POM Notes for Cycle Test (1)
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Transcript of POM Notes for Cycle Test (1)
SRM UNIVERSITY
RAMAPURAM CAMPUS
DEPARTMENT OF MANAGEMENT
STUDIES
Study Material
MBN 510 - Production and Operations
Management
CONTENTS
UNIT - 1
Chapter1 - Overview of Production Management
Chapter 2 - Production System
UNIT – II
Chapter 1 - Product Design
Chapter 2 – Process planning
Chapter 3 – Make or Buy Decisions
Chapter 4 – Modern production management
( CAD,CAM)
UNIT - III
Chapter 1 – Production Planning & Control
Chapter 2 - Demand Forecasting
Chapter 3 – Plant location
Chapter 4 – Plant Layout
Chapter 5 - Capacity planning
Chapter 6 - Inventory control
UNIT – IV
Chapter 1 - Quality Control
By
Mrs.VIJAYA RANI ANANDAN, MBA., M.Phil., (Ph.D).,
Assistant Professor (OG)
Department of Management studies
SRM University
Ramapuram Campus.
Chapter 2 – Work Study ( method study/ time Study/
Work measurement)
UNIT – V
Chapter 1 – Maintenance Management
Chapter 2 – Purchasing
Chapter 3 – Store Keeping
Unit - 1
Chapter - 1
Overview of Production Management
Synopsis
Meaning of POM
Scope of POM
Objectives of POM
Functions of POM
Factors affecting POM
POM relation with other functional areas
MEANING OF PRODUCTION
Production is an intentional act of producing something
in an organized manner. It is the fabrication of a physical
object through the use of men, material and some function
which has some utility e.g. repair of an automobile, legal
advice to a client, banks, hotels, transport companies etc.
The main inputs are materials, Machines, Men ( Labour),
Money and Methods.
INPUTS PROCESS
OUTPUT
Goods & services
Transformation
Materials
Machines
Men
Money
Production and operations management (POM) is
the management of an organization’s production
system.
• A production system takes inputs and converts them
into outputs.
• The conversion process is the predominant activity of a
production system.
• The primary concern of an operations manager is the
activities of the conversion process.
MEANING OF PRODUCTION MANAGEMENT
A few definitions of production management are being
reproduced here under to understand the meaning of the term
clearly:
“Production management is the process of effectively
planning and regulating the operations of that part of an
enterprise which is responsible for actual
transformation of materials into finished products”.
Elwood S. Buffa has defined the term in a broader sense as:
“Production management deals with decision making
related to production process so that the resulting goods
or services are produced according to specifications, in
amounts and by the schedules demanded and at a
minimum cost”.
SCOPE OF PRODUCTION MANAGEMENT
Specifying and accumulating the input resources, i.e.,
management, men, information, materials, machine and
capital.
Designing and installing the assembling or conversion
process to transform the inputs into output, and
Coordinating and operating the production process so
that the desired goods and services may be produced
efficiently and at a minimum cost.
FUNCTIONS OF PRODUCTION MANAGEMENT
a) Product selection and design: the product mix marks
the production system either efficient or inefficient.
Choosing the right products keeping the mission and
overall objective of the organization in mind is the key
to success. It is the design of the product, which makes
the organization competitive or noncompetitive.
b) Activities relating to production system designing:
decision related to the production system design is one
of the most important activities of the production
management. This activity is related to production
engineering and includes problems regarding design of
tools and jigs, the design, development and installation
of equipment and the selection of the optimum size of
the firm. All these areas require the technical expertise
on the part of the production manager and his staff.
c) Facilities location: the selection of an optimum plant
location very much depends upon the decision taken
regarding production engineering. A wrong decision
may prove disastrous. Location should as far as
possible cut down the production and distribution cost.
There are diverse factors to be considered for selecting
the location of a plant.
d) Method study: the next decision regarding production
system design concerns the use of those techniques,
which are concerned with work environment and work
measurement. Standard method should be devised for
performing the repetitive functions efficiently.
Unnecessary movements should be eliminated and
suitable positioning of the workers for different
processes should be developed. Such methods should
be devised with the help of time study and motion
study. The workers should be trained accordingly.
e) Facilities layout and materials handling: plant layout
deals with the arrangements of machines and plant
facilities. The machine should be so arranged that the
flow of production remains smooth. There should not
be overlapping, duplication or interruption in
production flow. Product layout where machines are
arranged in a sequence required for the processing of a
particular product, and process layout, where machines
performing the similar processes are grouped together
are two popular methods of layout. The departments are
layout in such a way that the cost of material handling
is reduced. There should be proper choice of material
handling equipment.
f) Capacity planning: This deals with the procurement of
productive resources. Capacity refers to a level of
output of the conversion process over a period of time.
Full capacity indicates maximum level of output.
Capacity is planned for short-term as well as for long
term. Process industries pose challenging problems in
capacity planning, requiring in the long run, expansion
and contraction of major facilities in the conversion
process.
Tools for capacity planning are marginal costing (Break
Even Analysis), learning curves, linear
programming, and decision trees.
g) Production planning: the decision in production
planning include preparation of short-term production
schedules, plan for maintaining the records of raw
materials, finished and semi-finished stock, specifying
how the production resources of the concern are to be
employed over some future time in response to the
predicted demand for products and services
h) Production control: after planning, the next
managerial production function is to control the
production according to the production plans because
production plans cannot be activated unless they are
properly guided and controlled.
“Production control is the process of planning
production in advance of operations; establishing the
exact route of each individual item, part or assembly;
setting, starting and finishing dates for each important
item, assembly and the finished products; and releasing
the necessary orders as well as initiating the required
follow-up to effect the smooth functioning of the
enterprise.
i) Inventory Control: inventory control deals with the
control over raw-materials, work-in-progress, finished
products, stores, supplies, tools, and so is included in
production management. The raw materials, supplies
etc should be purchased at right time, right quality, in
right quantity, from right source and at right price.
PRODUCTS VERSUS SERVICES
The output is spoken as a “bundle of products and
services” . The line between product & services is not
necessarily always clear. Nevertheless, there are important
differences between them. Products are tangible things that we
can carry away with us, where as services are intangible and
perishable and are consumed in the process of their production.
Products may be produced to inventory and made available “
off-the-shelf” whereas the availability of the services requires
keeping the productive system that produces them in readiness
to produce the services, as they are needed. In addition the
person being served often participates in the productive
process. In product systems, there is very little if any, contact
between the producers and consumer.
PRODUCTS SERVICES
Tangible
Can be produced to inventory
for-off the- shelf” availability
Minimal contact with ultimate consumer
Complex and interrelated processing
Demand on productive systems variable on weekly, monthly, and seasonal basis
Markets served by productive system are regional, national and international
Large units that can take advantage of economies of scale
Intangible and perishable; consumed in the process of their production
Availability achieved by keeping the productive system open for services
High contact with clients or customers
Simple processing
Demand commonly variable onhourly, daily and weekly bases .
Markets served by productive system are usually local
Relatively small units to serve local markets
Location dependent on location of local customers, clients and users
OBJECTIVES OF PRODUCTION/ OPERATIONS
MANAGEMENT
Every system (or organization) has a purpose, certain
objectives & goals to achieve since the objectives of an
organization have hierarchical structure, sub-goals lead to
accomplishment of goals, which contribute, to the achievement
of objectives and eventually the purpose or mission of an
organization .It is very important that these objectives should
be unambiguously identified, properly structured and explicitly
stated.
In general terms, the objectives of an organization may be to
produce the goods/or services in required quantities and of
right quality as per schedule and at a minimum cost.
