The Various Types of Production Systems and Their Importance
The Various Types of Production Systems and Their Importance
The Various Types of Production Systems and Their Importance
ON
IMPORTANCE OF
PRODUCTION SYSTEMS
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INDEX
1) Introduction
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INTRODUCTION
(iii) Output is goods and services (e.g. products, parts, paper work, served
customers etc.
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The combination of operations and activities stated above employed
to create goods and services are known as manufacturing system. A
manufacturing system therefore may be looked upon as an independent
group of sub-systems, each sub-system performing a distinct function.
Different sub-systems may perform different functions, yet they are inter-
related and require to be unified to achieve overall objectives of the
organization.
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FACTORS INFLUENCING CHOICE OF
MANUFACTURING SYSTEM
There is no best manufacturing system for any product. The choice of the
system depends on various circumstances but it must meet two basic
objectives, namely -
(i) It must be able to meet the specifications of the final product, and
(ii) It must be cost effective
The product specifications can be met by choosing the right technology but
that is not always an easy task. Since stricter specifications add to the cost of
the product, there is always a trade off between the desired specifications
and the cost to achieve such specifications. For example, sophisticated
injection moulding machines and high quality plastics can produce excellent
dolls cheaply provided they are produced in volume. However, if their
demand is limited, they may not be able to compete with “home made” dolls
produced in small quantities and sold at a fraction of the price of the
moulded version.
Various factors which determine the choice of the manufacturing process are
as follows:
(a) Effect of volume/variety
One of the major considerations in the process selection is the
volume/variety of the products.
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High product variety require highly skilled labour, general purpose
machines, detailed production planning and control system.
On the other hand low product variety (i.e. one or few products produced in
large volumes) enables the use of low skilled labor, highly automated mass
production processes using special purpose machines and simple production
planning and control systems.
Fig. exhibits the relationship between output and the transformation process.
The horizontal axis shows the degree of repetitiveness represented in terms
of batch size, one end showing the products produced in batches of one and
other end representing products produced in very large batch sizes.
The vertical axis represents the transformation process, the top representing
the project form where each project is followed by another (no two projects
being alike) and the bottom representing the process form where the single
product with highly continuous material flow (e.g. as in refinery, sugar mill)
is produced.
Shaded area in each bar suggests the manufacturing system desirable for the
indicated volume. Unshaded area in the lower portion of the column implies
that it is inadvisable to use the continuous form when the batch is really
small. Similarly, when the batch is really large, it is not at all advisable to
use the project form.
For these reasons, decisions involving process selection must be taken while
formulating the corporate strategy of the firm
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Effect of volume on manufacturing process selection
(c)Flexibility
Flexibility implies the ability of the company to satisfy varied customers
requirements. Flexibility and product variety are inter-related. If more
variety is to be manufactured, the manufacturing facilities will have to be
commonised and depending upon the volume, the extent of commonalities
will require to be justified. Greater commonalities demands intermittent
manufacturing which is associated with higher inventories, large
manufacturing lead times and elaborate planning and control.
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(e)Efficiency
Efficiency measures the speed and the cost of the transformation process.
Efficiency is the greatest when the product is mass producted. But to mass
produce a product, greater sales volumes are required. Therefore, depending
upon the sales volume, product variety will have to be considered and the
process which will give the best efficiency in terms of machine and
manpower utilization will have to be selected.
(f)Environment
Environment brings in new technologies and forces the adoption of new
process of manufacturing. For example, wooden furniture is gradually being
replaced by metals and plastic. A furniture manufacturing unit will have to
change its technology (i.e. change from one off production to batch
production) to fall in line with changing times. Similarly, as market
preferences change due fashions or other reasons, the manufacturing process
has to be changed accordingly.
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CLASSIFICATION OF
MANUFACTURING SYSTEMS
INTERMITTENT SYSTEM
In this system, the goods are manufactured specially to fulfill orders made
by customers rather than for stock. Here the flow of material is intermittent.
