inspection and testing of quality in TQM

Unit: 2 Lecture: 12
Dr. Jayanta Kr. Mahato
Associate Professor
Mechanical Engineering Dept.
Inspection and testing of
quality

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-: Content :-
•Objective of Quality
•Process and Inspection
•Process Turtle diagram
•Process Control
•Inspection objective and
purpose
•Stages of inspection
•Methods of inspection
•Drawbacks of inspection
•Quality Cost
•Quality improvement

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-: Objective of Quality
:-
(1)To decide about the standard of
Quality of a product that is easily
acceptable to the customer.
(2) To check the variation during
manufacturing.
(3)To prevent the poor quality
products reaching to the customer.

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-: Process and Inspection :-
What is Process?
Ans: A series of actions or steps
taken in order to achieve a particular
product.
What is an inspection?
Ans: An inspection is the verification
of process/product quality to pre-
identified quality specifications
before, during or after the production
process.
Benefits of inspection: It helps to
control quality, reduces
manufacturing costs, eliminate scrap
losses and assignable causes of
defective work.

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-: Process Turtle Diagram :-
PROCESS
NAME/DESCRIPTION:
What steps are involved in the
process?
What happens at each step in the
process?
What documents and records are
generated?
Is the process implemented in
accordance with procedures,
instructions or plans?
Are controls applied as described?
PROCESS INPUTS:
What triggers the process?
What inputs are required?
Where do the inputs come from?
Are they received in a timely
manner?
Are they fit for purpose?
PROCESS OUPUTS:
What is the product produced by this
process? Are product measures in
place to ensure that product meets
requirements? How are processes
measured? Are product and process
measures achieved?
What feedback is received from
customers?
EQUIPMENT & FACILITIES:
What equipment and resources are
required?
Is equipment suitable and properly
maintained?
Is the work environment maintained?
Is there evidence of appropriate
maintenance of all equipment used by
this process?
INSTRUCTIONS &
PROCEDURES:
Review the documents that
describe and control the process.
Review all the important steps and
activities of the process being
audited. This info must be
documented. Evaluate how
effectively the process flows
through the steps.
Do you see roadblocks or issues?
SUPPORT PROCESSES:
As you audit, you will see how it
connects and interacts with other
processes. Interactions with other
processes are always important. Audit the
relevant links to related processes and
support processes.
KEY PERFORMANCE
INDICATORS:
Review metrics and performance with
Managers, Supervisors and operators.
They should know how things are
running, objectives, customer issues,
problem areas. If they do not, the
requirements were not met. Is there
evidence that quality objectives and
targets affected by this process are
being achieved?
PERSONNEL:
Review employee skill lists for the
process.Are there lists of skills for each
position? Do they show enough detail?
This is often a finding, where lists are
generic with inadequate detail. Training
is a key process of any system.Are there
particular skills you want to evaluate?
CONTROL PROCESSES:
How is the process defined and who
is responsible? How are customer
requirements defined? What
specifications apply defined?
What objectives and targets apply
process? What controls/check points
are there?
What acceptance criteria exist?

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Process Control
(6) Taking action, if any, on the
difference.
• Process Control: The process through which the standards are
established and met with standards is called Process Control.
The control process involves a
universal sequence of steps as
follows :
(1)Choose the control subject and
unit of measure.
(2) Set a standard value i.e., specify
the quality characteristics
(3)Choose a sensing device which
can measure.
(4) Measure actual performance.
(5)Interpret the difference between
actual and standard.

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Factors Affecting Product Design

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-: Inspection objectives and Purpose :-
Objectives of Inspection
(1) To collect information regarding
the performance of the product
with established standards for the use
of engineering production,
purchasing and quality control etc.
(2) To sort out poor quality of
manufactured product and thus to
maintain standards.
(3) To establish and increase the
reputation by protecting customers
from receiving poor quality
products.
(4) Detect source of weakness and
failure in the finished products

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-: Inspection objectives and Purpose :-
Purpose of Inspection
(1)To distinguish good products
from bad products
(2) To determine if the process is
changing.
(3) To determine if the process is
approaching the specification limits.
(4) To rate quality of product.
(5) To rate accuracy of inspectors.
(6) To measure the precision of
measuring instrument.
(7) To secure products – design
information.
(8) To measure process capability.

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-: Types of Quality Inspection :-
4 types of inspection in quality control:
 Pre-production Inspection
 During Production Inspection
 Pre-shipment Inspection and
 Container Loading/Unloading Inspections

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 Pre-production Inspection: It is conducted before the production
process begins and helps to assess the quantity and quality of the
raw materials and components and whether they conform to the
relevant product specifications.

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 During Production Inspection: It is a quality control inspection
conducted while production is underway. This step is particularly
useful for products that are in continuous production and have
strict requirements and/or when quality issues have been found
prior to manufacturing during an earlier PPI

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 Pre-Shipment Inspection: These are important step in the quality
control process and the method for checking the quality of goods
before they are shipped. It ensures that production complies with
the specifications of the buyer. It is conducted on finished products
when at least 80% of the order has been packed for shipping.
Random samples are selected and inspected for defects against
the relevant standards and procedures.

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 Container Loading/Loading Supervision (LS): It ensure your
products are loaded and unloaded correctly. Inspectors will
supervise throughout the whole process and ensure your products
are handled professionally to guarantee their safe arrival to their
final destination.