Thus quantity, quality and time schedule are the objectives that
determine the extent of customer satisfaction. If an
organization can provide for these at a minimum cost then the
value of goods created or services rendered enhances and that
is the only way to remain competitive. Thus various objectives
can be grouped as- performance objectives and cost objectives.
I. Performance Objectives
The performance objectives may include:
a) Efficiency or productivity expressed as output per
unit of input.
b) Effectiveness: It concerns expressed whether a right set
of outputs is being produced. Where efficiency may
refer to “doing things right”, effectiveness may mean
“doing the right things”.
c) Quality: Quality is the extent to which a product or
service satisfies the customer needs. The output has to
conform to quality specifications laid down before it
can be accepted
d) Lead times: Manufacturing lead-time or throughput time is the time
elapsed in the conversion process? Minimization of idle time, delays,
waiting etc. will reduce throughput time.
e) Capacity utilization: Percentage utilization of
manpower, machines etc. is calculated in order to
enhance overall capacity utilization.
f) Flexibility: If the conversion process has the flexibility
of producing a combination of outputs, it is possible to
satisfy a variety of customer needs.
II. Cost objectives
Attaining high degree of customer satisfaction on performance
front must be coupled with lower cost of producing the goods
or rendering a service. Thus cost minimization is an important
systems objective. Costs can be explicit or implicit. These
could be tangible in economic terms or intangible in social cost
terms- such as delayed supplies, customer complaints etc.
While managing production systems we must consider the
visible and invisible, tangible and intangible costs some
examples of these costs are:
Direct and Indirect labour cost
Scrap/rework cost
Maintenance cost
Cost of carrying inventory
Cost of stock outs, storage, back-logging, lost
sales
Cost of delayed deliveries
Cost of material handling
Cost of inspection and Opportunity cost
For the purpose of managerial decision-making, we
should consider the total relevant systems costs
including visible and invisible. A longer term cost
implication rather than only short-term will help in
arriving at better decision.
Types of Production system
Continuous Production Intermittent Production
Batch Production
Assembly line ProductionProcess Productionpr
Job Production
Mass production ( Flow)
POM RELATION WITH OTHER FUNCTIONAL AREAS
1.Human Resource - Recruit people ( Labour) for production
Department activities.
2. Finance – Allocation Funds ( Money) for production
department ( for purchasing land , machinery, materials ect.,)
3.Marketing Department – Making demand forecasting,
customer satisfaction, marketing research etc.,
Unit – I
Chapter – 2
Production system Analytical Synthetic
TYPES OF PRODUCTION SYSTEM
According to Webster, “System is a regular interacting
inter-dependent group of items forming a unified whole”. A
system may have many components and variation in one
component is likely to affect the other components of the
system e. g. change in rate of production will affect inventory,
overtime hours etc. Production system is the framework within
which the production activities of an organization are carried
out. At one end of a system are inputs and at the other output.
Input and output are linked by certain process or operations or
activities imparting value to the inputs. These processes,
operations or activities may be called production system. The
nature of production system may differ from company to
company or from plant to plant in the same firm.
ELEMENTS OF PRODUCTION SYSTEM
(1) Inputs
(2) Conversion process
(3) Outputs
(4) Storage
(5) Transportation
(6) Information
TYPES OF PRODUCTION SYSTEMS
There are two main types of production systems
(1) Continuous system
(2) Intermittent system
I. CONTINUOUS OR FLOW SYSTEM : According to
Buffa, “Continuous flow production situations are those where
the facilities are standardised as to routing and flow since
inputs are standardised. Therefore a standard set of processes
and sequences of process can be adopted”. Thus continuous or
flow production refers to the manufacturing of large quantities
of a single or at most a very few varieties of products with a
standard of processes and sequences. The mass production is
carried continuously for stock in anticipation of demand.
CHARATERISTICS OF CONTINUOUS OR FLOW
SYSTEM:
The volume of output is generally large (mass
production) and goods are produced in anticipation
of demand.
The product design and the operations sequence are
standardised i.e. identical products are produced.
Special purpose automatic machines are used to
perform standardized operations.
Machine capacities are balanced so that materials
are fed at one end of the process and finished
product is received at the other end.
Fixed path materials handling equipment is used
due to the predetermined sequence of operations.
Product layout designed according to a separate line
for each product is considered.
MERITS OF CONTINUOUS OR FLOW SYSTEM:
The main advantage of continuous system is that work
in progress inventory is minimum.
The quality of output is kept uniform because each
stage develops skill through repetition of work.
Any delay at any stage is automatically detected.
Handling of materials is reduced due to the set pattern
of production line. Mostly the materials are handled
through conveyer belts, roller conveyers, pipe lines,
overhead cranes etc.
Control over materials, cost and output is simplified.
The work can be done by semi- skilled workers because
of their specialisation.
DEMERITS OF CONTINUOUS OR FLOW SYSTEM :
Continuous system, however, is very rigid and if there
is a fault in one operation the entire process is
disturbed.
Due to continuous flow, it becomes necessary to avoid
pilling up of work or any blockage on the line.
Unless the fault is cleared immediately, it will force the
preceding as well as the subsequent stages to be
stopped.
Moreover it is essential to maintain stand-by
equipments to meet any breakdowns resulting in
production stoppages.
Thus investments in machines are fairly high.
TYPES OF CONTINUOUS PRODUCTION SYSTEM
(A) MASS PRODUCTION : Mass production refer to the
manufacturing of standardized parts or components on a large
scale. Mass production system offers economies of scale as the
volume of output is large. Quality of products tend be uniform
and high due to standardized and mechanization. In a properly
designed and equipped process, individual expertise plays less
prominent role.
(B) PROCESS PRODUCTION : Production is carried on
continuously through a uniform
and standardized sequence of operations highly sophisticated
and automatic machines are used. Process production is
employed in bulk processing of certain materials. The typical
processing industries are fertilizers plants, petrochemical
plants and milk diaries which have highly automated systems
and sophisticated controls. They are not labour–intensive and
the worker is just an operator to monitor the system and take
corrective steps if called for. On the basis of the nature of
production process, flow production may be classified in
Analytical And Synthetic Production .
In Analytical Process production, a raw material is
broken into different products e. g. crude oil is analysed into
gas, naptha, petrol etc. Similarly, coal is processed to obtain
coke, coal gas , coaltar etc..
Synthetic process of production involves the mixing of
two or more materials to manufacture a product for instance,
lauric acid, myristic acid, stearic acid are synthesised to
manufature soap.
(C) Assembly lines : Assembly lines a type of flow
production which is developed in the automobiles industry in
the U.S.A. A manufacturing unit prefers to develop and employ
assembly line because it helps to the efficiency of production.
In an assembly line, each machine must directly receive
materials from the previous machine and pass it directly to the
next machine. Machine and equipment should be arranged in
such a manner that every operator has a free and safe access to
each machine. Space should be provided for free movement of
fork lifts, trucks etc. which deliver materials and collect
finished products.
II.INTERMITTENT PRODUCTION SYSTEM
ACCORDING TO BUFFA, “Intermittent situations are
those where the facilities must be flexible enough to enough to
handle a variety of products and sizes or where the basic nature
of the activity imposes change of important characteristics of
the input (e.g. change in the product design). In instances such
as these, no single sequence pattern of operation is appropriate,
so the relative location of the operation must be a compromise
that is best for all inputs considered together”. In the industries
following the intermittent production system, some
components may be made for inventory but they are combined
differently for different customers. The finished product is
heterogeneous but within a range of standardized options
assembled by the producers. Since production is partly for
stock and partly for consumer demand, there are problems to
be met in scheduling, forecasting control and coordination.
CHARACTERISITICS OF INTERMITTENT
PRODUCTION SYSTEM :
The flow of production is intermittent, not
continuous.
The volume of production is generally small.