Intermittent production systems are those where the production facilities are
flexible enough to handle a wide variety of products and sizes. These can be
used to manufacture those products where the basic nature of inputs changes
with the change in the design of the product and the production process
requires continuous adjustments. Considerable storage between operation is
required, so that individual operations can be carried out independently for
further utilization of men and machines. Examples of intermittent system
are: machine shops, hospitals, general office etc.
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Chief characteristics of intermittent system are: -
(i) Most products are produced in small quantities
(ii) Machines and equipment are laid out by process.
(iii) Workloads are generally unbalanced.
(iv) Highly skilled operators are required for efficient use of machines and
equipment.
(v) In-process inventory is large.
(vi) Flexible to suit production varieties.
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Intermittent systems can be further classified into two categories, namely
CONTINUOUS SYSTEM
In this system the items are produced for the stocks and not for specific
orders. Before planning manufacturing to stock, a sales forecast is made to
estimate likely demand of the product and a master schedule is prepared to
adjust the sales forecast according to past orders and level of inventory. Here
the inputs are standardized and a standard set of processes and sequence of
processes can be adopted. Due to this routing and scheduling for the whole
process can be standardized.
After setting of master production schedule, a detailed planning is carried
on. Basic manufacturing information and bills of material are recorded.
Information for machine load charts, equipment, personnel and material
needs is tabulated. In continuous manufacturing systems each production run
manufactures in large lot sizes and the production process is carried on in a
definite sequence of operations in a pre-determined order. In process storage
is not necessary which in turn reduces material handling and transportation
facilities. First in first out priority rules are followed in the system. In short,
here the input-output characteristics are standardized allowing for
standardization of operations and their sequence.
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Production Control Mechanism for Continuous
manufacturing system: -
In this system the control mechanism is not as elaborate and complex as for
intermittent system. In continuous system large quantities of standardized
products are produced using standardized production process.
(i) This system does not involve diverse work, due to which routing
standardized route and schedule sheets are prepared.
(ii) In case of standard products meant for mass production, master route
sheets are prepared for more effective co- ordination of various departments.
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INTERMITTENT PRODUCTION
SYSTEM
PROJECT PRODUCTION
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(D) Personnel problems
Project production has many personnel related problems namely:
• When there is a fast build up, staff is either borrowed from other
departments or hired for short duration. Therefore, personnel involved in the
project have limited (or short lived) interest in the project.
• Since each project has a limited duration, the staff starts spending more
time forgetting prepared for the next project.
•Site for the project may be in the underdeveloped region and it may change
from project to project which causes dislocation of the normal life.
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JOB PRODUCTION
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(D) Materials are indented and purchased on receipt of orders unlike in batch
or mass production where material requirements are planned well in
advance.
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(D) Highly skilled labour
The labor force is usually highly skilled-highly qualified trade apprentices
who are expected to work from minimum instructions. Instructions
regarding “what to make” are issued in the form of specifications while
instructions as to “how to manufacture” are usually oral. The workmen
being highly skilled are expected to work independently and display a great
deal of initiative and judgment. They are required to set up their own
machines and prepare their OW special tools or production aids in order to
further the manufacture of a part or a assembly.
(E) Highly competent knowledgeable supervision
Highly competent general engineers are engaged as foreman in the base
workshop and a group of site engineers, practical men, with thorough
training, capable of taking independent charge of each contract are employed
to work at site. Therefore, these engineers (supervisors) in a jobbing
production are the reservoir of job knowledge. The supervisor besides being
able administrator is expected to improvise and determine best work
methods, determine tool requirements, select the best process and provide
management with reliable estimates of labor and materials for specific
orders. The span of control - the number of workmen to be supervised by a
supervisor - is kept low because of technical nature of the job.
(F) Simple Mechanism
Tools control function is simple. Standard tools are stocked while special
tools are either made on the shop floor by the operators or purchased on
request from supervisor.
(G) Decentralized Process
The scheduling activity is more or less decentralized. A schedule is prepared
to show the start and completion date of each major component of the
product. Job tickets giving completion date of each component are raised
and given to the shop. The activity of day to day scheduling is left to the
individual shop supervisor.
