Unit 4_Part 1 CSE2001 Exception Handling and Function Template and Class Temp...
Low cost automation
1. Low Cost Automation
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CHAPTER 1
INTRODUCTION
1.1 Low Cost Automation- In Sight
Low Cost Automation is the introduction of simple pneumatic, hydraulic, mechanical and
electrical devices into the existing production machinery, with a view to improving their
productivity.
India is fast developing industrially. The industrial growth, particularly during the last
decade, has been considerable. This growth, of course, is not free from the attendant problems. In
a country like ours, which has mainly an agricultural based economy, the industrial development
is very likely to change the existing conditions.
In our country, one can come across' factories with outdated and inefficient technology
and also factories with modern and highly sophisticated technology. The main reason for the
latter is the fact that the latest technological developments from the already developed countries
have been transplanted is worthwhile to remember that the technological advancement that has
taken place in the developed countries has been, achieved in stages, depending upon the changed
conditions and requirements. For example many of the developments in industrially more
advanced countries require minimum labour force because of the fact that increasing wages,
shortage of skilled labour, and lower Productivity have made the older technologies~ inadequate
to meet the demands, inefficient, and uneconomical. It is- not necessary to stress here as to what
would be the result of such overnight transplantation of latest technologies from industrially
advanced countries to a developing country like ours where there is abundance of labour and also
whose social and economic conditions are different from those of many of the developed'
countries.
Consider, for example, a technology which was discontinued in a developed country
because of high labor involvement, and which (country) went in for an advanced technology
which required lesser labor. There. is no reason why an. industrial organization in a developing
country like ours should not have that (earlier) technology instead of the latest and highly
automated one. In fact, the former (technology) could be had with lesser capital investment and,
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in addition, it has the added advantage that it can provide employment to more number of people.
Besides these, the industrialization can be spread to rural areas, thereby reducing the
concentration, in a small number of cities and minimizing the social
Problems resulting there from. In addition, the demands of the market that is catered to
by the industries in a developing country may not be high. Enough to warrant huge investments
in a highly sophisticated technology.
The word Automation has run into bad weather in most of the countries. This is because,
generally, automation is considered as being represented by computerization, and which is feared
as leading to unemployment. Automation can be without computerization, and it can be very
simple also. This form of automation, which is popularly known as Low Cost Automation,
enables the industrialist to improve his manufacturing methods and efficiency without going in
for costly machinery. Low Cost Automation should not be regarded in terms of a specified
maximum capital outlay, but as an approach to automation using equipment and control
devices that are, in general, both technically and economically, within the scope of the
company concerned.
The main aim of Low Cost Automation is to increase Productivity and quality of
products and reduce the cost of production, and not reduce labor.
Even the lower level technologies can be made highly productive by automation at low
cost and in simple form.
1.2 Need of Low Cost Automation
Huge corporations with tremendous financial strength, technical leadership and
multinational market can achieve quality even in severe competition. But organizations in
developing countries with constraints on all the above, i.e. finance, technical leadership and
limited market and very low labor productivity have to achieve productivity and quality through
strategies workable under such conditions. There are many methods available to increase
competitiveness. One of the very practical, safe, economical, rewarding methods is the
application of low-cost automation (LCA).
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One of the very practical, safe, economical, rewarding methods is the application of low-cost
automation (LCA) pursued in Japan with a lot of enthusiasm from around 1960s. In India also
LCA has been found to be useful for small enterprises employing a few people to huge
manufacturing organizations employing thousands of people. Big organizations like L&T,
Siemens, Mahindra & Mahindra, Bajaj Auto, etc. made a separate cell involved in in-house
development of LCA. However, these devices were useful only to replace the muscular effort of
the labor. Developments in microelectronics started during 1970s and have added considerable
power to LCA. Electronic sensing, data acquisition, data processing and sophisticated controllers
have given an excellent combination of hi-technology at low cost. This adds considerable
intelligence into the automation system. Hence new terminology „Low cost Hi-tech automation‟
(LCHA) comes in play in 1994 to highlight the significance of the combination.