A wide variety of products are produced.
General purpose, machines and equipments are used
so as to be adaptable to a wide variety of operations.
No single sequence of operations is used and
periodical adjustments are made to suit different
jobs or batches.
Process layout is most suited.
Intermittent system is much more complex than
continuous production because every product has to be
treated differently under the constraint of limited resources.
Intermittent system can be effective in situation which
satisfy the following conditions:
The production centers should be located in such a
manner so that they can be handle a wide range of
inputs.
Transportation facilities between production centers
should be flexible enough to accommodate variety
of route different inputs.
It should be provided with necessary storage
facility.
TYPES OF INTERMITTENT PRODUCTION.
(A) JOB PRODUCTION : job production involves
the manufacturing of single complete unit with the use of a
group of operator and process as per the customer’s this is a
“ special order” type of production. Each job production or
product is different from the other and no repetition is
involved. The product is usually costly and non-
standardized. Customers do not make demand for exactly
the same product on a continuing basis and therefore
production become intermittent. Each product is a class by
itself and constitute a separate job for production process.
Shipbuilding, electric power plant dam construction etc. are
common examples of job production
CHARACTERISTICS :
The product manufacture is custom-made or non –
standardized.
Volume of output is generally small.
Variable path materials handling equipment are
used.
A wide range of general purpose machines like
grinders, drilling, press, shaper etc is used .
MERITS :
It is flexible and can be adopted easily to change in
product design. A fault in one operation does not
result into complete stoppages of the process.
it is cost effective and time- effective since the
nature of the operation in a group are similar there
is reduced materials handling since machines are
close in a cell.
The waiting period between operation is also
reduced. This also results in a work- in- progress
inventrory.
DEMERITS:
Job shop manufacturing is just most complex
system of production e. g. in building a ship
thousand of individual parts must be fabricated and
assemble.
A complex schedule of activity is required to ensure
smooth flow of work with out any bottleneck.
Raw materials and work-in-progress inventories are
high due to uneven and irregular flow of work.
Work loads are unbalanced, speed of work is slow
and unit costs are high
(B) BATCH PRODUCTION : it is defined as, “
The manufacture of a product in small or large bathes or
lots at intervals by a series of operations, each operation
being carried out on the whole batch before any subsequent
operation is performed’ the batch production is mixture of
mass production and job production and job production
under it machines turn out different product at intervals,
each product being produced for comparatively short tome
using mass production methods.
Both job production and batch production are similar in
nature, except that in batch production the quantity of
product manufacture is comparatively large.
DEMERITS :
work-in-progress inventory is high and large storage
space is required .
The main problem in batch production is ideal time
between one operation and other the work has to
wait to until a particular operation is carried out on
the whole batch.
COMPARISON OF DIFFERENT PRODUCTION
SYSTEM
As we have discussed various system and sub-system in
detail in the above lines, we can now make a comparative
study of them as follows
(1) MANUFACTURING COST : Cost of
production per unit is lowest in process production while it
is highest in job production because large scale continuous
production is carried out under process production. Unit
cost in mass production is higher while it is lower than the
batch production or job production.
(2) SIZE AND CAPITAL INVESTMENT : as stated
earlier , the scale of operation is small in job production,
medium in batch production, large in mass production
and very large in process production. Hence the size of
capital investment different from system. Process
production calls for the higher investment while mass
production requires lesser amount of capital investment .
it is lower in case of job production and comparatively
higher in batch production.
(3) FLEXIBILITY IN PRODUCTION : in case of in
demand of the product, the production facilities may be
adjust very shortly with out increasing much expenses
under the system of job or batch production .But both the
sub-system of continuous production system i.e, mass
production or process production employ single purpose
machine in their manufacturing process. They can not
adjust their production facilities so quickly and easily as
is possible in job or batch production where general
purpose machines are used
(4) REQUIRED TECHNICAL ABILITY : both job and
batch production require high skilled technical foreman and
other executives . but under mass production for process
production systems, managerial ability plays plays an
important role because it require higher ability for planning and
coordinating several functions in mass and process production
than in the case of job and batch production.
(5) ORGANISATIONAL STRUCTURE : mostly
functional organization is adopted in case of job and batch
production systems. On the other hand , divisional
organization is preferred in mass product process production
system due to the greater emphasis for centralization.
(6) JOB SECURITY : job and batch system of
production do not provide and type of job security to workers
due to their intermittent character during odd times, workers
particularly unskilled worker are thrown out of job. On the
contrary, mass and process production systems provide greater
job security to worker because production operation are carried
out continuously in anticipation of stable and continuous
demand of the product.
(7) INDUSTRIALS APPLICATION : the application
of different system is suitable in different industries depending
upon the nature of work. The mechanisum of job production
applies in products of construction and manufacturing
industries like building , bridges special purpose machines etc.
batch production is mostly used in mechanical engeering and
consumer-goods industries like cotton, jute , machine tools ,
shoe-making etc. mass production is found in automobiles,
sugar refining, refrigerators , electricals goods etc. process
production is most appropriate in chemical , petroleum , milk
processing industries etc.
Unit – II
Chapter – 1
Product Design
MAJOR FACTORS IN PRODUCT DESIGN
– Cost
– Quality
– Time-to-market
– Customer satisfaction
– Competitive advantage
PRODUCT DESIGN ACTIVITIES
• Translate customer wants and needs into
product and service requirements
• Refine existing products and services
• Develop new products and services
• Formulate quality goals
• Formulate cost targets
• Construct and test prototypes
• Document specifications
REASONS FOR PRODUCT DESIGN
• Economic
• Social and demographic
• Political, liability, or legal
• Competitive
• Technological
OBJECTIVES OF PRODUCT DESIGN
Main focus
– Customer satisfaction
Secondary focus
– Function of product/service
– Cost/profit
– Quality
– Appearance
– Ease of production/assembly
– Ease of maintenance/service
FORMS OF PRODUCT DESIGN
1. Priliminary Design – Pre design or proto type of the
product design
2. Final Design – Final decision making of the product design
after testing etc.,
3.Modular Design - is a form of standardization in which
component parts are subdivided into modules that are easily
replaced or interchanged. It allows:
– easier diagnosis and remedy of failures
– easier repair and replacement
– simplification of manufacturing and assembly
4. Reverse Engineering - Reverse engineering is the
dismantling and inspecting of a competitor’s product to
discover product improvements.
PHASES IN PRODUCT DEVELOPMENT PROCESS
1. Idea generation
2. Feasibility analysis
3. Product specifications
4. Process specifications
5. Prototype development
6. Design review
7. Market test
8. Product introduction
9. Follow-up evaluation
UNIT – II
Chapter – 2
Make-or-Buy Decisions
The make-or-buy decision is the act of making a
strategic choice between producing an item internally (in-
house) or buying it externally (from an outside supplier). The
buy side of the decision also is referred to as outsourcing.
Make-or-buy decisions usually arise when a firm that has
developed a product or part—or significantly modified a
product or part—is having trouble with current suppliers, or
has diminishing capacity or changing demand.
Make-or-buy analysis is conducted at the strategic and
operational level. Obviously, the strategic level is the more
long-range of the two. Variables considered at the strategic
level include analysis of the future, as well as the current
environment. Issues like government regulation, competing
firms, and market trends all have a strategic impact on the
make-or-buy decision.
