1 cam intro

Introduction to CAM
 Definition of CAM
 Product Cycle & CAD/CAM
 Latest trend of market
 Automation & Types of Productions
 Advantages of CAM
 CNC/NC = Flexible/Programmable
Automation
eg. Development of lathe to CNC Turning Center

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Definition of CAM
 Effective utilization of computer technology
in the MANAGEMENT, CONTROL and
OPERATIONS of the manufacturing facility
through either direct or indirect computer
interface with the physical and human
resources of the company.

 Use of computer systems to plan, manage &
control the operations of a manufacturing
plant with the plant’s production resources.

Product Cycle & CAD/CAM
Modern Product Cycle:

CAD CAM

Marketing
&
Customer
Feed back
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Traditional Manufacturing:

Process Planning (process?, m/c?)
Tooling & Equip. + Prodn Scheduling
Production
Quality Control

4

Computer Aided Manufacturing:

CAPP
MRP + CAS
Production (Robots & CNC)
CAQC

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Latest Trend of Market
Large varieties & lower product lives requires:
 Reduction in inventory, Lower cost of product
 Reduce waste, Improve quality
 Increase flexibility in manufacturing to achieve
immediate & rapid response to:
 Product changes
 Production changes
 Process changes
 Equipment changes &
 Change in personnel
“Automations & CAM/CIM meet above challenges
in manufacturing.”
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Automation & Types of Productions
 Automation: Technology concerned with the
application of complex mechanical, electronics &
computer based systems in the operation & control
of production.
 To reduce various time elements in product cycle.
Types of Production:
1. Continuous Flow
2. Mass Production
3. Batch Production
4. Job Shop
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1) Continuous Flow
 Common in food & chemical processing
industry, oil refinery, drugs and
pharmaceutical unit, etc.
 Production does not stop & the flow of
output is continuous.
 Generally, online control and continuous
system monitoring may be needed.
 All such controls are generally automated
and computer controlled. (eg. Transfer lines)
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1) Continuous Flow
 High Productivity but less Flexibility

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2) Mass Production
 Suited for the manufacturing of continuous
identical parts.
 Production lot size is very high &
production rate is continuous
 Product variety is very low, which may be
one of its kind (e.g. Automobile parts)
 i.e. Fixed Automation (Machines with
Robots & M.H.E)
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3) Batch Production
 Production lot size is medium (100 – 1000)
 Product variety is medium e.g. bolts, books...
 i.e. Flexible or Programmable Automation
(CNC with jigs & fixtures)

4) Job Shop :
 Lot size is generally small
 Production variety is generally very high
 Production equipments are mostly general
purpose and flexible
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Advantages of CAM
 Increase productivity by carrying maximum
operations in one setup.
 Flexibility in design change
 Operating flexibility
 Shorter lead time
 Increased reliability (accuracy & precession)
 Reduced maintenance & rework
 Better management control
 High speed machining
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Flexible/Prog. Automation
 System works automatically but on
instructions which can be changed as
desired.
 Conventional automatic equipments
works automatically on prog. – a
physical one in the form of “cams” i.e.
Fixed programming.
 Flexible programming == NC/CNC m/c’s

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Numeric Control (NC)
 Definition:
The control of operation of machine tools by a
series of coded instructions called the
program, which consists mainly of
alphanumeric characters (numbers and
letters).
 Characteristic: Preplanned and Predictable
 NC is a typical form of Programmable
Automation..
 1948 – U.S Air force, 1952 – NC milling (MIT)
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HISTORICAL
•DEVELOPMENT
15th century - machining metal.
• 18th century - industrialization, production-type machine tools.
• 20th century - F.W. Taylor - tool metal - HSS
Automated production equipment -
Screw machines
Transfer lines
Assembly lines
...
using cams and preset stops
Programmable automation -
NC
PLC
Robots PROBLEM IDENTIFICATION

Automated functions in NC
 Starting & stopping of m/c tool spindle
 Controlling the spindle speed
 Positioning the tool tip at desired location
 Guiding the tool along desired path
 Controlling Feed Rate
 Changing of tools in the spindle
 Changing the pallets
 Controlling coolant flow