Fig 1.1 LCA Process
1.3 Automation Migration Strategy
Owing to competitive pressures in the marketplace, a company often needs to introduce a
new product in the shortest possible time. As mentioned previously, the easiest and least
expensive way to accomplish this objective is to design a manual production method, using a
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sequence of workstations operating independently. The tooling for a manual method can be
fabricated quickly and allow cost. If more than a single set of workstations is required to make
the product in sufficient quantities as is often the case. then the manual cell is replicated as many
times meet demand. If the product turns out to be successful and high future demand is
anticipated, then it makes sense for the company to automate production. The improvements are
often carried out in phases. Many companies have an automation migration strategy: that is, a
formalized plan for evolving the manufacturing system, used to produce new products as demand
grows. A typical automation migration strategy is the following
Phase 1: Manual production using single-station manned cells operating independently.
This is used for introduction of the new product for reasons already mentioned: quick and low-
cost tooling to get started
Phase 2· Automated production using single-station automated cells operating independently.
As demand for the product grows, and it becomes clear that automation can be justified, then the
single stations are automated to reduce labor and increase production rate. Work units arc still
moved between workstations manually.
Phase 3: Automated integrated production using a multistation automated system with serial
operations and automated transfer of work units between stations. When the company is certain
that the product will be produced in mass quantities; and for several years, then integration of the
single-station.
Fig 1.2 Automation Migration Strategy
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CHAPTER 2
LITERATURE REVIEW
Hui Wang, Yiming (Kevin) Rong, Hua Li , Price Shaun (1) discussed widely used in
manufacturing, fixtures have a direct impact upon product manufacturing quality, productivity
and cost, so much attention has already been paid to the research of computer aided fixture
design (CAFD) and many achievements in this field have been reported. In this paper, a
literature survey of computer aided fixture design and automation over the past decade is
proposed. First, an introduction is given on the fixture applications in industry. Then, significant
works done in the CAFD field, including their approaches, requirements and working principles
are discussed. Finally, some prospective research trends are also discussed.
Sumit Patil, Atul Patil ,Prashant Gunjawate & Ganesh Rakate (2) worked on the case study
of low cost automation for manufacturing of conveyor chain bushes and comparison of
productivity of component using conventional horizontal milling machine. In this case study, the
Low Cost Automation technique is used for manufacturing of conveyor chain bushes which
requires two flat milling operations at both ends. In this paper the following studies are carried
out 1. Reduction in cycle time due to automation, 2. Increase in productivity both qualitative and
quantitative, 3. Less human intervention, indirectly reduction in operator fatigue, 4. Less
rejection due to automatic controls and 5. Increase the profit of company with economic
justification of payback period.
M. Tolouei-Rad (3) discussed a case study has been presented where an analysis has been made
on the basis of techno-economical considerations for a typical part with three machining
operations to be produced in large quantities. It has been concluded that for the given production
task, special purpose machines would result in a significant 59% reduction of costs compared to
CNC machines, and 95.5% compared to traditional machines. The proposed methodology also
reduces the time and effort needed for decision making on utilization of special purpose
machines and determination of machine layout. In addition, it minimizes the level of expertise
required to perform these functions and eliminates possible human errors.
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CHAPTER 3
WAYS TO ACHIEVE LCA
3.1 Mechanism
The basic element of clever mechanism are comprised of structures that transforms drive energy
into motion control and equipped with two functions: motion transmission and power
transmission. One automation mechanism can be utilized for both processing and control just by
selecting the appropriate strength and material.
Motion types constituting the Basic element of clever mechanical fixture include the followings:
1. Mechanism converting rotary motion into oscillation motion
2. Mechanism converting rotary motion into linear motion
3. Mechanism converting linear motion into rotary motion
4. Intermittent rotation and reciprocating motion mechanism
5. Speed-changing, speed reduction, and quick return mechanism
6. Direction-changing mechanism
7. Boost mechanism
8. Linear and parallel motion mechanism
9. Three-dimensional motion mechanism (using a cam mechanism)
10. Power transmission mechanism
Simple automation machinery (LCA) are comprised of the following.