FACTORS CONSIDERATIONS THAT FAVOR
MAKING A PART IN-HOUSE:
Cost considerations (less expensive to make the part)
Desire to integrate plant operations
Productive use of excess plant capacity to help absorb
fixed overhead (using existing idle capacity)
Need to exert direct control over production and/or
quality
Better quality control
Design secrecy is required to protect proprietary
technology
Unreliable suppliers
No competent suppliers
Desire to maintain a stable workforce (in periods of
declining sales)
Quantity too small to interest a supplier
Control of lead time, transportation, and warehousing
costs
Greater assurance of continual supply
Provision of a second source
Political, social or environmental reasons (union
pressure)
Emotion (e.g., pride)
FACTORS THAT MAY INFLUENCE FIRMS TO BUY A
PART EXTERNALLY INCLUDE:
Lack of expertise
Suppliers' research and specialized know-how exceeds
that of the buyer
cost considerations (less expensive to buy the item)
Small-volume requirements
Limited production facilities or insufficient capacity
Desire to maintain a multiple-source policy
Indirect managerial control considerations
Procurement and inventory considerations
Brand preference
Item not essential to the firm's strategy
Cost considerations for the "Make " analysis include:
Incremental inventory-carrying costs
Direct labor costs
Incremental factory overhead costs
Delivered purchased material costs
Incremental managerial costs
Any follow-on costs stemming from quality and related
problems
Incremental purchasing costs
Incremental capital costs
Cost considerations for the "buy" analysis include:
Purchase price of the part
Transportation costs
Receiving and inspection costs
Incremental purchasing costs
Any follow-on costs related to quality or service
Unit - II
Chapter – 3
Modern Production Management
( CIM, CAD, CAM, FMS)
Computer Integrated Manufacturing
Computer-Integrated Manufacturing (CIM) in
engineering is a method of manufacturing in which the entire
production process is controlled by computer. Typically, it
relies on closed-loop control processes, based on real-time
input from sensors. It is also known as flexible design and
manufacturing.
Overview
The term "Computer Integrated Manufacturing" is both
a method of manufacturing and the name of a computer-
automated system in which individual engineering, production,
marketing, and support functions of a manufacturing enterprise
are organized. In a CIM system functional areas such as design,
analysis, planning, purchasing, cost accounting, inventory
control, and distribution are linked through the computer with
factory floor functions such as materials handling and
management, providing direct control and monitoring of all
process operations.
As method of manufacturing, three components distinguish
CIM from other manufacturing methodologies:
Means for data storage, retrieval, manipulation and
presentation;
Mechanisms for sensing state and modifying processes;
Algorithms for uniting the data processing component
with the sensor/modification component.
CIM is basically use of Information and Communication
Technology (ICT)in manufacturing.
History of CIM
The idea of "Digital Manufacturing" is a vision for the
1980s. In the 1980s, Computer Integrated Manufacturing was
developed and promoted by machine tool manufacturers and
the CASA/SME (Computer and Automated Systems
Association /Society for Manufacturing Engineers).
"CIM is the integration of total manufacturing
enterprise by using integrated systems and data
communication coupled with new managerial
philosophies that improve organizational and personnel
efficiency."
Key Challenges to CIM
There are three major challenges to development of a smoothly
operating Computer Integrated Manufacturing system:
Integration of components from different suppliers:
When different machines, such as CNC, conveyors and
robots, are using different communications protocols. In
the case of AGVs, even differing lengths of time for
charging the batteries may cause problems.
Data integrity : The higher the degree of automation, the
more critical is the integrity of the data used to control
the machines. While the CIM system saves on labor of
operating the machines, it requires extra human labor in
ensuring that there are proper safeguards for the data
signals that are used to control the machines.
Process control : Computers may be used to assist the
human operators of the manufacturing facility, but there
must always be a competent engineer on hand to handle
circumstances which could not be foreseen by the
designers of the control software.
Subsystems in Computer Integrated Manufacturing
A Computer Integrated Manufacturing system is not the same
as a "lights out" factory, which would run completely
independent of human intervention, although it is a big step in
that direction. Part of the system involves flexible
manufacturing, where the factory can be quickly modified to
produce different products, or where the volume of products
can be changed quickly with the aid of computers. Some or all
of the following subsystems may be found in a CIM operation:
CAD/CAM (Computer-aided design/Computer-aided
manufacturing)
CAPP, (Computer-aided process planning)
ERP (Enterprise resource planning)
CNC (computer numerical control) machine tools
DNC, direct numerical control machine tools
FMS, flexible machining systems
ASRS, automated storage and retrieval systems
AGV, automated guided vehicles
Robotics
Automated conveyance systems
Computerized scheduling and production control
CAQ (Computer-aided quality assurance)
A business system integrated by a common database.
Lean Manufacturing
Computer-aided design
Computer-Aided Design (CAD) is the use of computer
technology to aid in the design and particularly the drafting
(technical drawing and engineering drawing) of a part or
product, including entire buildings. It is both a visual (or
drawing) and symbol-based method of communication whose
conventions are particular to a specific technical field.
Drafting can be done in two dimensions ("2D") and three
dimensions ("3D").
Drafting is the communication of technical or
engineering drawings and is the industrial arts sub-discipline
that underlies all involved technical endeavors. In representing
complex, three-dimensional objects in two-dimensional
drawings, these objects have traditionally been represented by
three projected views at right angles.
Overview
Current Computer-Aided Design software packages
range from 2D vector-based drafting systems to 3D solid and
surface modellers. Modern CAD packages can also frequently
allow rotations in three dimensions, allowing viewing of a
designed object from any desired angle, even from the inside
looking out. Some CAD software is capable of dynamic
mathematic modeling, in which case it may be marketed as
CADD — computer-aided design and drafting.
CAD is used in the design of tools and machinery and
in the drafting and design of all types of buildings, from small
residential types (houses) to the largest commercial and
industrial structures (hospitals and factories).
CAD is mainly used for detailed engineering of 3D
models and/or 2D drawings of physical components, but it is
also used throughout the engineering process from conceptual
design and layout of products, through strength and dynamic
analysis of assemblies to definition of manufacturing methods
of components.
CAD has become an especially important technology
within the scope of computer-aided technologies, with benefits
such as lower product development costs and a greatly
shortened design cycle. CAD enables designers to lay out and
develop work on screen, print it out and save it for future
editing, saving time on their drawings.
Uses
Computer-Aided Design is one of the many tools used
by engineers and designers and is used in many ways
depending on the profession of the user and the type of
software in question. There are several different types of CAD.
Each of these different types of CAD systems require the
operator to think differently about how he or she will use them
and he or she must design their virtual components in a
different manner for each.
There are many producers of the lower-end 2D systems,
including a number of free and open source programs. These
provide an approach to the drawing process without all the fuss
over scale and placement on the drawing sheet that
accompanied hand drafting, since these can be adjusted as
required during the creation of the final draft.
3D wireframe is basically an extension of 2D drafting. Each
line has to be manually inserted into the drawing. The final
product has no mass properties associated with it and cannot
have features directly added to it, such as holes. The operator
approaches these in a similar fashion to the 2D systems,
although many 3D systems allow using the wireframe model to
make the final engineering drawing views.
The Effects of CAD
Starting in the late 1980s, the development of readily
affordable Computer-Aided Design programs that could be run
on personal computers began a trend of massive downsizing in
drafting departments in many small to mid-size companies. As
a general rule, one CAD operator could readily replace at least
three to five drafters using traditional methods. Additionally,
many engineers began to do their own drafting work, further
eliminating the need for traditional drafting departments. This
trend mirrored that of the elimination of many office jobs
traditionally performed by a secretary as word processors,
spreadsheets, databases, etc. became standard software
packages that "everyone" was expected to learn.
Another consequence had been that since the latest
advances were often quite expensive, small and even mid-size
firms often could not compete against large firms who could
use their computational edge for competitive purposes. Today,
however, hardware and software costs have come down. Even
high-end packages work on less expensive platforms and some
even support multiple platforms. The costs associated with
CAD implementation now are more heavily weighted to the
costs of training in the use of these high level tools, the cost of
integrating a CAD/CAM/CAE PLM using enterprise across
multi-CAD and multi-platform environments and the costs of
modifying design work flows to exploit the full advantage of
CAD tools.
