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SUB CODE: 12062
COMPUTER AIDED DESIGN AND MANUFACTURING
N.P.R. POLYTECHNIC COLLEGEN.P.R. POLYTECHNIC COLLEGEN.P.R. POLYTECHNIC COLLEGEN.P.R. POLYTECHNIC COLLEGE
NATHAM NATHAM NATHAM NATHAM –––– 624 401.624 401.624 401.624 401.
E E E E –––– LEARNING MATERIALLEARNING MATERIALLEARNING MATERIALLEARNING MATERIAL
MECHANICAL ENGINEEIRNG
(VI - SEMESTER)
Reach the Stars
ISO 9001:2008
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SYLLABUS
COMPUTER AIDED DESIGN AND MANUFACTURING
Subject Code: 12062
UNIT TOPIC
I Computer Aided Design and Geometric Modeling
II Computer Aided Manufacturing
III CNC Machines
IV CNC Components and Part Programming
V GT-FMS-CIM-AGV and Robotics
UNIT – I
COMPUTER AIDED DESIGN AND GEOMETRIC MODELING
Introduction – CAD definition – Shigley’s design process – CAD activities –
benefits of CAD – CAD hardware : Input / Output devices – CRT – raster
scan & direct view storage tube – LCD, plasma panel, mouse, digitizer,
image scanner, drum plotter, flat bed plotter, laser printer – secondary
storage devices : hard disks, floppy disks, CD, DVD, flash memory.
Types of CAD system: PC based CAD system – workstation based CAD
system – graphics workstation – configuration and typical specification –
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CAD software packages – AutoCAM – computer networking: purposes –
topology – types – OSI networking standards – protocols (description
only).
Geometric modeling techniques: wire frame, surface, solid modeling –
graphics standards: Need, GKS – IGES – DXF.
Introduction to finite element methods – procedure of finite element
analysis (brief description only).
UNIT – II
COMPUTER AIDED MANUFACTURING
CAM definition – functions of CAM – benefits of CAM – integrated
CAD/CAM organization – process planning – master data – structure of a
typical CAPP – types of CAPP : variant type, generative type – advantages
of CAPP - aggregate production planning – Master Production Schedule
(MPS) – capacity planning – Materials Requirement Planning (MRP) –
introduction to enterprises resources planning –Manufacturing Resources
104 Planning (MRP-II) – just in time manufacturing philosophy – cost
involved in design changes – concept of Design for Excellence (DFX) –
guide lines of Design for Manufacture / Assembly (DFM/A). NC part
programming – manual programming – tape format : sequence number,
preparatory functions and G codes, miscellaneous functions and M codes
– CNC program procedure – coordinate system – types of motion control:
point-to-point, paraxial and contouring - NC dimensioning – reference
points – machine zero, work zero, tool zero and tool offsets.
UNIT-III
CNC MACHINES
Numerical control – definition – components of NC systems –
development of NC – DNC – CNC and adaptive control systems – working
principle of a CNC system – distinguishing features of CNC machines -
advantage of CNC machines – difference between NC and CNC – types of
turning centre: horizontal, vertical – types of machining centers:
horizontal spindle, vertical spindle, universal machines – machine axis
conventions – design considerations of NC machine tools.
CNC EDM machine – Coordinate measuring machines: construction,
working principles and specifications – maintenance of CNC machines.
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UNIT-IV
CNC COMPONENTS AND PART PROGRAMMING
Drives: spindle drive – hydraulic systems – direct-current motors –
stepping motors – servo motors – AC drive spindles - slide ways – linear
motion bearings – recirculation ball screw – ATC – tool magazine -
feedback devices: encoders – linear and rotary transducers – in-process
probing.
Part Program – tool information – speed – feed data – interpolation –
macro – subroutines – canned cycles – mirror images – thread cutting –
sample programs for lathe and milling – generating CNC codes from CAD
models – post processing – conversational programming – APT
programming.
UNIT-V
GT-FMS-CIM-AGVAND ROBOTICS
Product Development Cycle – sequential engineering – concurrent
engineering – rapid proto typing: concept and applications – 3D printing.
Group Technology(GT) – concept of part family – parts classification and
coding – coding structure – MICLASS – OPITZ – benefits of GT.
FMS & CIM – introduction to FMS – types of manufacturing - FMS
components – FMS layouts – types of FMS : flexible manufacturing cell –
flexible turning cell – flexible transfer line – flexible machine systems –
benefits of FMS - concept of CIM – historical background –- CIM hardware
– CIM software – CIM wheel - introduction to intelligent manufacturing
system – virtual machining.
Integrated material handling – AGV: working principle and benefits –
Automatic Storage and Retrieval Systems (ASRS).
ROBOT – definition – robot anatomy and classifications – robot
configurations – industrial applications: characteristics, material transfer,
machine loading, welding, spray coating, assembly and inspection
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Text Books:
1.CAD/CAM/CIM, R.Radhakrishnan, S.Subramanian, V.Raju, 2nd, 2003,
New Age International Pvt. Ltd.
2. CAD/CAM, Mikell P.Groover, Emory Zimmers Jr. Indian Reprint Oct
1993, Prantice Hall of India Pvt., Ltd.
3. S.K.Sinha, NC Programming, I Edition, 2001, Galgotia Publications Pvt.
Ltd.
Reference Books
1. Dr.P.N.Rao, CAD/CAM Principles and Applications, 2002, Tata Mc Graw Hill
Publishing Company Ltd.
2. Ibrahim Zeid, Mastering CAD/CAM, Special Indian Edition 2007, Tata
McGraw-Hill Publishing Company Ltd., New Delhi.
3. Mikell P. Groover, Automation, Production Systems, and Computer-
Integrated Manufacturing, 2nd Edition, Reprint 2002, Pearson Education
Asia.