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Fig 3.2 Simple automation machinery
3.2 Pneumatics
Pneumatic actuators are the choice for LCA schemes in general for their ease of drive/control
and low costs, instead of complex controls and performances. Here, some application examples
of air cylinder LCA mechanism are introduced.
The examples shown are just references, and simply replicating them may not satisfy specific
load requirements and expected positioning performances. Individual user application specific
parameters and performance targets should be evaluated and appropriate designs should be
applied with the guidelines shown below.
Fig 3.2 Pneumatics Mechanism
3.3 Electromechanical Systems
As the name suggests, electromechanical systems or devices convert electrical energy
into mechanical movement – and sometimes vice versa. Most of the common electromechanical
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components, such as electric motors and solenoids are used in combination with mechanical
parts to provide actuation or movement.
Fig 3.3 Electromechanical Systems
Solenoids are used, for example, as actuators in vending machines, cash registers and
photocopiers. Electric motors, for example, are used in linear actuators (providing straight line
movement), in electric window systems, operating tables, and robotic arms.
Electric motors and gearboxes
A combination of electric motor and gearbox providing rotary actuation is one of the most
common electromechanical products. A gearbox is really a method of matching the primary
power input from a motor (high speed, low torque) to the required output (normally low speed,
high torque). (Torque can be thought of as “turning power”.)
Linear Actuator
A linear actuator is a motorized unit which often resembles hydraulic or pneumatic cylinder.
It contains a motor, gearbox and a means of converting the rotary output from the gearbox into a
powerful push-pull linear movement. This movement is normally obtained by a nut moving
along a rotating screw thread - the same means used to move the carriage on a manual lathe.
Most larger commercial linear actuators use a ball screw. This works on the same principle as a
basic nut and screw but the nut is separated from the screw by ball bearings to minimise friction.
Linear actuators are normally used to provide intermittent rather than continuous push-pull
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movements. They are self-contained units, and very easy to build into systems such as window
opening mechanisms. However, because the motor is totally enclosed, they have a limited duty
cycle. This means that they can be energised for only a certain percentage of the time. For
example, an actuator with a duty cycle of 50% means that it should only be running for only -
say - 2 minutes within a 4 minute period. Manufacturers state the precise duty cycle conditions in
their literature.
Fig 3.4 Linear Actuator
TEP linear actuator
The TEP linear actuator is an open-frame type that comes almost completely assembled.
It uses a 5mm diameter screw driven directly by a miniature DC motor. The screw engages a
brass nut
set into a plastic block which also accommodates a push rod. The end of the screw is supported
in a nylon bearing at one end of the frame and above this an identical bearing providing support
for the push rod.
Solenoids
A linear solenoid (the most common type) consists of a soft iron plunger within a coil wound
on a plastic bobbin. When current is passed through the coil, the resulting magnetic field pulls
the plunger into the coil with a considerable pulling force.
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Fig 3.5 Solenoids
These devices are relatively cheap and very simple; however, the usable stroke of a linear
solenoid is quite limited and the force exerted varies according to the position of the plunger
within the coil. When the plunger is at its extreme outside the solenoid, the pulling force is
relatively weak; as it moves towards the centre it increases.
In a rotary solenoid, a spindle turns through a specific angle - e.g. 45‟ - when the solenoid
is energized. This type of solenoid has a plunger and armature plate. The plate is separated from
the solenoid case by three ball bearings each of which runs in a small inclined plane. When the
plunger is pulled into the solenoid coil, it also turns as the ball bearings run down the inclined
planes.
MEMS (Micro-electromechanical Systems)
MEMS has been identified as one of the most promising technologies for the 21st Century
and has the potential to revolutionize both industrial and consumer products by combining
silicon based microelectronics with micromachining technology. Its techniques and microsystem
based devices have the potential to dramatically affect of all of our lives and the way we live. If
semiconductor microfabrication was seen to be the first micromanufacturing revolution, MEMS
is the second revolution.
In the most general form, MEMS consist of mechanical microstructures, microsensors,
microactuators and microelectronics, all integrated onto the same silicon chip.