EXAMPLE OF JOB PRODUCTION SYSTEM
Job production involves firms producing items that meet the specific
requirements of the customer. Often these are one-off, unique items such as
those made by an architect or wedding dressmaker. For an architect, each
building or structure that he designs will be different and tailored to the
needs of each individual client.
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With job production, a single worker or group of workers handles the
complete task. Jobs can be on a small-scale involving little or no technology.
However, jobs can also be complex requiring lots of technology.
Hairdressers
Tailoring
High technology jobs are much more complex and difficult. These jobs need
to be very well project-managed and require highly qualified and skilled
workers. Examples of high technology / complex jobs include:
Film production
ADVANTAGES
The advantage of job production is that each item can be altered for the
specific customer and this provides genuine marketing benefits. A business
is likely to be able to ‘add value’ to the products and possibly create a
unique selling point (USP), both of which should enable it to sell at high
prices.
DISADVANTAGES
Whether it is based on low or high technology, Job production is an
expensive process as it is labour intensive (uses more workers compared to
machines). This raises costs to firms as the payment of wages and salaries is
more expensive than the costs of running machines.
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BATCH PRODUCTION
Time between batches is known as 'Down Time' where the factory would
make seasonal items or consumables such as toasters where no one can
predict the quantity needed.
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There are several advantages of batch production; it can reduce initial capital
outlay because a single production line can be used to produce several
products. As shown in the example, batch production can be useful for small
businesses who cannot afford to run continuous production lines. Also,
companies can use batch production as a trial run. If a retailer buys a batch
of a product and people do not buy them then the producer can cease
production without having to sustain huge losses. Other types of production
include: assembly line, job production, continuous, cell, and project.
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work tend to queue up at different machines due to differing cycle times,
batch sizes and sequence of operations.
(E) Large work-in-progress
Work in progress is comparatively large due to varying work content of
different components, imbalances in manufacturing times, formation of
queues between the machines.
(F) Need to have production planning and control
Functions of production planning and control in a batch production unit are
more complex than those in jobbing production or mass and flow
production.
• Materials control and tools control functions are important. Scientific
stock-control system needs to be used to ensure routine replenishment.
• Detailed operational layouts and route sheets are prepared for each part of
the product.
• Lo and scheduling needs to be more detailed and more sophisticated since
every machine requires to be individually scheduled.
• Progressing function is very important to collect information on progress
of work.
A separate progress card needs to be maintained to record progress of each
component.
• Expediting is generally necessary since quite often jobs, due to imbalances
in work content, tend to lag behind.
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Simpler machine set-ups may be performed by the operator but those
involving complex operations arc set by the separate machine setter.
(C) Limited span of control
The amount of supervision required in batch production is lower than that of
jobbing production and is dependent of the batch size. The ratio of direct
workmen to supervisors is more or less a function of batch size. The smaller
the batches, the lower are the ratio of direct workers to supervisors, and vice-
versa. This is because smaller lots require each supervisor to spend a great
deal of their time in allocating new work, giving instructions, follow up n
the shop floor for proper movement of materials from and to the machines,
identifying delays and interruptions, and arranging, in consultation with
planning, work load in his section to keep his men busy.
(D) Flexibility of production schedules
Disruptions due to machine breakdowns or absenteeism do not seriously
affect production as another machine can be used or another operator from
another machine can be shifted.
For example when a bakery bakes loaves of wholemeal bread, a large ball of
wholemeal dough will be split into several loaves which will be spread out
together on a large baking tray. The loaves on the tray will then together be
cooked, wrapped and dispatched to shelves, before the bakery starts on a
separate batch of, for example, crusty white bread. Note that each loaf is
identical within a batch but that loaves can vary from batch to batch.
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Batch production is a very common method of organising manufacture. Good
examples include:
Cereal farming
ADVANTAGES
The batch method can be an advantage for businesses that produce a range of
products. It is cheaper to produce a number of each item in one go because
machines can be used more effectively, the materials can be bought in bulk and
the workers can specialize in that task. There are two particular advantages of
workers being able to concentrate their skills.