4. Yoram Koren, Computer control of manufacturing systems, International
Edition 1983, McGraw Hill Book Co
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UNIT – I
COMPUTER AIDED DESIGN & GEOMETRIC MODELLING
DEFINITION OF CAD:
CAD is the Acronym for computer-aided design/computer-aided manufacturing, computer systems
used to design and manufacture products. The term CAD/CAM implies that an engineer can use
the system both for designing a product and for controlling manufacturing processes. For example,
once a design has been produced with the CAD component, the design itself can control the
machines that construct the part.
Activities of CAD
a) Geometric modeling:
Geometric modeling is concerned with the computer capatible mathematical description of the
geometry of an object to be designed. The mathematical description allow s the image of the
object to be displayed and manipulated on a graphics terminal. The CAD software provides the
geometric modeling capabilities
b) Engineering analysis:
For any engineering design, some type of analysis is required. The analysis may involve stress-
strain calculations heat transfer calculations, the use of differential equations to describe the
dynamic behavior of the system being designed. The computer can be used to aid in this analysis
work.
c) Design review and evaluation:
(i) Dimensioning and tolerance routines
(ii) Layering: Overlaying the geometric image of the final shape of the machine part on the top of
the image of the rough casting. This ensures that sufficient material is available on the casting to
accomplish the final machining operations.
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(iii) Interference checking: This involves the analysis of an assembled structure in which there is a
risk that the components of the assembly may occupy the same space.
(iv) Kinematics: The available kinematics packages provide the capability to animate the motion of
simple designed mechanisms such hinged components and linkages
Wire frame Modeling
A wire frame model is a collection of curve segments in 3D space. It is usually meant for a
surfaced structure or a solid object because a wire frame needs smaller storage and is easier to
handle compared with surface or solid models.
But wire frame models have no surface data in it. So, it needs to be converted into surface model
for the purpose of various operations in the computer (e.g. computer graphics, structural analysis,
collision detection, process planning, etc.)
Advantages of Wire frame model
1. Simple to construct
2. Designer needs little training
3. System needs little memory
4. Take less manipulation time
5. Retrieving and editing can be done easy
6. Consumes less time
7. Best suitable for manipulations as orthographic isometric and perspective views.
Disadvantages of Wire frame model:
1. Image causes confusion
2. Cannot get required information from this model
3. Hidden line removal features not available
4. Not possible for volume and mass calculation, NC programming cross sectioning etc
5. Not suitable to represent complex solids
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Operation of CRT
The cathode-ray tube (CRT) is one of the main elements of an oscilloscope. The tubes are
produced with electrostatic and electromagnetic control, where electrostatic or magnetic fields
deviate the electron beam respectively. Animation shows the principle scheme of CRT with
electrostatic control as well as the motion of the electrons in the beam drawing a sinusoid on the
screen of oscilloscope. CRT consists of the glass bulb evacuated to a high vacuum, the cathode (a
source of electrons), cathode heater, electrodes for brightness and focus control, several
accelerating anodes, the pairs of horizontal and vertical capacitor plates deviating the electron
beam, and fluorescing screen. One of anodes, which accelerate the electrons, is placed close to the
screen.
The high positive voltage is applied to this electrode. Under the action of the applied voltage the
electrons are moved with acceleration from cathode to anode. In the absence of the voltage
applied to deviating plates of the capacitor the electron beam will be incident on the screen in the
center brightening a point in the fluorescing layer. In oscilloscope the analyzed signal after
amplification is applied to vertical deviating plates, while the periodic saw tooth signal is applied to
horizontal plates.
As a result the electron beam "draws" the dependence of the investigated signal on time on the
screen of the tube. Reaching the right side of the screen the beam has to be returned to an initial
point at the left side. Thus, if CRT is not blanked during this retrace, then the beam will leave a
track crossing the image of investigated signal. For this reason, during retrace a negative voltage
is applied to control electrode situated near to cathode and electrons are locked by such a way at
the electron gun. As a result, the electron beam will be discontinuous,
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UNIT - II
Computer Aided Manufacturing
CAM Definition
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.(Computer-Aided Manufacturing) The automation of manufacturing
systems and techniques, including numerical control, process control, robotics and materials
requirements planning.
Applications of Computer-Aided Manufacturing
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 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.
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For the sake of convenience, a single computer ‘controller’ can drive all of the tools in a single cell.
G-code instructions can be fed to this controller and then left to run the cell with minimal input
from human supervisors.
Fig (CAM Model)
Benefits of CAM
• Safeguard design intent by eliminating all redrawing of geometry. Making CAM functionality
available from within solid-modeling systems ensures that even the subtlest engineering change
will not be overlooked. Programmers no longer have to search for them and changes are easily
implemented in quick CAM revisions.
• Eliminate errors that cause rework or scrap by verifying CNC tool paths. NC visualization is the
best technique yet. Error-free tool paths are assured and test cuts can be skipped, worry-free.
• Slash delivery times and simplify operations by minimizing machine-to-machine transfers
and setups. Job simulation addresses ways to minimize setups and transfers between machines.
Prequalified tooling, fixturing and work pieces help get rid of the need for incoming inspection—and
unpleasant surprises on the loading dock.
• Integrate inspection and quality assurance. Geometric dimensioning and tolerance (GD&T)
helps avoid potential disputes. When disputes do occur, the data is on hand in CAM to resolve
them equitably.
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• Generate accurate time estimates and avoid collisions by simulating processes.
• Get the best from skilled workers by increasing their productivity. Capturing best practices—
and enforcing their reuse—goes a long way toward stamping out process variations, which are still
the greatest source of manufacturing error.
• Evaluate workarounds for avoiding production bottlenecks and optimize key equipment. This
means delivery promises can be relied on by everyone.
PROCESS PLANNING
INTRODUCTION
Process planning translates design information into the process steps and instructions to efficiently
and effectively manufacture products. As the design process is supported by many computer-aided
tools, computer-aided process planning (CAPP) has evolved to simplify and improve process
planning and achieve more effective use of manufacturing resources.
PROCESS PLANNING
Process planning encompasses the activities and functions to prepare a detailed set of plans and
instructions to produce a part. The planning begins with engineering drawings, specifications, parts
or material lists and a forecast of demand.