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MEMS has several distinct advantages as a manufacturing technology. In the first place,
the interdisciplinary nature of MEMS technology and its micromachining techniques, as well as
its diversity of applications has resulted in an unprecedented range of devices and synergies
across previously unrelated fields (for example biology and microelectronics). Secondly, MEMS
with its batch fabrication techniques enables components and devices to be manufactured with
increased performance and reliability, combined with the obvious advantages of reduced
physical size, volume, weight and cost. Thirdly, MEMS provides the basis for the manufacture of
products that cannot be made by other methods. These factors make MEMS potentially a far
more pervasive technology than integrated circuit microchips. However, there are many
challenges and technological obstacles associated with miniaturization that need to be addressed
and overcome before MEMS can realize its overwhelming potential
3.4 Electro pneumatic systems
Electro-pneumatic control consists of electrical control systems operating pneumatic
power systems. In this solenoid valves are used as interface between the electrical and pneumatic
systems. Devices like limit switches and proximity sensors are used as feedback elements.
Electro Pneumatic control integrates pneumatic and electrical technologies, is more
widely used for large applications. In Electro Pneumatics, the signal medium is the electrical
signal either AC or DC source is used. Working medium is compressed air. Operating voltages
from around 12 V to 220 Volts are often used. The final control valve is activated by solenoid
actuation.
In Electro pneumatic controls, mainly three important steps are involved:
Signal input devices -Signal generation such as switches and contactor, Various types of
contact and proximity sensors
Signal Processing – Use of combination of Contactors of Relay or using Programmable
Logic Controllers
Signal Out puts – Out puts obtained after processing are used for activation of solenoids,
indicators or audible alarms.
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Fig 3.6 Electropnematics Systems
3.5 Hydro Pneumatic Press:
Many Industries are using manual presses like toggle presses, fly presses, arbor presses
for blanking, piercing, riveting, bending, embossing, etc., It is also used for forming two or more
components in Manufacturing Industry. Manual operation of these presses gives fatigue to the
operator, since he has to exert physical energy. Due to this the efficiency also gets lowered
down.
Considering these facts, the Hydro pneumatic press has been designed, which will reduce
the wastage of human energy and increase the production rate. We know that hydraulic system is
applied to attain precise movement. But in Pneumatics, due to the compressibility characteristic
of the air, the air cylinder tends to slow down on meeting an increase in load and to accelerate or
jump forward when working against a load which suddenly decreases. So, pneumatic actuators
are not suitable for the finer movement of the machine tool movements. These problems can be
solved by combining the two fluids – air and oil. By the use of these two media, the quick action
of air and the smooth high pressure action of oil blend ideally to provide a concept for the design
of new Hydro-Pneumatic press. It should be made clear that although the two fluids are used in
the circuit they are not to be mixed. In fact every precaution is taken to keep them separated.
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Comparison of Pneumatic and Hydraulic system:
For automation, most of the trade-offs favors pneumatic actuators since pneumatic system
have low weight and leakage co-efficient.
The most significant difference between hydraulic and pneumatic system is compressibility,
which usually signifies disadvantage.
Further, the stiffness or impedance of the pneumatic system can be controlled more easily
than with hydraulic counterpart.
Moreover, a pneumatic system allows easy energy storage. The mechanical energy for
automation can be stored as compressed air at a high pressure. A regulator can expand the stored
air to the proper working pressure.
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CHAPTER 4
AREA FOR LCA IMPLEMENTATION
4.1 Special Purpose machines
With availability of many machining processes capable of performing drilling operations
sometimes it is difficult to decide which process would result in a higher profit or a lower unit
cost for a given task. Due to increasing global competition, manufacturing industries are now
more concerned with their productivity and are more sensitive than ever to their investments with
respect to flexibility and efficiency of production equipment. Researchers believe that increasing
the quality of production and reducing cost and time of production are very important factors in
achieving higher productivity. Achieving this goal requires reconsidering current production
methods that could lead to introduction of new production techniques and more advanced
technologies.