CAD vendors have effectively lowered these training costs.
These methods can be split into three categories:
1. Improved and simplified user interfaces. This includes
the availability of “role” specific tailor able user
interfaces through which commands are presented to
users in a form appropriate to their function and
expertise.
2. Enhancements to application software. One such
example is improved design-in-context, through the
ability to model/edit a design component from within
the context of a large, even multi-CAD, active digital
mockup.
3. User oriented modeling options. This includes the
ability to free the user from the need to understand the
design intent history of a complex intelligent model.
Computer - Aided Manufacturing
(CAM)
Definition:
Computer-Aided Manufacturing (CAM) is the use of computer
software and hardware in the translation of computer-aided
design models into manufacturing instructions for numerical
controlled machine tools.
Applications
The field of computer-aided design has steadily advanced
over the past four decades to the stage at which conceptual
designs for new products can be made entirely within the
framework of CAD software. From the development of the
basic design to the Bill of Materials necessary to manufacture
the product there is no requirement at any stage of the process
to build physical prototypes.
Computer-Aided Manufacturing takes this one step further by
bridging the gap between the conceptual design and the
manufacturing of the finished product. Whereas in the past it
would be necessary for a design developed using CAD
software to be manually converted into a drafted paper drawing
detailing instructions for its manufacture, Computer-Aided
Manufacturing software allows data from CAD software to be
converted directly into a set of manufacturing instructions.
CAM software converts 3D models generated in CAD into a
set of basic operating instructions written in G-Code. G-code is
a programming language that can be understood by numerical
controlled machine tools – essentially industrial robots – and
the G-code can instruct the machine tool to manufacture a large
number of items with perfect precision and faith to the CAD
design.
Modern numerical controlled machine tools can be linked into
a ‘cell’, a collection of tools that each performs a specified task
in the manufacture of a product. The product is passed along
the cell in the manner of a production line, with each machine
tool (i.e. welding and milling machines, drills, lathes etc.)
performing a single step of the process.
In addition to lower running costs there are several additional
benefits to using CAM software. By removing the need to
translate CAD models into manufacturing instructions through
paper drafts it enables manufactures to make quick alterations
to the product design, feeding updated instructions to the
machine tools and seeing instant results.
In addition, many CAM software packages have the ability to
manage simple tasks such as the re-ordering of parts, further
minimising human involvement. Though all numerical
controlled machine tools have the ability to sense errors and
automatically shut down, many can actually send a message to
their human operators via mobile phones or e-mail, informing
them of the problem and awaiting further instructions.
All in all, CAM software represents a continuation of the trend
to make manufacturing entirely automated. While CAD
removed the need to retain a team of drafters to design new
products, CAM removes the need for skilled and unskilled
factory workers. All of these developments result in lower
operational costs, lower end product prices and increased
profits for manufacturers.
Problems
Unfortunately, there are several limitations of computer-aided
manufacturing. Obviously, setting up the infrastructure to
begin with can be extremely expensive. Computer-aided
manufacturing requires not only the numerical controlled
machine tools themselves but also an extensive suite of
CAD/CAM software and hardware to develop the design
models and convert them into manufacturing instructions – as
well as trained operatives to run them.
Additionally, the field of computer-aided management is
fraught with inconsistency. While all numerical controlled
machine tools operate using G-code, there is no universally
used standard for the code itself. Since there is such a wide
variety of machine tools that use the code it tends to be the case
that manufacturers create their own bespoke codes to operate
their machinery.
While this lack of standardisation may not be a problem in
itself, it can become a problem when the time comes to convert
3D CAD designs into G-code. CAD systems tend to store data
in their own proprietary format (in the same way that word
processor applications do), so it can often be a challenge to
transfer data from CAD to CAM software and then into
whatever form of G-code the manufacturer employs.
FLEXIBLE MANUFACTURING SYSTEM
A flexible manufacturing system (FMS) is a
manufacturing system in which there is some amount of
flexibility that allows the system to react in the case of
changes, whether predicted or unpredicted. This flexibility is
generally considered to fall into two categories, which both
contain numerous subcategories.
1. The first category, machine flexibility, covers the system's
ability to be changed to produce new product types, and ability
to change the order of operations executed on a part.
2. The second category is called routing flexibility, which
consists of the ability to use multiple machines to perform the
same operation on a part, as well as the system's ability to
absorb large-scale changes, such as in volume, capacity, or
capability.
Most FMS systems comprise of three main systems. The work
machines which are often automated CNC machines are
connected by a material handling system to optimize parts flow
and the central control computer which controls material
movements and machine flow.
The main advantages of an FMS is its high flexibility in
managing manufacturing resources like time and effort in order
to manufacture a new product. The best application of an FMS
is found in the production of small sets of products like those
from a mass production.
Advantages
Productivity increment due to automation
Preparation time for new products is shorter due to
flexibility
Saved labor cost, due to automation
Improved production quality, due to automation
However, it is not always necessary that on increasing
flexibility productivity also increases.
Industrial FMS Communication
An Industrial Flexible Manufacturing System (FMS)
consists of robots, Computer-controlled Machines, Numerical
controlled machines (CNC), instrumentation devices,
computers, sensors, and other stand alone systems such as
inspection machines. The use of robots in the production
segment of manufacturing industries promises a variety of
benefits ranging from high utilization to high volume of
productivity. Each Robotic cell or node will be located along a
material handling system such as a conveyor or automatic
guided vehicle. The production of each part or work-piece will
require a different combination of manufacturing nodes. The
movement of parts from one node to another is done through
the material handling system. At the end of part processing, the
finished parts will be routed to an automatic inspection node,
and subsequently unloaded from the Flexible Manufacturing
System.
The FMS data traffic consists of large files and short
messages, and mostly come from nodes, devices and
instruments. The message size ranges between a few bytes to
several hundreds of bytes. Executive software and other data,
for example, are files with a large size, while messages for
machining data, instrument to instrument communications,
status monitoring, and data reporting are transmitted in small
size.
There is also some variation on response time. Large
program files from a main computer usually take about 60
seconds to be down loaded into each instrument or node at the
beginning of FMS operation. Messages for instrument data
need to be sent in a periodic time with deterministic time delay.
Other type of messages used for emergency reporting is quite
short in size and must be transmitted and received with almost
instantaneous response.
The demands for reliable FMS protocol that support all
the FMS data characteristics are now urgent. The existing IEEE
standard protocols do not fully satisfy the real time
communication requirements in this environment. The delay of
CSMA/CD is unbounded as the number of nodes increases due
to the message collisions. Token Bus has a deterministic
message delay, but it does not support prioritized access
scheme which is needed in FMS communications. Token Ring
provides prioritized access and has a low message delay,
however, its data transmission is unreliable. A single node
failure which may occur quite often in FMS causes
transmission errors of passing message in that node. In
addition, the topology of Token Ring results in high wiring
installation and cost.
A design of FMS communication protocol that supports a real
time communication with bounded message delay and reacts
promptly to any emergency signal is needed. Because of
machine failure and malfunction due to heat, dust, and
electromagnetic interference is common, a prioritized
mechanism and immediate transmission of emergency
messages are needed so that a suitable recovery procedure can
be applied. A modification of standard Token Bus to
implement a prioritized access scheme was proposed to allow
transmission of short and periodic messages with a low delay
compared to the one for long messages.
Unit – II
Chapter – 4
DEMAND FORECASTING
Forecasts are needed to aid in determining what
resources are needed, scheduling existing resources, and
acquiring additional resources. Accurate forecasts allow
scheduler to use machine capacity efficiently, reduce
production times, and cut inventories.