The results of the planning are:
* Routings which specify operations, operation sequences, work centers, standards, tooling and
fixtures. This routing becomes a major input to the manufacturing resource planning system to
define operations for production activity control purposes and define required resources for
capacity requirements planning purposes.
* Process plans which typically provide more detailed, step-by-step work instructions including
dimensions related to individual operations, machining parameters, set-up instructions, and quality
assurance checkpoints.
* Fabrication and assembly drawings to support manufacture (as opposed to engineering
drawings to define the part).
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Manual process planning is based on a manufacturing engineer's experience and knowledge of
production facilities, equipment, their capabilities, processes, and tooling. Process planning is very
time-consuming and the results vary based on the person doing the planning.
CAPP
Manufacturers have been pursuing an evolutionary path to improve and computerize process
planning in the following five stages:
Stage I - Manual classification; standardized process plans
Stage II - Computer maintained process plans
Stage III - Variant CAPP
Stage IV - Generative CAPP
Stage V - Dynamic, generative CAPP
Prior to CAPP, manufacturers attempted to overcome the problems of manual process planning by
basic classification of parts into families and developing somewhat standardized process plans for
parts families (Stage I). When a new part was introduced, the process plan for that family would
be manually retrieved, marked-up and retyped. While this improved productivity, it did not
improve the quality of the planning of processes and it did not easily take into account the
differences between neither parts in a family nor improvements in production processes.
Computer-aided process planning initially evolved as a means to electronically store a process plan
once it was created, retrieve it, modify it for a new part and print the plan (Stage II). Other
capabilities of this stage are table-driven cost and standard estimating systems.
This initial computer-aided approach evolved into what is now known as "variant" CAPP. However,
variant CAPP is based on a Group Technology (GT) coding and classification approach to identify a
larger number of part attributes or parameters. These attributes allow the system to select a
baseline process plan for the part family and accomplish about ninety percent of the planning
work. The planner will add the remaining ten percent of the effort modifying or fine-tuning the
process plan. The baseline process plans stored in the computer are manually entered using a
super planner concept that is, developing standardized plans based on the accumulated experience
and knowledge of multiple planners and manufacturing engineers (Stage III).
The next stage of evolution is toward generative CAPP (Stage IV). At this stage, process planning
decision rules are built into the system. These decision rules will operate based on a part's group
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technology or features technology coding to produce a process plan that will require minimal
manual interaction and modification (e.g., entry of dimensions).
While CAPP systems are moving more and more towards being generative, a pure generative
system that can produce a complete process plan from part classification and other design data is
a goal of the future. This type of purely generative system (in Stage V) will involve the use of
artificial intelligence type capabilities to produce process plans as well as be fully integrated in a
CIM environment. A further step in this stage is dynamic, generative CAPP which would consider
plant and machine capacities, tooling availability, work center and equipment loads, and
equipment status (e.g., maintenance downtime) in developing process plans.
The process plan developed with a CAPP system at Stage V would vary over time depending on the
resources and workload in the factory. For example, if a primary work center for an operation(s)
was overloaded, the generative planning process would evaluate work to be released involving that
work center, alternate processes and the related routings. The decision rules would result in
process plans that would reduce the overloading on the primary work center by using an alternate
routing that would have the least cost impact. Since finite scheduling systems are still in their
infancy, this additional dimension to production scheduling is still a long way off.
Dynamic, generative CAPP also implies the need for online display of the process plan on a work
order oriented basis to insure that the appropriate process plan was provided to the floor. Tight
integration with a manufacturing resource planning system is needed to track shop floor status
and load data and assess alternate routings vis-à-vis the schedule. Finally, this stage of CAPP
would directly feed shop floor equipment controllers or, in a less automated environment, display
assembly drawings online in conjunction with process plans.
CAPP Planning Process
The system logic involved in establishing a variant process planning system is relatively straight
forward - it is one of matching a code with a pre-established process plan maintained in the
system. The initial challenge is in developing the GT classification and coding structure for the part
families and in manually developing a standard baseline process plan for each part family.
The first key to implementing a generative system is the development of decision rules appropriate
for the items to be processed. These decision rules are specified using decision trees, computer
languages involving logical "if-then" type statements, or artificial intelligence approaches with
object-oriented programming.
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A second key to generative process planning is the available data related to the part to drive the
planning. Simple forms of generative planning systems may be driven by GT codes. Group
technology or features technology (FT) type classification without a numeric code may be used to
drive CAPP. This approach would involve a user responding to a series of questions about a part
that in essence capture the same information as in a GT or FT code. Eventually when features-
oriented data is captured in a CAD system during the design process, this data can directly drive
CAPP
CAPP BENEFITS
Significant benefits can result from the implementation of CAPP. In a detailed survey of twenty-two
large and small companies using generative-type CAPP systems, the following estimated cost
savings were achieved:
* 58% reduction in process planning effort
* 10% saving in direct labor
* 4% saving in material
* 10% saving in scrap
* 12% saving in tooling
* 6% reduction in work-in-process
In addition, there are intangible benefits as follows:
* Reduced process planning and production lead-time; faster response to engineering changes
* Greater process plan consistency; access to up-to-date information in a central database
* Improved cost estimating procedures and fewer calculation errors
* More complete and detailed process plans
* Improved production scheduling and capacity utilization
* Improved ability to introduce new manufacturing technology and rapidly update process plans
to utilize the improved technology
Master Production Schedule (MPS)
A master production schedule (MPS) is a plan for production, staffing, inventory, etc., It is usually
linked to manufacturing where the plan indicates when and how much of each product will be
demanded. This plan quantifies significant processes, parts, and other resources in order to
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optimize production, to identify bottlenecks, and to anticipate needs and completed goods. Since
an MPS drives much factory activity, its accuracy and viability dramatically affect profitability.