The modular principle is very popular in the design of many products such as automobile,
home appliances, information devices, industrial equipment, etc. This trend can be considered as
one of the great contributions of modular design of machine tools to those working in other
industries
Groover has defined the term “production automation” as the application of electrical,
electronic, mechanical, hydraulic and pneumatic systems for rapid and quality productions in
large volumes. Automated production techniques are widely used in manufacturing industries for
dealing with issues such as high cost of labor, shortage of skilled people, low interest of labor to
work in production firms, safety, high cost of raw materials, improved quality, uniformity in the
quality of products, low inventory, customers satisfaction, and performing difficult operations.
4.2 Computer Aided Fixture Design
Along with much work being carried out to develop an efficient CAFD system, fixture
design systems can be categorized into three main categories based on their degree of
automation; i.e. fully automated, semiautomated and interactive class. The fully automated and
semi-automated fixture design systems based are established through incorporating the
experience and knowledge of designers into rules and algorithms in order to automate the
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selection of fixturing elements and locating points. Interactive fixture design module enables
designers to select the fixturing faces, points and elements for fixture structure.
At the initial stage of CAFD two decades ago, The earliest research mainly developed the
interactive CAFD systems, based upon an understanding of workpiece and process information.
These systems usually provide fixture designers rules to evaluate the design and a list of
components to be used empirical device, which is often used to help fixture designer in
interactive environments to achieve a complete fixture design solution especially for fixture
configuration designs. In majority of these approaches, several IF-THEN rules are created based
on design knowledge to lead the design process. Then, the solution of design in the interactive
process of fixture design would be determined using created rules through a prearrange set of
questioning-answering actions. Though, there are usually some difficulties for reasoning
procedure mostly in case of constructing the logic tree and also sufficient comprehensive rule set
which affect highly on the design result quality as well as efficiency of the design. Moreover, the
reasoning procedure is also
Accordingly, some researchers have proposed semiautomated fixture design systems by using
combined fixture design knowledge and existing fixture design experience. Those methods
mostly applied case based reasoning technique to solve fixture planning and fixture unit design .
These systems are mostly constructed based on the assumption that „similar workpieces have
similar fixture designs. Therefore, by discovering the similar workpiece in database, the proper
fixture design is retrieved from database and then is used for new workpiece. To improve the
performance of existing systems, some other intelligent techniques are combined with CBR such
as Rule Based Reasoning (RBR), fuzzy logic, Model Based Design, GA, Neural Network (NN)
and so on to facilitate and automate more steps of fixture design such as layout planning,
verification.
Many researches related to fixture design have concentrated on the micro aspects of fixture
design on the matter of fixture design automation which are referred to singular problems e.g.
deformation analysis, stability evaluation, fixture repeatability, tolerance analysis, geometric
reasoning and so on.
The smart fixtures can perceive the design environment by themselves and drive themselves to
complete appropriate design activities automatically. As mentioned before, most of the existing
fixture design methods are able to solve micro design problems automatically that are mainly
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constructed based on optimization techniques. Now comprehensive fixture design systems,
which are established based on integrating those methods to help solving fixture design
problems automatically, is needed .
4.3 Automated storage system
Application:
Automated storage systems are used to supply and feed unmachined parts and workpieces
into the machine tool. These modular magazines are often positioned next to the machine.
They can, however, be integrated directly into machine tools.
They are especially suitable for flexibly interlinking machines.
By virtue of their attributes, the automated storage systems are designed specifically for
self-service by CNC machines, which depend on workpiece interchange within the
movement range of the spindle. These magazines are suitable for both gantry machine
centres, for cross-table machines and for machines with tables that execute the movement
in the X-axis.
These magazines are the ideal solution for shafts and cubic components, as well as for
cast or molded components.
Pallets or fixtures can also be stored. The permitted dimension of the components
depends on the magazine size, which is largely freely selectable.
Features:
The automated storage system can be adapted to suit different spaces, as it can have any
number of direction changes.
To bring the components into the gripping range of the machine tool, a magazine moves
temporarily into the working range of the spindle.
