Transcript inspection ppt

BY
AMAR P. NARKHEDE
INTRODUCTION
All the items raw materials, bought out items ,sub part ,
components are purchased from outside suppliers as
well as those manufactured at the home plant must be
verified for quality before passing them for next
operation. This ensures that
 Only acceptable pieces go to the next operation which
guarantees specified outgoing quality to the customer
 Defective pieces are withheld and additional cost is
prevented from being expanded on the defective
pieces
 Causes for the defectiveness are known to those
concerned and appropriate action is taken to prevent
re-occurrence of such defects
Inspection of incoming material serves other objectives
 It exerts moral pressure on the suppliers to inspect
goods before supply
 It enables buyer to assess suppliers quality assurance
capability and thereby decide future share of business
to the suppliers
 The inspection results enable buyer to discuss defects
with the suppliers, extracts promise to improve, watch
their performance in the subsequent suppliers, and
remove those who fail to show improvement event
after repeated promises
 Periodical feedback is also very important its aims to
good quality of the product
TYPES OF INSPECTION
 Cent percent inspection
 Sampling inspection
A.CENT PERCENT INSPECTION
It is one wherein each and every piece is verified
against the preset specifications. However, cent
percent inspection does not mean verification of each
and every quality characteristics. Only important
characteristics those necessary for satisfactory
performance of the function may be verified
WEAKNESS OF CENT PERCENT
INSPECTION
 It involves huge costs and expenditure incurred on
inspection which is a DEAD WEIGHT COST
(Inspection does not add any value to the product but
adds to the cost)
 It is time consuming and tedious
 It is not suitable for items whose conformance to the
quality specifications needs to be ascertained from
defective tests
 Cent percent inspection is not fool proof either. Since
inspection work is highly repetitive and boring, even
competent inspectors sometimes reject good pieces or
accept defective ones
An alternative to cent percent inspection is to use
statistical inspection methods wherein the quality of
the lot is decided based on the inspection results of
few pieces drawn from each consignment lot. If the
sample conforms to specifications, the whole lot is
accepted otherwise it is rejected. Since acceptance is
based on the interface drawn from the sample, the
technique is known as acceptance sampling
SAMPLING INSPECTION
 It is subjected to sampling errors as there is always a
chance that the sample may not be the true representative
of the population from which it is drawn. This at times my
cause acceptance of a lot of bad quality or rejection of a
lot of good quality
 Sampling errors is acceptance sampling are minimized by
selecting a sample which is true representative of the lot
(choosing the sample at random so that every portion of
the lot will have equal representation in the sample) such a
sampling is known as random sampling. If the sample is
true representative of the lot then only a few good
sampling plans exactly do this. A carefully designed
sampling plan utilizing appropriate sample size(n) and
allowable number of defectives called acceptance
number(c) usually takes care of quality assurance function
Acceptance sampling plan is a set of rules which
prescribe the procedure to be adopted in preparing the
lot, selecting the samples, conducting inspection of
the samples and fixing criteria for acceptance or
rejection of the lot
BASIS OF SAMPLING INSPECTION
 Variable basis (on the basis of actual measurements
like weight of packet in kgs, length of component in
mm, cm,meter, life test of part in hours
 Attributes basis (on the basis on “go” and “no go” i.e.
determining whether or not the product in the sample
conforms to the specifications for example pressure
gauge is either checked or not checked, furniture has a
desired color or it has not. Appearance surface
finished of cover is either satisfactory or not
NEED OR IMPORTANCE OF INSPECTION
 To sort out acceptable from defective raw material or
work in progress. This may be called remedial
inspection
 To help in locating the causes of defective work and
extend cooperation and assistance in removing these
causes. It is preventive inspection
 To control the quality standards of manufacturing
processes
 To submit reports to the management regarding
a. Quality of product manufactured
b. Quality of raw material received
c. Efficiency of plant operation
FUNCTIONS OF INSPECTION
 Raw material inspection
 Process inspection (machines, handling equipments)
 Tool inspection
 Finished Goods inspection( to control quality, quantity
small matters like colour, surface, shape)
QUALITY CONTROL
 QC is one of the important function of the
management. It is a system set of tools and techniques
by which products are made to comply with the
specifications at the minimum costs of the firm
 According to Alford and Beaty
“Quality Control is the mechanism by which products
are made to measure up to the specifications
determined from customer’s demand and transformed
into engineering and manufacturing requirements. It
is concerned with making things right than
discovering and rejecting those made wrong”
BASIC ASPECTS OF QULITY CONTROL
 Acceptance function: it is inspection of goods that
they are up to the specifications thereby segregate and
reject those which are defective it is called as
Inspection and it includes elements like receiving
inspection, process inspection, finished goods
inspection
 Preventive inspection: it refers to identification of
defects in materials thereby avoiding or minimizing
occurrence of defectives it includes elements like
capability study, failure statistics analysis, methods
studies
 Assurance function: it refers to verification that every
quality characteristic or a product is assured to meet a
predetermined performance standard at each stage in
manufacturing cycle it includes the elements like
customers complaints, quality audit, quality
determination, accuracy of inspection, executive
reports on quality
INSPECTION AND QUALITY CONTROL
INSPECTION
QUALITY CONTROL
 It is the art of comparing materials,
 Quality control is a industrial
products or performance with
established standards. It is the
process of measuring the qualities
of a service in terms of established
standards
 Inspection is one of the important
step in quality control
 The maintenance department is
responsible for inspection of plant,
machinery and equipment
 It includes Raw material
inspection, process inspection,
tools inspection, finished good
inspection
management technique or group of
techniques by means of which
products of uniform acceptable
quality are manufactured
 Quality control is not step in
inspection
 QC is department responsible for
various quality control activities
 It covers Inspection and statistical
Quality control
STATISTICAL QUALITY CONTROL
Statistics is the collection, organization, analysis and
interpretation of the data. The body of knowledge of
statistical methods is an essential tool of the modern
approach to quality. The increased precision
demanded of manufactured parts and product require
better methods to measure, specify and record it,
statistics, the science of the most valuable techniques
used in quality control jobs
The statistical techniques and methodology have
become more and more widely used got acceptability
in industries. The availability of power of computers
and advanced data processing equipments have
enhanced
FOUR STATISTICAL TOOLS USED IN QC
 Frequency Distribution
 Control charts
 Sampling methods
 Special methods (Profitability paper graphing, testing
of hypothesis, design of experiments)
The understanding of these tools is necessary for full
technological comprehension of quality control.
Because the statistical techniques are used in
controlling quality, it is called Statistical Quality
Control
THANK YOU