Typical MPS's are created by software with user tweaking. Due to software limitations, but
especially the intense work required by the "master production schedulers", schedules do not
include every aspect of production, but only key elements that have proven their control
effectively, such as forecast demand, production costs, inventory costs, lead time, working hours,
capacity, inventory levels, available storage, and parts supply. The choice of what to model varies
among companies and factories.
The MPS is a statement of what the company expects to produce and purchase (ie. quantity to be
produced, staffing levels, dates, available to promise, projected balance).The MPS translates the
business plan, including forecast demand, into a production plan using planned orders in a true
multi-level optional component scheduling environment. Using MPS helps avoid shortages, costly
expediting, last minute scheduling, and inefficient allocation of resources. Working with MPS allows
businesses to consolidate planned parts, produce master schedules and forecasts for any level of
the Bill of Material (BOM) for any type of part.
Features of MPS
FEATURES
* Accepts and consolidates independent demand from Manual Forecasts, Sales Forecasts,
Customer Orders and Electronic (EDI) Customer Releases.
* Allows extensive manipulation of draft master schedules through menu features such as
rolling, netting, scrap factoring, and lot sizing.
* Provides Net Change analysis between two master production schedules.
* Prints the Master Production Schedule in 12 day, 4 week, 12 week and 12 month formats.
* Provides rough-cut capacity planning to evaluate feasibility of the Master Production
Schedule in terms of critical materials, manpower, machines and finances.
* Provides Sales Forecasting for one and five year horizons.
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* Forecasts demand using moving average, weighted moving average, and exponential
smoothing with seasonal and economic trend adjustments.
* Prints Sales Forecasts in units or dollars.
* Generates a Master Production Schedule (MPS) file for use by the MRP application.
* Maintains multiple shop calendars.
* Provides long horizons for capacity and resource planning.
* The system integrates with the Genzlinger Release/Shipment Communications, Customer
Order Processing, Material Requirement Planning and Inventory Management applications.
Capacity Planning
Capacity planning is the process of determining the production capacity needed by an organization
to meet changing demands for its products. In the context of capacity planning, "capacity" is the
maximum amount of work that an organization is capable of completing in a given period of time.
A discrepancy between the capacity of an organization and the demands of its customers results in
inefficiency, either in under-utilized resources or unfulfilled customers. The goal of capacity
planning is to minimize this discrepancy. Demand for an organization's capacity varies based on
changes in production output, such as increasing or decreasing the production quantity of an
existing product, or producing new products.
Better utilization of existing capacity can be accomplished through improvements in overall
equipment effectiveness (OEE). Capacity can be increased through introducing new techniques,
equipment and materials, increasing the number of workers or machines, increasing the number of
shifts, or acquiring additional production facilities.
Capacity is calculated: (number of machines or workers) × (number of shifts) ×
(utilization) × (efficiency).
The broad classes of capacity planning are lead strategy, lag strategy, and match strategy.
* Lead strategy is adding capacity in anticipation of an increase in demand. Lead strategy is an
aggressive strategy with the goal of luring customers away from the company's competitors. The
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possible disadvantage to this strategy is that it often results in excess inventory, which is costly
and often wasteful.
* Lag strategy refers to adding capacity only after the organization is running at full capacity or
beyond due to increase in demand (North Carolina State University, 2006). This is a more
conservative strategy. It decreases the risk of waste, but it may result in the loss of possible
customers.
* Match strategy is adding capacity in small amounts in response to changing demand in the
market. This is a more moderate strategy.
Fig (Sample Capacity Planning)
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Material Requirements Planning (MRP)
Material Requirements Planning (MRP) is a software-based production planning and inventory
control system used to manage manufacturing processes. Although it is not common nowadays, it
is possible to conduct MRP by hand as well. Material Requirements Planning (MRP) is a material
planning methodology developed in the 1970's making use of computer technology.
The main features of MRP are the creation of material requirements via exploding the bills of
material, and time-phasing of requirements using posted average lead times. MRP II was
developed as the second generation of MRP and it features the closed loop system: production
planning drives the master schedule which drives the material plan which is the input to the
capacity plan. Feedback loops provide input to the upper levels as a reiterative process.
An MRP system is intended to simultaneously meet three objectives:
* Ensure materials and products are available for production and delivery to customers.
* Maintain the lowest possible level of inventory.
* Plan manufacturing activities, delivery schedules and purchasing activities.
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Fig (MRP-Material Requirement Planning)
Manufacturing Resources Planning (MRP-II)
Manufacturing Resource Planning (MRP II) is defined by APICS as a method for the effective
planning of all resources of a manufacturing company. Ideally, it addresses operational planning in
units, financial planning in dollars, and has a simulation capability to answer "what-if" questions
and extension of closed-loop MRP.
Manufacturing Resource Planning, also known as MRPII, is based on combining Material
Requirement Planning (MRP) with Capacity Requirements Planning (CRP), with the additional
inputs from other computer systems within the organization. MRPII is designed to widen the range
of MRP to allow financial and production planning.
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APICs define Manufacturing Resource Planning (MRP II) as a method for the effective planning of
all resources of a manufacturing company. It addresses operational planning in units, financial
planning in dollars, and has a simulation capability to answer "what-if" questions and extension of
closed-loop MRP.
Purpose
It is a combination of people skills, data base accuracy, and computer resources. It integrates
many areas of the manufacturing enterprise into a single entity for planning and control purposes,
from board level to operative and from five-year plan to individual shop-floor operation. It builds
on closed-loop Material Requirements Planning (MRP) by adopting the feedback principle and also
extends it to additional areas of the enterprise, primarily manufacturing-related. It is a total
company management concept for using human resources more productively.
Building Blocks
A Business Application which manages the resources associated with a manufacturing operation.
The MRP begins with the output requirements and decomposes them into inputs and operations
sequenced across time.
Using an MRP an organization can identify the necessary raw materials and schedule
manufacturing operations within distinct timeframes in order to meet specific commitments.