The protected magazine guide is so smooth-running that the magazine only has to be
shielded at the point of transition to the machine tool. The result is an affordable solution
which also allows access to the work pieces at all times.
The pneumatically driven automated storage system is controlled by the machine control
via 3 to 5M-commands.
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The components can be positioned on the magazine in a flat or a stacked arrangement.
Shape and contour masks or stack and stop elements are ideal for fastening.
Advantage:
- Very high component stocking density
- Quick and simple component access
- Simple control via M-commands
- Highly flexible in terms of shape and dimensions
- Suitable as a magazine and/or transport unit
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CHAPTER 5
CASE STUDY
Low Cost Automation for Manufacturing of Conveyor Chain Bushes
The component for which low cost automation carried out is a bush for chain conveyors.
These chain conveyors are used in sugar industries and other process industries for material
handling purposes. Dimensions of bush vary according to design of conveyors but basic
geometry of all bushes remains same. Figure shows the basic geometry of bush.
Fig 5.1 Conveyor Bushes
Four milling operations (two at both ends which are diametrically opposite to each other)
are required to be carried out on work piece to manufacture bush. In earlier process of
manufacturing the bushes were machined by using conventional horizontal milling machine with
appropriate fixture. By using conventional process only two side milling operations were
performed on each bush at a time and all job setting and machining activities carried out
manually. To rectify these drawbacks low cost automation project is designed and developed by
following USA approach of automation and process improvement.
The new developed system consists of use gang milling system. Four side milling
operations which require two setups for each job should possible to manufacture in a single
setup. Machine includes automatic clamping, de-clamping and feed providing system. Machine
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is capable to manufacture all types of bushes with minor changes in tool setting and fixture
setup.
Design calculations of various parts are made by following engineering principles and
technical information. Parts are designed to meet functional requirements and also DFM and
DFMA principles keeping in mind. The final outcome of the design process consists of
description of system in the form of drawings of assemblies and individual components. Various
two-dimensional (2-D) and three dimensional (3-D) geometric drawings are prepared by using
Solid Works CAD software.
MECHANISM OF SPM
Mechanism of new developed automation system consists of –
1. Two vertical spindle milling heads with two cutters on each for performing four side milling
operations simultaneously in single setup.
2. Lead screw mechanism for providing feed to milling head column.
3. Hydraulic mechanism for providing automatic feed to work table and for automatic clamping
and de-clamping of work holding fixture.
4. Mechatronics means for controlling and synchronizing various hydraulic cycles, limit switches
signal system and manufacturing operations. Subassemblies of automation system are discussed
further along with three dimensional views prepared in Solid Works CAD software
.
Figure 5.2 : Headstock assembly Figure 5.3 : Dovetail slide assembly
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Figure 5.4 : Slide assembly Figure 5.5 : Fixture assembly
Operation Sequence
Fig 5.6 Process for case study
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CONCLUSION
Production quality and low production cost are essential for the success of manufacturers
in today‟s competitive market. The purpose of this study is to identify use of Low cost
automation industry .Considerable improvement in productivity both qualitative and quantitative
is observed with all other benefits of automation. Work is in progress to integrate it with a 3D
CAD modelling system. The information could be directly extracted from the CAD system,
eliminating the need for manual data input by user.
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REFERENCES
[1] Hui Wang, Yiming (Kevin) Rong, Hua Li , Price Shaun, “Computer aided Fxture design”,
Sciencedirect.
[2] Sumit Patil, Atul Patil ,Prashant Gunjawate & Ganesh Rakate , “Low Cost Automation for
Manufacturing of Conveyor Chain Bushes” ,IOSR Journal of Engineering (IOSRJEN) page 2-5
[3] M. Tolouei Rad. “An intelligent approach to high quantity automated machining”, Journal of
Achievement in material and manufacturing engineering, volume 47; issue 2; August 2011; 195-
204.
[4] Mikell P. Groover. Automation, Production Systems, and Computer – Integrated
Manufacturing, Third Edition. Prentice-Hall (2008); ISBN-978-81-203-3418- 2; 15-18.