aerospace Quality Organisation (IAQG)
has released requirements for the Aerospace Quality Management Systems (AQMS).
Third party audits and certifications followed by annual surveillance audits
have been instituted by these international bodies for monitoring and
maintaining requisite quality standards by the client organisations.
Relevant International Standards:
•
ISO 9001: 2015 – Quality Management System requirement
•
ISO 14001: 2015 – Environmental Management System
•
SAE AS 9100D:2016 – Quality Management Systems –
Requirement for Aviation, Space
and Defense Organisation.
•
ISO 19011:2018 – Guide lines for Quality and /or Environmental Management system audit.
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