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Fig (Manufacturing Resources Planning - II)
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Concept of Design for Excellence (DFX)
Definition:
Critical design reviews are provided by ICS to ensure that your products meet manufacturing
requirements, that they are conducive to testing, and that your required materials are available
and are of good quality. The ICS Design For Excellence ensures that the issues related to the
quality, cost, and manufacturing cycle time of your product are addressed early in their product
life which allows your resources to concentrate on the next generation design.
DFX Overview
Design For Excellence (DFX) is concurrent Engineering. Reviews are conducted at key points
within a predefined project plan that leverage the experience of the four key organizations within
ICS: the Materials, Manufacturing, Quality, and Test Organizations. Design For Component Cost
(DFC) reviews are performed on product material listings from the concept phase to recurring
points in the sustaining production phase. The results of the DFC reviews alert the product design
teams to the end of life availability and lead time issues along with supplier quality issues.
Design For Manufacturing (DFM) reviews are performed at the System Level, Mechanical Piece
Level and PCB Level. Issues related to Assembly, Service, Quality, and Process are documented
and delivered to the Product Design Team. Manufacturing process strategies are formulated
including plans for new technology requirements.
Design For Quality (DFQ) reviews are ongoing throughout the product life cycle. Approved
vendors are monitored for quality and delivery. Process flows and process failure mode effects
analysis (PFMEA’s) are developed. Control plans are put in place to address areas of risk exposed
by the PFMEA’s. Gauges, fixtures and tooling are reviewed for robustness along with
accountability in the quality systems and requirements. These items are combined with regular
reviews of theoretical vs. actual yield data. Results from these review processes may drive
process improvement projects.
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Design for Manufacture / Assembly (DFM/A)
A methodology and tool set used to determine how to simplify a current or future product design
and/or manufacturing process to achieve cost savings. DFMA allows for improved supply chain cost
management, product quality and manufacturing, and communication between Design,
Manufacturing, Purchasing and Management. Much of the early and significant work on DFM and
DFA was done in the early 1970s by Boothroyd and Dew Hurst. Traditionally, product development
was essentially done in several stages.
The designer(s) (who usually had very good knowledge of materials, mechanisms, etc.) would
design the product, and sometimes would construct working prototypes. Once the prototype was
tested and approved, the manufacturing team would then construct manufacturing plans for the
product, including the tooling etc. Often, different materials (e.g. different thickness or type of
sheet metal), and different components (e.g. different sized screws etc), would be substituted by
the manufacturing team. Their goal was to achieve the same functionality, but make mass
production more efficient. However, the majority of the design remained unchanged, since the
manufacturing engineers could never be sure whether a change would affect some functional
requirement.
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UNIT - III
CNC MACHINES
Numerical control
DEFINITION
Numerical control (NC) refers to the automation of machine tools that are operated by abstractly
programmed commands encoded on a storage medium, as opposed to manually controlled via
hand wheels or levers, or mechanically automated via cams alone. The first NC machines were
built in the 1940s and '50s, based on existing tools that were modified with motors that moved the
controls to follow points fed into the system on paper tape.
These early servomechanisms were rapidly augmented with analog and digital computers, creating
the modern computer numerical controlled (CNC) machine tools that have revolutionized the
design process. In modern CNC systems, end-to-end component design is highly automated using
CAD/CAM programs. The programs produce a computer file that is interpreted to extract the
commands needed to operate a particular machine, and then loaded into the CNC machines for
production.
Since any particular component might require the use of a number of different tools—drills, saws,
etc.—modern machines often combine multiple tools into a single "cell". In other cases, a number
of different machines are used with an external controller and human or robotic operators that
move the component from machine to machine. In either case, the complex series of steps needed
to produce any part is highly automated and produces a part that closely matches the original CAD
design.
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Fig (CNC Machine)
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DNC
Direct numerical control (DNC), also known as distributed numerical control (also DNC), is a
common manufacturing term for networking CNC machine tools. On some CNC machine
controllers, the available memory is too small to contain the machining program (for example
machining complex surfaces), so in this case the program is stored in a separate computer and
sent directly to the machine, one block at a time.
If the computer is connected to a number of machines it can distribute programs to different
machines as required. Usually, the manufacturer of the control provides suitable DNC software.
However, if this provision is not possible, some software companies provide DNC applications that
fulfill the purpose. DNC networking or DNC communication is always required when CAM programs
are to run on some CNC machine control.
CMM DEFINITION
A coordinate measuring machine (CMM) is a device for measuring the physical geometrical
characteristics of an object. This machine may be manually controlled by an operator or it may be
computer controlled. Measurements are defined by a probe attached to the third moving axis of
this machine. Probes may be mechanical, optical, laser, or white light, among others.
Description
The typical "bridge" CMM is composed of three axes, an X, Y and Z. These axes are orthogonal to
each other in a typical three dimensional coordinate system. Each axis has a scale system that
indicates the location of that axis. The machine will read the input from the touch probe, as
directed by the operator or programmer. The machine then uses the X,Y,Z coordinates of each of
these points to determine size and position. Typical precision of a coordinate measuring machine is
measured in Microns, or Micrometers, which is 1/1,000,000 of a meter.
A coordinate measuring machine (CMM) is also a device used in manufacturing and assembly
processes to test a part or assembly against the design intent. By precisely recording the X, Y, and
Z coordinates of the target, points are generated which can then be analyzed via regression
algorithms for the construction of features. These points are collected by using a probe that is
positioned manually by an operator or automatically via Direct Computer Control (DCC). DCC
CMMs0 can be programmed to repeatedly measure identical parts, thus a CMM is a specialized
form of industrial robot.
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Fig (Coordinate measuring machine (CMM)
Definition
CNC Definition and PPT
CNC (Computer Numerically Controlled) Machines are programmed and controlled by computer so
can offer very short set up times and the flexibility to run batches from one offs to several
thousand.
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CNC EDM Machines
[CNC EDM MACHINE]
EDM Machine
Electric discharge machining (EDM), sometimes colloquially also referred to as spark machining,
spark eroding, burning, die sinking or wire erosion, is a manufacturing process whereby a wanted
shape of an object, called work piece, is obtained using electrical discharges (sparks). The material
removal from the work piece occurs by a series of rapidly recurring current discharges between
two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the
electrodes is called tool-electrode and is sometimes simply referred to as ‘tool’ or ‘electrode’,
whereas the other is called work piece-electrode, commonly abbreviated in ‘work piece’.