Forecasting methods may be based on mathematical models
using historical data available, qualitative methods drawing on
managerial experience, or a combination of both.
Forecasting demand in such situations require uncovering the
underlying patterns from available information.
PATTERNS OF DEMAND
The five basic patterns of the most demand time series are-:
1. Horizontal, or the fluctuation of data around a constant
mean;
2. Trend, or systematic increase or decrease in the mean of
the series overtime;
3. Seasonal, or a repeatable pattern of increase or decrease
in demand, depending on the time of day, week, month,
or season;
4. Cyclic, or less predictable gradual increases or
decreases in demand over longer periods of time (years
or decades); and
5. Random, or unforecastable, variation in demand
Four of the patterns of demands- Horizontal, Trend, Seasonal,
and Cyclic- combine in varying degrees to define the
underlying time pattern of demand for a product or service.
The fifth pattern, random variations, results from chance causes
and thus cannot be predicted.
FACTORS AFFECTING DEMAND
Generally such factors can be divided into main categories: -
Externals and Internals.
I. External Factors. External factors that affect demand for a
firm’s products or services are beyond management’s control.
Leading indicators. Such as the rate of business failures,
are external factors with turning points that typically precede
the peaks and troughs of general business cycle. Coincident
indicator, such as unemployment figures, are the time series
with turning points that generally match those of the general
business cycle.
Lagging indicators, such as retail sales, follow those turning
points, typically by several weeks or months.
II. Internal Factors: internal decision about product or service
design, price and advertising promotion, packaging design,
sales persons quotas or incentive and expansion and
contraction of geographic market, target areas all contribute to
changes in demand volume. The term demand management
describes the process of influencing the timing and volume of
demand or adapting to the undesirable effects of unchangeable
demand patterns.
Forecasting methods The two general types of forecasting
techniques used for demand forecasting are: Qualitative
methods and Quantitative methods
II.QUALITATIVE METHODS
a) Sales Force Estimate
Sales force estimates are forecasts compiled from estimates of
future demand made periodically by members of a company’s
sales force. This approach has several advantages.
The sales force is the group most likely to know which
products or services customers will be buying in the
near future, and in what quantities.
Sales territories often are divided by district or region.
Information broken down in this manner can be useful
for inventory management, distribution, and sales force
staffing purposes.
The forecasts of individual sales force members can be
combined easily to get regional or national sales.
But it also has several disadvantages.
Individual biases of the sales people may taint the
forecast; moreover, some people are naturally
optimistic, other more cautious.
Sales people may not always be able to detect the
difference between what a customers “wants” (a wish
list) and what a customer “needs” (a necessary
purchase).
If the firm uses individual sales as a performance
measure, salespeople may underestimate their forecasts
so that their performance will look good when they
exceed their projections or may work hard only until
they reach their required minimum sales.
b) Executive opinion
Executive opinion is a forecasting method in which the
opinions, and technical knowledge of one or more managers
are summarized to arrive at a single forecast. As we will
discuss later, executive opinion can be used to modify an
existing sales forecast to account for unusual circumstances,
such as a new sales promotion or unexpected international
events. Executive opinion can also be used for technical
forecasting. This method of forecasting has several
disadvantages. Executive opinion can be costly because it takes
valuable executive time. Although that may be warranted under
certain circumstances, it sometimes gets out of control. In
addition, if executives are allowed to modify a forecast without
collectively agreeing to the changes, the resulting forecast will
not be useful.
c) Market research
Market research is a systematic approach to
determine consumer interest in a product or services by
creating and testing hypotheses through data-gathering surveys.
Conducting a market research study includes
1. Designing a questionnaire that request economic and
demographics information from each person
interviewed and asks whether the interviewee would be
interested in the product or services;
2. Deciding how an administrative sample of household to
survey, whether by telephone polling, mailings, or
personal interviews;
3. Selecting a representative sample of households to
survey, which should include a random selection within
the market area of the proposed product or service; and
4. Analyzing the information using judgment and
statistical tools to interpret the responses, determine
their adequacy, make allowance for economic or
competitive factors not included in the questionnaire,
and analyze whether the survey represents a random
sample of the potential market.
Market research may be used to forecast demand for the short,
medium, and long term. Accuracy is excellent for the short
term, good for the medium term, and only fair for the long
term.
d) Delphi method
The Delphi method is process of gaining consensus
from a group of experts while maintaining their anonymity.
This form of forecasting is useful when there are no historical
data from which to develop statistical models and when
managers inside the firm have no experience on which to base
informed projections. A coordinator sends a question to each
member of the group of outside experts, who may not even
know who else, is participating. The Delphi method can be
used to develop long-range forecasts of product demand and
new product sales projections. It can also be used for
technological forecasting. The Delphi methods can be used to
obtain a consensus from a panel of experts who can devote
their attention to following scientific advances, changes in
society, government regulations, and the competitive
environment.
The Delphi method has some shortcomings, including the
following major ones.
The process can take a long time (sometime a year or
more). During that time the panel of people considered
to be experts may change, confounding the results or at
least further lengthening the process.
Responses may be less meaningful than if experts were
accountable for their responses.
There is little evidence that Delphi forecasts achieve
high degrees of accuracy. However, they are known to
be fair- to- good in identifying turning points in new
product demand.
Poorly designed questionnaires will result in ambiguous
or false conclusions.
II. QUANTITATIVE METHOD
a) Linear Regression
In linear regression, one variable, called a dependent variable,
is related to one or more independent variables by a linear
equation.
In the simple linear regression models, the dependent variable
is a function of only one independent variable, and therefore
the theoretical relationship is a straight line:
Y=a + bX
Where Y = dependent variable
X = independent variable
a = Y-intercept of the line
b = slope of the line.
The objectives of linear regression analysis is to find values of
a and b that minimize the sum of squared deviations of the
actual data points from the graphed line.
The sample correlation coefficient, r, measures the direction
and strength of the relationship between the independent
variable and the dependent variable. The value of r can range
from – 1.00 to + 1.00.
b) Time series methods
Simple Moving Averages. The simple moving
average method is used to estimate the average of demand time
series and thereby remove the effects of random fluctuation. It
is most useful when demand has no pronounced trend or
seasonal influences.
Weighted Moving Averages. In the simple moving
average method, each demand has the same weight in the
average --namely, 1/n. In the weighted moving average
method; each historical demand in the average can have its
own weight. The sum of the weight equal 1.0.
The advantage of a weighted moving average method is that it
allows you to emphasize recent demand over earlier demand.
The forecast will be more responsive than the simple moving
average forecast to changes in the underlying average of the
demand series. Nonetheless, the weighted moving average
forecast will still lag behind demand because it merely
averages past demands. This lag is specially noticeable with a
trend because the average of the time series is systematically
increasing or decreasing.
c) Exponential smoothing.
The exponential smoothing method is a sophisticated weighted
moving average method that calculates the average of a time
series by giving recent demands more weight than earlier
demands. It is the most frequently used formal forecasting
methods because of its simplicity and the small amount of data
needed to support it.
Ft+1 =a(Demand this period) + (1-a) (Forecast calculated last
period)= aDt+(1-a)Ft
Ft+1 =Ft + a(Dt-Ft)
Larger a values emphasize recent levels of demand and result
in forecasts more responsive to changes in the underlying
average. Smaller a values treat past demand more uniformly
and result in more stable forecasts.
Exponential smoothing requires an initial forecast to get
started. There are two ways to get this initial forecast: Either
use last period’s demand or, if some historical data are
available, calculate the average of several recent periods of
demand. The effect of the initial estimate of the average on
successive estimate of the average diminishes over time
because, with exponential smoothing, the weights given to
successive historical demands used to calculate the average
decay exponentially.