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 Piece-by-Piece Inspections: It involves checking each and every
item to evaluate a range of variables including general appearance,
workmanship, function, and safety. This inspection process can be
carried out either before or after the packaging inspection. In the
circumstance where the goods require particular attention to
ensure compliance to specification or when the goods are high-
value, a 100% inspection service should be performed.

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-: Stages of Inspection :-
(1) Inspection of incoming
materials: It is also called receiving
inspection. It consists of inspecting
and checking of all the purchased
raw materials and parts that are
supplied before they are taken on to
stock or used in actual
manufacturing. Inspection
may take place either at supplier’s
end or at manufacturer’s gate. If the
incoming materials are large in
quantity and involve huge
transportation cost it is economical
to inspect them at the place of
vendor or supplier.

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(2)Inspection of production process:
The work of inspection is done while
the production process is
simultaneously going on. Inspection is
done at various work centers of men
and machines and at the critical
production points. This is having
advantage of preventing wastage of
time and money on defective units and
preventing delays in assembly.
(3)Inspection of finished goods: This
is the last stage when finished goods are
inspected and carried out before
marketing to see that poor quality
product may be either rejected or sold at
reduced price.

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1) 100% Inspection:
This type will involve careful inspection in
detail of quality at each strategic point or
stage of manufacture where the test involved
is non-destructive and every piece is
separately inspected. It requires more number
of inspectors and hence it is a costly method.
There is no sampling error. This is subjected
to inspection error arising out of fatigue,
negligence, difficulty of supervision etc.
Hence complete accuracy of influence is
seldomly attained.
It is suitable only when a small number of
pieces are there or a very high degree of
quality is required. Example : Jet engines,
Aircraft, Medical and Scientific equipment.

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2) Sampling Inspection:
In this method randomly selected samples
are inspected. Samples taken from different
batches of products are representatives. If
the sample prove defective, the entire
concerned is to be rejected or recovered.
Sampling inspection is cheaper and quicker.
It requires less number of Inspectors. Its
subjected to sampling errors but the magnitude of
sampling error can be estimated. In the case of
destructive test, random or sampling
inspection is desirable. This type of inspection
governs for automatic machines which are less
susceptible to chance variable and hence require
less inspection, suitable for inspection of products
which have less precision importance and are less
costly.

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-: Drawbacks of Inspection :-
(1) Inspection adds to the cost of the product
but not for its value.
(2)It is partially subjective, often the inspector
has to judge whether a product passes or not.
Example : Inspector discovering a slight burnish
on a surface must decide whether it is bad or it
can fit.
(3) Fatigue and Monotony may affect any
inspection judgment.
(4)Inspection merely separates good and bad
items. It is no way to prevent the production
of bad items.

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-: Quality Cost :-
(A) Failure costs :-
1) Internal failure costs:- They include,
a) Scrap : The net loss in labor and material resulting from
defectives which cannot economically be repaired or used.
b) Rework : Cost of defect correction to make them fit for use.
c)Retest : The cost of inspection and retest of products that
have undergone rework or other revision.
d)Down time : The cost of idle facilities resulting from defects.
(Example : Printing press down due to paper break).
e) Yield losses : The cost of process yield lower that might be
attainable by improved controls. Includes ‘‘overfill’’of containers
(going to customers) due to variability in filling and measuring
equipment.

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-: Quality Cost :-
2) External failure costs:- They includes,
a)Complaint adjustment : All costs of
investigation and adjustment of justified
complaints attributable to defective product
or installation.
b)Returned material :All costs associated
with receipts and returned from the field.
c)Warranty charges :All costs involved in
service to customers under warranty
contracts.
d)Allowances : Costs of concessions made
to customers due to substandard products
being accepted by the customer as is include
loss in income due to down grading products
for sale as seconds.

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-: Quality Cost :-
(B)Appraisal Costs: These costs include,
a)Incoming material inspection: The cost of
determining the quality of vendor/supplier made
products by inspection on receipt or at source.
b)Inspection and test: The cost of checking the
conformance of the product throughout its
progression, in the factory, including final acceptance
and check of packing.Also includes testing done at
customer’s premises prior to giving up the product to
the customer.
c)Maintaining accuracy of test equipment: Includes
the cost of operating the system that keeps the
measuring instruments and equipment in calibration.
d)Materials and services consumed: Includes costs
of product consumed through destructive tests,
materials consumed and services where significant.
e) Evaluation of stock: Include the costs of testing
products in field storage or in stock to evaluate

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-: Quality Cost :-
(C) Prevention Costs: It includes :
a)Quality Planning: This includes the broad array of
activities which collectively create quality plan, the
inspection plan, reliability plan, data system and
numeric specialized plans. It includes also preparation
of the manuals and procedures needed to communicate
these plans to all concerned.
b)New Product review: Includes preparation of bid
proposals evaluation of new design, preparation of test
and experiment programs and other quality activities
associated with the launching of new designs.
c)Training: The costs of preparing training programs
for attaining and improving quality performance
includes the cost of conducting formal training
programs as well.
d)Process control: Includes that part of process
control which is conducted to achieve fitness for use as
distinguished from achieving productivity, safety etc.

inspection and testing of quality in TQM

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inspection and testing of quality in TQM