When the distance between the two electrodes is reduced, the intensity of the electric field in the
volume between the electrodes is expected to become larger than the strength of the dielectric (at
least in some point(s)) and therefore the dielectric breaks allowing some current to flow between
the two electrodes. This phenomenon is the same as the breakdown of a capacitor (condenser). A
collateral effect of this passage of current is that material is removed from both the electrodes.
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Once the current flow stops (or it is stopped - depending on the type of generator), new liquid
dielectric should be conveyed into the inter-electrode volume enabling the removed electrode
material solid particles (debris) to be carried away and the insulating proprieties of the dielectric to
be restored. This addition of new liquid dielectric in the inter-electrode volume is commonly
referred to as flushing. Also, after a current flow, a difference of potential between the two
electrodes is restored as it was before the breakdown, so that a new liquid dielectric breakdown
can occur.
Fig (Electric discharge machining (EDM)
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UNIT – IV
CNC Components & Part Programming
Spindle Drive
Driver: Spindle Drive
A spindle drive is a primitive type of transmission. A rod, referred to as a spindle, is attached to
the output end of and engine. This rod then comes in direct contact with a tired.
There are several limitations to this design. The spindle-tire interface is prone to inefficiency and
slippage since the contact area is very limited. Water of any sort on the tire will render a spindle
drive unusable until it dries.
Fig (Spindle Drive Model)
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Advantages
Simplicity
The greatest advantage to a spindle driven transmission is simplicity. It is because of this
simplicity that spindle driven scooters are the generally the least expensive scooters available.
Low maintenance
Spindle drives also require no lubrication and minimal maintenance.
Disadvantages
Wear
Spindles cause excessive wear on the tire to which they are connected and require constant re-
adjustment in order to maintain an optimal pressure on a tire's surface. the black magic spindle is
an aftermarket spindle that has TONS of grip, but it also wears your tire down a lot faster than a
stock or knurled ADA spindle.
Sensitivity
stock Spindles cannot grip the tire on water. but if you have a black magic spindle you can ride on
water and you can ride on packed dirt at minimal speeds of coarse.
Pressure stress
In order to maintain an efficient contact, excessive stress must be put on the spindle, and
therefore, the engine. It is not uncommon to bend or break a crankshaft on a spindle drive. 3rd
bearing supports are sold to help remedy this problem.
Hydraulic systems
A hydraulic or hydrostatic drive system or hydraulic power transmission is a drive or transmission
system that uses hydraulic fluid under pressure to drive machinery. The term hydrostatic refers to
the transfer of energy from flow and pressure, not from the kinetic energy of the flow. Such a
system basically consists of three parts. The generator (e.g. a hydraulic pump, driven by an
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electric motor, a combustion engine or a windmill); valves, filters, piping etc. (to guide and control
the system); the motor (e.g. a hydraulic motor or hydraulic cylinder) to drive the machinery.
Principle of a hydraulic drive
Pascal's law is the basis of hydraulic drive systems. As the pressure in the system is the same, the
force that the fluid gives to the surroundings is therefore equal to pressure x area. In such a way,
a small piston feels a small force and a large piston feels a large force. The same counts for a
hydraulic pump with a small swept volume that asks for a small torque combined with a hydraulic
motor with a large swept volume that gives a large torque. In such a way a transmission with a
certain ratio can be built.
Most hydraulic drive systems make use of hydraulic cylinders. Here the same principle is used- a
small torque can be transmitted in to a large force. By throttling the fluid between generator part
and motor part, or by using hydraulic pumps and/or motors with adjustable swept volume, the
ratio of the transmission can be changed easily. In case throttling is used, the efficiency of the
transmission is limited; in case adjustable pumps and motors are used, the efficiency however is
very large.
In fact, up to around 1980, a hydraulic drive system had hardly any competition from other
adjustable (electric) drive systems. Nowadays electric drive systems using electric servo-motors
can be controlled in an excellent way and can easily compete with rotating hydraulic drive
systems. Hydraulic cylinders are in fact without competition for linear (high) forces. For these
cylinders anyway hydraulic systems will remain of interest and if such a system is available, it is
easy and logical to use this system also for the rotating drives of the cooling systems.
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Fig (Hydraulic system)
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Direct Current Motor
In the late 1800s, several inventors built the first working motors, which used direct current (DC)
power. After the invention of the induction motor, alternating current (AC) machines largely
replaced DC machines in most applications. However, DC motors still have many uses.
DC motor principles. DC motors consist of rotor-mounted windings (armature) and stationary
windings (field poles). In all DC motors, except permanent magnet motors, current must be
conducted to the armature windings by passing current through carbon brushes that slide over a
set of copper surfaces called a commentator, which is mounted on the rotor. The commentator
bars are soldered to armature coils. The brush/commentator combination makes a sliding switch
that energizes particular portions of the armature, based on the position of the rotor. This process
creates north and south magnetic poles on the rotor that are attracted to or repelled by north and
south poles on the stator, which are formed by passing direct current through the field windings.
It's this magnetic attraction and repulsion that causes the rotor to rotate.
The advantages
The greatest advantage of DC motors may be speed control. Since speed is directly proportional to
armature voltage and inversely proportional to the magnetic flux produced by the poles, adjusting
the armature voltage and/or the field current will change the rotor speed. Today, adjustable
frequency drives can provide precise speed control for AC motors, but they do so at the expense of
power quality, as the solid-state switching devices in the drives produce a rich harmonic spectrum.
The DC motor has no adverse effects on power quality.
The drawbacks
Power supply, initial cost, and maintenance requirements are the negatives associated with DC
motors.
* Rectification must be provided for any DC motors supplied from the grid. It can also cause
power quality problems.