Exponential smoothing has the advantages of simplicity and
minimal data requirements. It is inexpensive to use and
therefore very attractive to firms that make thousands of
forecasts for each time period. However, its simplicity also is
disadvantage when the underlying average is changing, as in
the case of a demand series with a trend.
Unit – III
Chapter – 1
Production Planning & Control
Production Planning and control are basic managerial
functions which are essential to every organized activity. Proper
planning and control of manufacturing activities or the
production system is equally essential for efficient and
economical production. Economy and productivity are to a large
extent directly proportional to the thoroughness with which the
planning and control functions are performed. In a modern
enterprise, production is a complex system and steps must be
taken to ensure that goods are produced in the right quantity and
quality, at the right time and place and by the most efficient
methods possible. This is the task of production planning and
control.
PRODUCTION PLANNING
Production planning is concerned with deciding in
advance what is to be produced, when to be produced, where to
be produced and how to be produced. It involves foreseeing
every step in the process of production so as to avoid all
difficulties and inefficiency in the operation of the plant.
Production planning has been defined as the technique of
forecasting or picturing ahead every step in a long series of
separate operations, each step to be taken in the right place, of
the right degree, and at the right time, and each operation to be
done at maximum efficiency. In other words, production
planning involves looking ahead, anticipating bottlenecks and
identifying the steps necessary to ensure smooth and
uninterrupted flow of production. It determines the requirements
for materials, machinery and man-power; establishes the exact
sequence of operations for each individual item and lays down
the time schedule for its completion.
Objectives of Production Planning
The basic objectives of production planning are as under:-
(i) On the basis of the sales forecast and its engineering
analysis, to estimate the kind of the resources like
men, materials, machines, methods etc. in proper
quantities and qualities. It also estimates when and
where these resources will be required so that the
production of the desired goods is done most
economically.
(ii) It also aims to make all necessary arrangement so that
the production targets as set in the production budget
and master schedules are reached. While attaining
these targets, adjustments are made for the
fluctuations in the demand.
For an effective planning of production activities, the
executives concerned must have complete information
regarding the following:-
(i) Engineering data including complete analysis of
the product to be manufactured ,the operations,
processes and methods through which each
component or class of product must pass, the
nature of inspection required, and the method of
assembly.
(ii) Machine analysis giving full information
regarding speeds of all available machines and
their maximum capacity to perform certain
operations, and the rate of output per day, week
or month, and the maximum plant capacity per
day for each process or operation.
(iii) The various types and classes of tools and
equipment required of production.
(iv) Material analysis giving full information as to the
type, quality and quantity of the raw material to
be used in each process or operation. Also,
information as to raw materials in stores, how
much are on order, and how much are a located or
reserved for current orders.
(v) The characteristics of each job and the degree of
skill and personnel qualifications required for the
effective performance of each such job.
(vi) Information relating to power production and
consumption, internal transport and material
handling service.
(vii) Job analysis giving information as to what
methods of operation would yield uniformity of
output, ease in production and reduction in costs.
(viii) Information as to the customers orders on hand,
and the delivery for customers, and what for stock
purpose.
It is the job of the production department to arrange for the
order in which the work will be done the routing and
scheduling of work, and determine what machines tools,
workplaces materials and operatives should do the work.
A balanced production planning would tend to increase
operating efficiency by stabilizing productive activities,
facilitate selling and customer service, and help reduce
production cost by providing reliable basis for investment in
raw materials and tools. It would promote fuller utilization of
plant, equipment and labour by controlling all time and
efforts essential in manufacturing.
Levels of Production Planning
Production planning can be done at three levels namely
Factory Planning, Process Planning and Operation Planning
which are as follows:
(i) Factory Planning: At this level of planning the
sequence of work/ tasks is planned in terms of
building machines and equipment required for
manufacturing the desired goods and services. The
relationship of workplaces in terms of departments is
also planned at this stage taking into consideration the
space available for the purpose.
(ii) Process Planning: There are many operations
involved in factory planning for transforming the
inputs into some desired end product. In process
planning these operations are located and the
sequence of these operations in the production
process is determined. Plans are also made for the
layout of work centers in each process.
(iii) Operation Planning: It is concerned with planning
the details of the methods required to perform each
operation viz. selection of work centers, designing of
tools required for various operations. Then the
sequences of work elements involved in each
operation are planned. Specifications about each
transfer, work centers, nature of tools required and the
time necessary for the completion of each operation
are prescribed.
PRODUCTION CONTROL
All organizations irrespective of size, use production
control to some degree. In small organizations, the production
control may be performed by one person; but in large complex
industries the production control department is normally well-
organised and highly specialized. Production control
presupposes the existence of production plans, and it involves the
use of various control techniques to ensure production
performance as per plans. Co-ordinating men and materials and
machines is the task of production control.
Production control may be defined as “the process of planning
production in advance of operations; establishing the exact route
of each individual item, part of assembly; setting and finishing
dates for each important item, assembly and the finished
products, and releasing the necessary orders as well as initiating
the required follow-up to effectivate the smooth functioning of
the enterprises.” According to Henry Fayol, production control
is the art and science of ensuring that all which occurs is in
accordance with the rules established and the instructions
issued”. Thus, production control regulates the orderly flow of
materials in the manufacturing process from the raw material
stage to the finished product.
Production control aims at achieving production targets,
optimum use of available resources, increased profits through
productivity, better and more economic goods and services etc.
An effective production control system requires reliable
information, sound organization structure, a high degree of
standardization and trained personnel for its successful operation.
A sound production control system contributes to the efficient
operation of plant. In terms of manufacturing customer’s orders,
production control assures a more positive and accurate
completion and delivery date. Delivering an order on time is
obviously important to the customer and to the development of
customer goodwill. Production control also brings plan and
order to chaotic and haphazard manufacturing procedures. This
not only increases the plant efficiency but also makes it a more
pleasant place in which to work. Most people recognize that
employees prefer to work and do better work under conditions of
obvious control and plan. Morale may be considerably
improved.. Effective production control also maintains working
inventories at a minimum, making possible a real saving in both
labour and material investment. Thus, good production control
helps a company operate and produce more efficiently and
achieve lowest possible costs.
Objectives of Production Control
The success of an enterprise greatly depends on the performance
of its production control department. The production control
department generally has to perform the following functions:
(i) Provision of raw material, equipment, machines and
labour.
(ii) To organize production schedule in conformity with
the demand forecasts.
(iii) The resources are used in the best possible manner in
such a way that the cost of production is minimized
and delivery date is maintained.
(iv) Determination of economic production runs with a
view to reduce setup costs.
(v) Proper co-ordination of the operations of various
sections/departments responsible for production.
(vi) To ensure regular and timely supply of raw material
at the desired place and of prescribed quality and
quantity to avoid delays in production.
(vii) To perform inspection of semi-finished and finished
goods and use quality control techniques to ascertain
that the produced items are of required specifications.
(viii) It is also responsible for product design and
development.
Thus the fundamental objective of production control is to
regulate and control the various operations of production
process such a way that orderly flow of material is ensured at
different stages of the production and the items are produced
of right quality, in right quantity, at the right time with
minimum efforts and cost.
Levels of Production Control
Production control starts with some particular goal and
formulation of some general strategy for the accomplishment of
desired objectives. There are three levels of production control
namely programming, ordering and dispatching. Programming
plans the output of products for the factory as a whole. Ordering
plans the output of components from the suppliers and
processing departments. Dispatching considers each processing
department in turn and plans the output from the machine, tools
and other work centers so as to complete the orders by due date.