They should become more expert at their tasks, which will in turn increase
productivity (output per worker). This will lower costs, as fewer workers are
needed to produce a set amount.
Better quality products should be produced as workers are more familiar with
the task and so can find ways of improving it.
DISADVANTAGES
Batch production requires very careful planning to decide what batch will be
produced when. Once a batch is in production it is difficult to change, as
switching to another batch takes time and will mean a loss of output. Batch
methods can also result in the build up of significant “work in progress” or
stocks (i.e. completed batches waiting for their turn to be worked on in the next
operation). This increases costs as it takes up space and raises the chance of
damage to stock.
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CONTINUOUS PRODUCTION
SYSTEM
MASS PRODUCTION
Standardization is the fundamental characteristic of this system. Here items
are produced in large quantities and much emphasis is not given to
consumers orders. In fact the production is to stock and not to order.
Standardization is there w.r.t. materials and machines. Uniform and
uninterrupted flow of material is maintained through pre determined
sequence of operations required to produce the product. The system can
produce only one type of product at one time.
These days, mass production system is generally used to manufacture sub-
assemblies or particular parts/components of an item. These parts are
assembled together by the enterprise to get the final product. One distinct
advantage of this approach is that different combinations of sub-assemblies
or parts can be used to manufacture different kinds of products.
Specialization and standardization in manufacturing single component also
leads to economies in production and product diversification to meet specific
demands of consumers.
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devices such as the woodworking lathe had existed for centuries, their
translation into industrial machine tools capable of cutting and shaping hard
metals to precise tolerances was brought about by a series of 19th-century
innovators, first in Britain and later in the United States. With precision
equipment, large numbers of identical parts could be produced at low cost
and with a small work force.
The assembly line. Though prototypes of the assembly line can be traced
to antiquity, the true ancestor of this industrial technique was the 19th-
century meat-packing industry in Cincinnati, Ohio, and in Chicago, where
overhead trolleys were employed to convey carcasses from worker to
worker. When these trolleys were connected with chains and power was
used to move the carcasses past the workers at a steady pace, they formed a
true assembly line (or in effect a "disassembly" line in the case of meat
cutters). Stationary workers concentrated on one task, performing it at a pace
dictated by the machine, minimizing unnecessary movement, and
dramatically increasing productivity.
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stimulated Ford to apply the technique to chassis assembly. Under the old
system, by which parts were carried to a stationary assembly point, 12 1/2
man-hours were required for each chassis. Using a rope to pull the chassis
past stockpiles of components, Ford cut labour time to six man-hours. With
improvements--a chain drive to power assembly-line movement, stationary
locations for the workmen, and work stations designed for convenience and
comfort--assembly time fell to 93 man-minutes by the end of April 1914.
Ford's methods drastically reduced the price of a private automobile,
bringing it within the reach of the common man. (see also Index: automotive
industry ) Ford's spectacular feats forced both his competitors and his parts
suppliers to initiate his technique, and the assembly line spread through a
large part of U.S. industry, bringing dramatic gains in productivity and
causing skilled workers to be replaced with low-cost unskilled labour.
Because the pace of the assembly line was dictated by machines, the
temptation arose to accelerate the machines, forcing the workers to keep up.
Such speedups became a serious point of contention between labour and
management, while the dull, repetitive nature of many assembly-line jobs
bored employees, reducing their output.
In the 1970s and '80s some countries, particularly in Asia and South
America, that had hitherto been largely agricultural and that had imported
manufactured goods began industrializing. The skills needed by workers on
assembly-line tasks were easily acquired, and standards of living in these
developing countries were so low that wages could be kept below those of
the already industrialized nations. Many large manufacturers in the United
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States and elsewhere therefore began "outsourcing"--that is, having parts
made or whole products assembled in developing nations. Consequently,
those countries are rapidly becoming integrated into the world economic
community.
In a factory for a complex product, rather than one assembly line, there may
be many auxiliary assembly lines feeding sub-assemblies (i.e. car engines or
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seats) to a backbone "main" assembly line. A diagram of a typical mass-
production factory looks more like the skeleton of a fish than a single line.