* The construction of a DC motor is considerably more complicated and expensive than that
of an AC motor, primarily due to the commentator, brushes, and armature windings. An induction
motor requires no commentator or brushes, and most use cast squirrel-cage rotor bars instead of
true windings — two huge simplifications.
* Maintenance of the brush/commentator assembly is significant compared to that of
induction motor designs.
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In spite of the drawbacks, DC motors are in wide use, particularly in niche applications like cars
and small appliances.
A brushless DC motor (BLDC) is a synchronous electric motor which is powered by direct-current
electricity (DC) and which has an electronically controlled commutation system, instead of a
mechanical commutation system based on brushes. In such motors, current and torque, voltage
and rpm are linearly related.
A BLDC motor powering a micro remote-controlled airplane. The motor is connected to a
microprocessor-controlled BLDC controller. This 5-gram motor is approximately 11 watts (15 mill
horsepower) and produces about two times more thrust than the weight of the plane. Being an out
runner, the rotor-can containing the magnets spins around the coil windings on the stator.
Two subtypes exist:
* The stepper motor type may have more poles on the stator (fixed permanent magnet).
* The reluctance motor.
In a conventional (brushed) DC motor, the brushes make mechanical contact with a set of
electrical contacts on the rotor (called the commutator), forming an electrical circuit between the
DC electrical source and the armature coil-windings. As the armature rotates on axis, the
stationary brushes come into contact with different sections of the rotating commutator. The
commutator and brush system form a set of electrical switches, each firing in sequence, such that
electrical-power always flows through the armature coil closest to the stationary stator.
In a BLDC motor, the electromagnets do not move; instead, the permanent magnets rotate and
the armature remains static. This gets around the problem of how to transfer current to a moving
armature. In order to do this, the brush-system/commutator assembly is replaced by an electronic
controller. The controller performs the same power distribution found in a brushed DC motor, but
using a solid-state circuit rather than a commutator/brush system.
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Stepper Motor
A stepper motor (or step motor) is a brushless, synchronous electric motor that can divide a full
rotation into a large number of steps. The motor's position can be controlled precisely without any
feedback mechanism (see Open-loop controller), as long as the motor is carefully sized to the
application. Stepper motors are similar to switched reluctance motors (which are very large
stepping motors with a reduced pole count, and generally are closed-loop commutated.)
Fundamentals of Operation
Stepper motors operate differently from DC brush motors, which rotate when voltage is applied to
their terminals. Stepper motors, on the other hand, effectively have multiple "toothed"
electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are
energized by an external control circuit, such as a microcontroller. To make the motor shaft turn,
first one electromagnet is given power, which makes the gear's teeth magnetically attracted to the
electromagnet's teeth. When the gear's teeth are thus aligned to the first electromagnet, they are
slightly offset from the next electromagnet. So when the next electromagnet is turned on and the
first is turned off, the gear rotates slightly to align with the next one, and from there the process is
repeated. Each of those slight rotations is called a "step," with an integer number of steps making
a full rotation. In that way, the motor can be turned by a precise angle.
Stepper motor characteristics
1. Stepper motors are constant power devices.
2. As motor speed increases, torque decreases.
3. The torque curve may be extended by using current limiting drivers and increasing the driving
voltage.
4. Steppers exhibit more vibration than other motor types, as the discrete step tends to snap the
rotor from one position to another.
5. This vibration can become very bad at some speeds and can cause the motor to lose torque.
6. The effect can be mitigated by accelerating quickly through the problem speeds range,
physically damping the system, or using a micro-stepping driver.
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7. Motors with a greater number of phases also exhibit smoother operation than those with fewer
phases.
Fig (Stepper Motor)
Servo Motors
Servo motors are used in closed loop control systems in which work is the control variable. The
digital servo motor controller directs operation of the servo motor by sending velocity command
signals to the amplifier, which drives the servo motor. An integral feedback device (resolve) or
devices (encoder and tachometer) are either incorporated within the servo motor or are remotely
mounted, often on the load itself.
These provide the servo motor's position and velocity feedback that the controller compares to its
programmed motion profile and uses to alter its velocity signal. Servo motors feature a motion
profile, which is a set of instructions programmed into the controller that defines the servo motor
operation in terms of time, position, and velocity. The ability of the servo motor to adjust to
differences between the motion profile and feedback signals depends greatly upon the type of
controls and servo motors used.
See the servo motors Control and Sensors Product section. Three basic types of servo motors are
used in modern servo systems: ac servo motors, based on induction motor designs; dc servo
motors, based on dc motor designs; and ac brushless servo motors, based on synchronous motor
designs. Servo motors are special category of motors, designed for applications involving position
control, velocity control and torque control.
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Fig (Servo Motor Sensor)
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Fig (Servo Motors)
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Fig (Servo Diagram)
These motors are special in the following ways:
1. Lower mechanical time constant.
2. Lower electrical time constant.
3. Permanent magnet of high flux density to generate the field.
4. Fail-safe electro-mechanical brakes.
CNC Programming
NC part programming:
NC part programming consists of planning and documenting the sequence of processing steps to
be performed on an NC machine. The documentation portion of part programming involves the
input medium used to transmit the program of instructions to the NC machine control unit. Part
programming can be accomplished using a variety of procedures ranging from highly manual to
highly automated methods.
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The methods are:
(1) manual part programming
(2) computer-assisted part programming
(3) part programming using CAD/CAM
(4) manual data input
CNC COMPONENTS
Fig (CNC Component)
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UNIT - V
Concept of GT Family
Group Technology or GT is a manufacturing philosophy in which the parts having similarities
(Geometry, manufacturing process and/or function) are grouped together to achieve higher level
of integration between the design and manufacturing functions of a firm.The aim is to reduce
work-in-progress and improve delivery performance by reducing lead times. GT is based on a
general principle that many problems are similar and by grouping similar problems, a single
solution can be found to a set of problems, thus saving time and effort.