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Suitability of NC
For following characteristic of job:
 The components have complex shape
 The parts are to be made in small batches
 Set-ups are numerous & costly
 Repeatability & accuracy is desired
 The parts are subjected to design changes
 The inspection cost is significantly more
 Expensive part & much metal to be removed
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Advantages of NC technology
 Accommodates simple to complex parts
geometry
 Increased productivity
Reduced no. of setups & its time
Reduce w/p handling & tool changing time
 Reduced inventory
 Better machine utilization
 Ensures accuracy & repeatability of work
 Flexibility in manufacturing (design change)
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Limitations of NC technology
 High Establishment & Running cost
 High maintenance cost
 Downtime of NC system is expensive
 Skill personnel for hardware & software
 Requires conditional environment

Applications of NC:
NC milling, drilling, boring, lathes, grinders,
punches& presses, welding, inspection m/c,
hobbing …..
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Operation of NC/CNC m/c tool

Part MCU Signal M/C Machined
(CPU+ to Tool Part
PLC) motors

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Components of NC/CNC system

A. Part program
B. Program i/p
device
C. MCU
D. Drive System
E. Machine Tool
F. Feed Back System

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NC SYSTEM ELEMENTS

DPU: Data Processing Unit
CLU: Control Loop Unit

Components of NC system…
A. Part program
 A series of coded instructions required to
produce a part.
 It controls the movement of the m/c tool and
on/off control of auxiliary functions.
 The program are alphanumeric. (NC block)
 Program can be written in Higher Level
Language eg. APT, UNIAPT… = CAPP
 CAPP is converted into std. part program
with the help of processors.
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B. Program i/p device
The means for part program to be entered
into the NC control. They are:
 Punch Tape Reader (EIA & ISO code tape),
 Manual Data I/P (keyboard on MCU),
 Magnetic Tape Reader,
 Floppy Disc & Computer Disc drive,
 Computer via RS-232-C communication.

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C. MCU: Machine control unit is the heart of a NC
system. It perform the following functions:
 To read & decode the coded instructions. (interpreted)
 To implement interpolations (linear, circular, &
helical) to generate axis motion commands.
 To feed the axis motion commands to the amplifier
circuits for driving the axis mechanisms.
 To receive the feedback signals of position and
speed for each drive axis.
 To implement auxiliary control functions such as
coolant or spindle on/off and tool change.
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MCU…
 Consists of electronics & hardware that read
& interpret the part program & convert into
mech. actions of m/c tool.
Elements:
 Tape reader (electro-mechanical device)
 Data buffer (store instructions into logical blocks)
 Signal o/p channels to m/c (motors & other control)
 Feedback channels (to make certainty of instruction)
 Sequence controller (to coordinate overall operation)
 Control panels (MDI, Inspection…)
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D. Drive System
It consists of amplifier circuits, drive motors, and
ball lead-screws. The MCU feeds the control
signals (position and speed) of each axis to the
amplifier circuits. The control signals are
augmented to actuate drive motors which in turn
rotate the ball lead-screws to position the machine
table.
E. Machine Tool
NC controls are used to control various types of
m/c tools. M/c tool has a slide table and a spindle to
control of position and speed.
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F. Feed Back System
 The feedback system is also referred to as
the measuring system.
 It uses position and speed transducers to
continuously monitor the position at which
the cutting tool is located at any particular
instant.
 The MCU uses the difference between
reference signals and feedback signals to
generate the control signals for correcting
position and speed errors.
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NC MACHINE
RATING
 Accuracy
 Repeatability
 Spindle and axis motor horsepower
 Number of controlled axes
 Dimension of workspace
 Features of the machine and the
controller
PROBLEM IDENTIFICATION

NC ACCURACY AND
REPEATABILITY
 Accuracy = control instrumentation
resolution and hardware accuracy.
 Control resolution: the minimum length
distinguishable by the control unit (BLU).
 Hardware inaccuracies are caused by
physical machine errors.

PROBLEM IDENTIFICATION

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