CADCAM

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SUB CODE: 12062

COMPUTER AIDED DESIGN AND MANUFACTURING

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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 –




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.




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




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




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.




(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




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,




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.




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.




• 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).




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




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.




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




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.




* 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




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)




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.




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.




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.




Fig (Manufacturing Resources Planning - II)




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.




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.




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.




Fig (CNC Machine)




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.




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.




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.




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)




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)




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




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.




Fig (Hydraulic system)




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.




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.




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.




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.




Fig (Servo Motor Sensor)




Fig (Servo Motors)




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.




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)




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)




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.




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.




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.




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.




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.




Robot Configuration figures:

Fig (Robot Configuration)




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




2. Robot Sensor

3. Robot Communication

4. Robot Power

5. Robot Brain

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