The group of similar parts is known as part family and the group of machineries used to process an
individual part family is known as machine cell. It is not necessary for each part of a part family to
be processed by every machine of corresponding machine cell. This type of manufacturing in which
a part family is produced by a machine cell is known as cellular manufacturing. The manufacturing
efficiencies are generally increased by employing GT because the required operations may be
confined to only a small cell and thus avoiding the need for transportation of in-process parts.
\
Fig (Group Technology)
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FMS
Introduction to FMS – types of manufacturing - FMS components – FMS layouts – types of FMS :
flexible manufacturing cell – flexible turning cell – flexible transfer line – flexible machine systems
– benefits of FMS.
Introduction to FMS
Flexible Manufacturing system integrates many of the concepts and technologies. These concepts
and technologies include;
1. Flexible automation
2. Group technology
3. CNC Tools
4. Automated Materials handling between machines
5. Computer control of machine and Material handling
A flexible manufacturing system consists of a group of processing stations, inter connected by
means of an automated material handling and storage system and controlled by an integrated
computer system. What gives the FMS its name is that it is capable of processing a variety of
different types of parts simultaneously under NC program control at the various workstations.
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CIM
Concept of CIM
The Common Information Model (CIM) is a standard of the Distributed Management Task Force
(DMTF) and is based on the object-oriented modeling approach. This standard provides a neutral
implementation schema to describe management information within a computing environment.
Object-oriented modeling is a means of representing the real world. CIM is designed to model
hardware and software elements.
AGV
Automatic Storage and Retrieval Systems (ASRS)
An automated storage and retrieval system (ASRS or AS/RS) consists of a variety of computer-
controlled methods for automatically placing and retrieving loads from specific storage locations.
ASRSs are categorized into three main types: single masted, double masted, and man-aboard.
Most are supported on a track and ceiling guided at the top by guide rails or channels to ensure
accurate vertical alignment, although some are suspended from the ceiling.
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The 'shuttles' that make up the system travel between fixed storage shelves to deposit or retrieve
a requested load (ranging from a single book in a library system to a several ton pallet of goods in
a warehouse system). As well as moving along the ground, the shuttles are able to telescope up to
the necessary height to reach the load, and can store or retrieve loads that are several positions
deep in the shelving.
To provide a method for accomplishing throughput to and from the ASRS and the supporting
transportation system, stations are provided to precisely position inbound and outbound loads for
pickup and delivery by the crane. A man-aboard AS/RS offers significant florspace savings. This is
due to the fact that the storage system heights are no longer limited by the reach height of the
order picker.
Shelves or storage cabinets can be stacked as high as floor loading, weight capacity, throughput
requirements, and/or ceiling heights will permit. Man-aboard automated storage and retrieval
systems are far and away the most expensive picker-to-stock equipment alternative. Aisle-captive
storage/retrieval machines reaching heights up to 40 feet cost around $125,000. Hence, there
must be enough storage density and/or productivity improvement over cart and tote picking to
justify the investment.
Also, because vertical travel is slow compared to horizontal travel, typical picking rates in man-
aboard operations range between 40 and 250 lines per person-hour. The range is large because
there is a wide variety of operating schemes for man-aboard systems. Man-aboard systems are
typically appropriate for slow-moving items where space is fairly expensive.
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Fig (Automatic Storage and Retrieval Systems (ASRS))
Robotics
Definition – robot anatomy and classifications – robot configurations – industrial applications:
characteristics, material transfer, machine loading, welding, spray coating, assembly and
inspection.
Definition of Robot
A robot is a virtual or mechanical artificial agent. In practice, it is usually an electro-mechanical
system which, by its appearance or movements, conveys a sense that it has intent or agency of its
own. The word robot can refer to both physical robots and virtual software agents, but the latter
are usually referred to as bots. There is no consensus on which machines qualify as robots, but
there is general agreement among experts and the public that robots tend to do some or all of the
following: move around, operate a mechanical limb, sense and manipulate their environment, and
exhibit intelligent behavior, especially behavior which mimics humans or other animals.
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Robot Configurations
Robot configuration design is hampered by the lack of established, well-known design rules, and
designers cannot easily grasp the space of possible designs and the impact of all design variables
on a robot's performance. Realistically, a human can only design and evaluate several candidate
configurations, though there may be thousands of competitive designs that should be investigated.
In contrast, an automated approach to configuration synthesis can create tens of thousands of
designs and measure the performance of each one without relying on previous experience or
design rules.
This thesis creates Darwin2K, an extensible, automated system for robot configuration synthesis.
This research focuses on the development of synthesis capabilities required for many robot design
problems: a flexible and effective synthesis algorithm, useful simulation capabilities, appropriate
representation of robots and their properties, and the ability to accomodate application-specific
synthesis needs. Darwin2K can synthesize and optimize kinematics, dynamics, structural
geometry, actuator selection, and task and control parameters for a wide range of robots.
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Robot Configuration figures:
Fig (Robot Configuration)
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Robot anatomy
The body or the structure of a robot is related to its design purpose. For example, industrial robots
often take the shape of an arm - commonly know as Robotics Arm. This is because many tasks
require to perform in the industrial requires the flexibility of human hands and it usually remains
stationary relative to its task.
Space robots, on the other hand, have many different body shapes such as a sphere, a platform
with wheels or legs and so on. One typical example is the free-flying rover, Sprint Aercam,
designed as a sphere to minimize damage if it were to bump into the shuttle or an astronaut.
When robot needs mobility to perform its tasks, the robot's body takes in many forms depending
on the environment it operate in. For under water operation, conventional unmanned, submersible
robot, alias, Automated Underwater Vehicle is used. To get around, AUV use propellers and
rudders to control their direction of travel. Whereas, for land traveling, robot moves around with
legs, tracks or wheels. Mars Exploration Rover is one example. Not surprisingly, robots that
operate in the air use engines and thrusters to get around. One example is the Cassini, an orbiter
on its way to Saturn.
ROBOT ANATOMY:
1. Robot
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2. Robot Sensor
3. Robot Communication
4. Robot Power
5. Robot Brain
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