quality control methods

1. Quality Control methods and Measurement
systems specification limits and control
limits

2. Specific Learning Objectives(SLO)
• To learn about the quality control
• To list out the Methods of quality control
• To describe the difference between specification limits and
control limits

3. Quality
Definition
Quality as “the totality of features and characteristics of a
product or service that bears on its ability to meet a stated or
implied need”
ISO 8402 [ISO, 1986]
Meaning of Quality
Quality is the degree to which an object or entity (e.g.,
process, product, or service) satisfies a specified set of attributes
or requirements. The quality of something can be determined by
comparing a set of inherent characteristics with a set of
requirements.

4. Quality Control
Definition
Quality Control is the process through which we
measure the actual quality performance, and compare it with the
set standards and if there is a deviation then we take corrective
actions. Therefore, it is a reactive process.
Quality control can be defined as the devices, tools,
and skills through which quality activities are carried out.
Meaning
Quality Control is a systematic control of various
factors that affect the product quality. It depends on 4M
conditions i.e. Man, Machine, Material, and Method or working
conditions and Measuring instruments, etc.

5. Quality Control

6. Function of Quality Control
• It is an integral and permanent part of management control since
it minimizes the waste, reduces the cost, builds up goodwill of the
product and facilities advertising and sales.
• The concept of product or service quality is, however a relative
matter in terms of the price that people one willing to pay.
• In this sense, the quality of item refers to the ability of a product
to satisfy its intended purpose in relationship to the price.

7. • Quality control can be applied at two distinct phase of
operation
• Control of an operation in process and Inspection of raw
materials, semi finished products and finished products.
• The first phase of quality control is carried out by Statistical
Quality control
• While second phase is done through Inspection control

8. Quality Control logo

9. Quality Control Methods
The Techniques of quality are discussed under three methods
 Inspection
 Statistical Quality Control (SQC)
 Quality Circle (QC)

10. Inspection
• Inspection involves checking the product so that it conforms to
establish standard in appearance, performance, weight, packaging
and etc.
• The inspection department will have to decide What to Inspect,
How to inspect, How much to inspect and Where to inspect.
• The product may be inspected by looking at them, Measuring
them or Testing them.
• It helps both in Removing the non conforming products from
Inventory.
• But also stops further Production of imperfection items.

12. Statistical Quality Control (SQC)
• The SQC is the procedure for the control of the quality of the
products by application of the Theory of probability to the
results of Examination of samples.
• Thus it is concerned with the problem of how many items of
larger number should be inspected to determine a probability that
total number conforms to quality standard.
• With SQC manager can determine the probability of sample’s
reliability.

13. Quality Circle (QC)
• Quality circle is a group of employees that meet regularly to
solve problems affecting its work area.
• This group carries on continuously as a part of organization -
wide control activities, self development, mutual development,
control and also improvement within the workplace utilizing qc
techniques with all member participating.
• Generally six to twelve volunteers from same work place make
up the circle.

14. • The members receive training in problem solving, SQC and
group process.
• QC generally recommends solution for Quality and
Productivity problems which may be implemented by the
management.

15. Specification Limits
Specification limits are the targets set for a product or the process
by customer or market performance; often, Voice of the Customer
is the input for customer specification limits. In other words, it is
the intended result of the metric that we measure.

16. Control Limits
Control limits are the horizontal lines in a control chart that
delineate the upper and lower limits of the acceptable range of
results for a process. When plotted data exceeds a control limit, it
indicates that a process is out of control, and requires
management attention.

18. Difference between Specification limits
and Control Limits

25. -LEKHA.S
KEERTHANADEVI.S