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(F) Limited work- in- progress
Work-in-progress is comparatively less since the manufacturing line is
balanced.
EXAMPLE OF MASS PRODUCTION SYSTEM
Flow production involves a continuous movement of items through the
production process. This means that when one task is finished the next task
must start immediately. Therefore, the time taken on each task must be the
same.
ADVANTAGES
Flow production is capital intensive. This means it uses a high proportion of
machinery in relation to workers, as is the case on an assembly line. The
advantage of this is that a high number of products can roll off assembly
lines at very low cost. This is because production can continue at night and
over weekends and also firms can benefit from economies of scale, which
should lower the cost per unit of production.
DISADVANTAGES
The main disadvantage is that with so much machinery it is very difficult to
alter the production process. This makes production inflexible and means
that all products have to be very similar or standardized and cannot be
tailored to individual tastes. However some “variety” can be achieved by
applying different finishes decorations etc at the end of the production line.
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PROCESS PRODUCTION
The layout of plant, shape and size of its buildings, location of services and
storage yards, position of cranes and conveyors is such that material flow is
unidirectional and at the steady rate. Special purpose machinery and
equipment with built-in controls to measure output and regulate input are
employed to suit the needs.
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JUST-IN-TIME PRODUCTION SYSTEM
(JIT)
Introduction: Just in Time manufacturing is a systems approach to
developing and operating a manufacturing system. It is based on the total
elimination of waste. JIT is not a new concept. It has been part and parcel of
the Japanese manufacturing industry adopted approach for quite some time.
It requires that equipment, resources and labor are made available only in the
amount required and at the time required to do the job. It is based on
producing only the necessary units in the necessary quantities at the
necessary time by bringing production rates exactly in line with market
demand. In short, JIT means making what the market wants, when it wants
it. JIT has been found to be so effective that it increases productivity, work
performance and product quality, while saving costs.
Partnerships
In the past companies were capable of remaining independent and
competitive when they had the capability and resources necessary to produce
a product. This is no longer possible. As technology increases in complexity,
companies overcome capital limitations or labor intensive requirements by
becoming dependent on suppliers to provide services. Many services and
Original Equipment Manufacturing (OEM) suppliers have evolved as the
result. Companies now appreciate that long-term success relies on the
quality of the customer-supplier relationship established so that they will
develop successful partnerships. Hence, successful partnerships require the
development of mutually beneficial programs.
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Contracts Supporting Partnerships
By ensuring fair and equitable contracts, many of the problems in
developing customer-supplier relationships are overcome by JIT
manufacturers. The goal of JIT is to make long-term contracts with
suppliers. Long-term contracts usually extend for one or more years and can
consist of one or more part requirements
Goals
Secure a steady flow of quality parts.
Reduce the lead time required for ordering product.
Reduce the amount of inventory in the supply and production pipe lines.
Reduce the cost of purchased material.
Objectives
Improve purchasing efficiency.
Improve quality and delivery performance of suppliers.
Isolate factors that influence the cost of material.
Remove unnecessary cost factors in the materials supply system.
Tactics
Regard suppliers as an extension of the internal manufacturing process and
cultivate them as long term business partners.
Establish long term purchasing and supply commitments.
Improve communication with suppliers.
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Involve suppliers in early stages of new product planning.
Use supplier expertise to improve design manufacturability and reduce
product cost.
Performance measures
To achieve continued improvement, a company must measure the
performance levels of its smallest processes against its optimum values. This
is accomplished by having performance measures visible to all levels in a
company. The use of control charts is one of the best ways to show the
collected performance measures.
Conclusion
Hence we can see that to have a Total JIT manufacturing system, a
company-wide commitment, proper materials, quality, people and
equipments must always be made available when needed. In addition; the
policies and procedures developed for an internal JIT structure should also
be extended into the company's supplier and customer base to establish the
identification of duplication of effort and performance feedback review to
continuously reduced wastage and improve quality. In general, it can be said
that there is no such thing as a KEY in achieving a JIT success; only a
LADDER; where a series of continuous steps of dedication in doing the job
right every time is all it takes.
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