Factors Determining Production Control
The nature of production control operations varies from
organization to organization. The following factors affect the
nature and magnitude of production control methods in an
organization.
a) Nature of production: In job-oriented manufacturing,
products and operations are designed for some particular order
which may or may not be repeated in future. Hence
production usually requires more time, whereas in a continuous
manufacturing system inventory problems are more complex
but control operations are rather simple due to fixed process.
In mixed stock and custom manufacturing systems the problem
of control is further complicated due to simultaneous
scheduling of combined process.
b) Nature of operations/activities: In intermittent
manufacturing system the operations are markedly varied in
terms of their nature, sequence and duration. Due to this the
control procedure requires continuous modifications and
adjustments to suit the requirements of each order.
c) Magnitude of operations: Centralised control secures the
most effective co-ordination but as an organization grows in
size, decentralization of some production control functions
becomes necessary. The degree to which the performance of
an activity should be decentralized depends upon the scope of
operations and convenience of their locations.
PRODUCTION PLANNING AND CONTROL
Planning and control are interrelated and
interdependent. Planning is meaningless unless control action
is taken to ensure the success of the plan. Control also
provides information feedback which is helpful in modifying
the existing plans and in making new plans. Similarly, control
is dependent on planning as the standards of performance are
laid down under planning. Therefore, production and control
should be considered an integrated function of planning to
ensure the most efficient production and regulation of
operations to execute the plans successfully.
Production planning and control may be defined as the
direction and coordination of the firm’s material and physical
facilities towards the attainment of pre-specified production
goals in the most efficient available way .It is the process of
planning production in advance of operations, establishing the
exact route of each individual item, part or assembly, setting
starting and finishing dates for each important item or
assembly and finished products, and releasing the necessary
orders as well as initiating the required follow up to effectuate
the smooth functioning of the enterprise. Thus, production
planning and control involves planning, routing, scheduling,
dispatching and expediting to coordinate the movements of
materials, machines and manpower as to quantity, quality, time
and place. It is based upon the old adage of “first plan your
work and then work your plan”.
Objectives of Production Planning and Control
The main objective of production planning and control is to
ensure the coordinated flow of work so that the required
number of products are manufactured in the required quantity
and of required quality at the required time at optimum
efficiency. In other words, production planning and control
aims at the following purposes:
a) Continuous Flow of Production: It tries to achieve
as smooth and continuous production by eliminating
successfully all sorts of bottlenecks in the process of
production through well-planned routing and
scheduling requirements relating to production
work.
b) Planned Requirements of Resources: It seeks to
ensure the availability of all the inputs i.e. materials,
machines, tools, equipment and manpower in the
required quantity, of the required quality and at the
required time so that desired targets of production
may be achieved.
c) Co-ordinated work Schedules: The production
activities planned and carried out in a
manufacturing organization as per the master
schedule. The production planning and control tries
to ensure that the schedules to be issued to the
various departments/units/supervisors are in co-
ordination with the master schedule.
d) Optimum Inventory: It aims at minimum
investment in inventories consistent with
continuous flow of production.
e) Increased Productivity: It aims at increased
productivity by increasing efficiency and by being
economical. This is achieved by optimizing the use
of productive resources and eliminating wastage
and spoilage.
f) Customer Satisfaction : It also aims at satisfying
customers’ requirements by producing the items as
per the specifications or desires of the customers. It
seeks to ensure delivery of products on time by co-
ordinating the production operations with
customers’ orders.
g) Production and Employment Stabilisation:
Production planning and control aims at ensuring
production and employment levels that are
relatively stable and consistent with the quantity of
sales.
h) Evaluation of Performance: The process of
production planning and control is expected to keep
a constant check on operations by judging the
performance of various individuals and workshops
and taking suitable corrective measures if there is
any deviation between planned and actual
operations.
Importance of Production Planning and Control
The system of production planning and control serves
as the nervous system of a plant. It is a co- ordinating agency
which co-ordinate the activities of engineering, purchasing,
production, selling and stock control departments. An efficient
system of production planning and control helps in providing
better and more economic goods to customers at lower
investment. It is essential in all plants irrespective of their
nature and size. The principal advantages of production
planning and control are summarized below:
(i) Better Service to Customers: Production planning and
control, through proper scheduling and expediting of work,
helps in providing better services to customers is terms of
better quality of goods at reasonable prices as per promised
delivery dates. Delivery in time and proper quality, both help in
winning the confidence of customers, improving relations with
customers and promoting profitable repeat orders.
(ii) Fewer Rush Orders :In an organization, where there is
effective system of production planning and control,
production, operations move smoothly as per original planning
and matching with the promised delivery dates. Consequently,
there will be fewer rush orders in the plant and less overtime
than, in the same industry, without adequate production
planning and control.
(iii) Better Control of Inventory: A sound system of
production planning and control helps in maintaining inventory
at proper levels and, thereby, minimizing investment in
inventory. It requires lower inventory of work-in-progress and
less finished stock to give efficient service to customers. It
also helps in exercising better control over raw-material
inventory, which contributes to more effective purchasing.
(iv) More Effective Use of Equipment : An efficient
system of production planning and control makes for the most
effective use of equipment. It provides information to the
management on regular basis pertaining to the present position
of all orders in process, equipment and personnel requirements
for next few weeks. The workers can be communicated well in
advance if any retrenchment, lay-offs, transfer, etc. is likely to
come about. Also, unnecessary purchases of equipment and
materials can be avoided. Thus, it is possible to ensure proper
utilization of equipment and other resources.
(v) Reduced Idle Time: Production planning and control
helps in reducing idle time i.e. loss of time by workers waiting
for materials and other facilities; because ensures that material
and other facilities are available to the workers in time as per
the production schedule. Consequently, less man-hours are
lost, which has a positive impact on the cost of production.
(vi) Improved Plant Morale: An effective system of
production planning and control co-ordinates the activities of
all the departments involved in the production activity. It
ensures even flow of work and avoids rush orders. It maintains
healthy working conditions in the plant thus, there is improve
plant morale as a by-product.
(vii) Good public image: A proper system of production
planning and control is helpful in keeping systematized
operations in an organization .Such an organization is in a
position to meet its orders in time to the satisfaction of its
customers. Customers satisfaction leads to increased sales,
increased profits ,industrial harmony and, ultimately, good
public image of the enterprise .
(viii) Lower capital requirements: Under a sound system
of production planning and control , everything relating to
production is planned well in advance of operations.
Where, when and what is required in the form of input is known
before the actual production process starts .Inputs are made
available as per schedule which ensures even flow of production
without any bottlenecks .Facilities are used more effectively and
inventory levels are kept as per schedule neither more nor
less .Thus ,production planning and control helps, in minimizing
capital investment in equipment and inventories.
Basic Elements of PPC ( Refer Class notes also)
1. Routing
Routing may be defined as the selection of path, which each
part of the product will follow, which being transformed from
raw material to finished products. Routing determines the most
advantageous path to be followed for department to department
and machine to machine till raw material gets its final shape.
Factors Affecting Routing Procedure:
Manufacturing type
Availability of plant equipment and its component
parts.
Human factors.
2. Scheduling
Scheduling determines the programme for the operations.
Scheduling may be defined as 'the fixation of time and date for
each operation' as well as it determines the sequence of
operations to be followed.
3. Dispatcing
Dispatching is concerned with the starting the processes. It gives
necessary authority so as to start a particular work, which has
been already been planned under ‘Routing’ and ‘Scheduling’.
Therefore, dispatching is ‘Release of orders and instruction for
the starting of production for any item in acceptance with the
Route sheet and Schedule Charts’
4. Follow – up
Follow up which regulates the progress of materials and parts through the Production process. This closely inter elated with activities of dispatcher to whom is delegated scheduling responsibility