CAD/CAM/CIM (18ME72) Module -4 Part-A

COMPUTER AIDED DESIGN AND MANUFACTURING
Course Code 18ME72 CIE Marks 40
Teaching Hours / Week (L:T:P) 3:0:0 SEE Marks 60
Credits 03 Exam Hours 03
[AS PER CHOICE BASED CREDIT SYSTEM (CBCS) SCHEME]
SEMESTER – VII
Dr. Mohammed Imran
B. E. IN MECHANICAL ENGINEERING

Course Objectives
 To impart knowledge of CIM and Automation and different concepts
of automation by developing mathematical models.
 To make students to understand the Computer Applications in Design
and Manufacturing [CAD / CAM) leading to Computer integrated
systems. Enable them to perform various transformations of entities
on display devices.
To expose students to automated flow lines, assembly lines, Line
 To expose students to automated flow lines, assembly lines, Line
Balancing Techniques, and Flexible Manufacturing Systems.
 To expose students to computer aided process planning, material
requirement planning, capacity planning etc.
 To expose the students to CNC Machine Tools, CNC part
programming, and industrial robots.
 To introduce the students to concepts of Additive Manufacturing,
Internet of Things, and Industry 4.0 leading to Smart Factory.
Dr. Mohammed Imran

Course outcomes
On completion of the course the student will be able to
 CO1: Define Automation, CIM, CAD, CAM and explain the differences
between these concepts. Solve simple problems of transformations of
entities on computer screen
 CO2: Explain the basics of automated manufacturing industries
through mathematical models and analyze different types of
automated flow lines.
through mathematical models and analyze different types of
automated flow lines.
 CO3: Analyse the automated flow lines to reduce time and enhance
productivity.
 CO4: Explain the use of different computer applications in
manufacturing, and able to prepare part programs for simple jobs on
CNC machine tools and robot programming.
 CO5: Visualize and appreciate the modern trends in Manufacturing
like additive manufacturing, Industry 4.0 and applications of Internet
of Things leading to Smart Manufacturing.
Dr. Mohammed Imran

Module-4
 Computer Numerical Control: Introduction, components of
CNC, CNC programming, manual part programming, G Codes,
M Codes, programming of simple components in turning,
drilling and milling systems, programming with canned cycles.
Cutter radius compensations.
Cutter radius compensations.
 Robot Technology: Robot anatomy, joints and links, common
robot configurations, robot control systems, accuracy and
repeatability, end effectors, sensors in robotics.
 Robot programming methods: on-line and offline methods.
Robot industrial applications: material handling, processing
and assembly and inspection.
10 Hours
Dr. Mohammed Imran

Text Books:
 Automation, Production Systems
and Computer-Integrated
Manufacturing, Mikell P Groover,
4 th Edition,2015.
 CAD / CAM Principles and
Applications, P N Rao, 3 rd
Dr. Mohammed Imran
Applications, P N Rao, 3 rd
edition.
 CAD/CAM/CIM, Dr. P.
Radhakrishnan, 3 rd edition.
 Internet of Things (IoT): Digitize
or Die: Transform your
organization. Embrace the digital
evolution. Rise above the
competition, Nicolas
Windpassinger, Amazon Dr. Mohammed Imran

Reference Books:
Dr. Mohammed Imran

Chapter-8Computer Numerical Control
 Introduction,
 Components of CNC,
 CNC programming,
 Manual part programming,
 Manual part programming,
 G Codes, M Codes,
 Programming of simple components in turning,
drilling and milling systems,
 Programming with canned cycles.
 Cutter radius compensations.
Dr. Mohammed Imran

1. Introduction to CNC
Numerical control (NC) part programming involves the process of writing the
set of instructions to be followed to perform the sequence of operations on the
machine.
In this numerical control machine the part programs were transferred to input
medium like punched tape, magnetic tape etc. the tape was then read by a
machine control unit (MUC), and sent the control instruction to the NC machine.
In above definition gives that programming of NC machine as that of same
In above definition gives that programming of NC machine as that of same
programming to CNC machine except in addition to that the program is
downloaded to a computer, from where the machine control unit ( MCU) read
the program & send suitable control commands to the NC machine. Hence, the
name called Computer Numerical Control (CNC).
There are two types of part programming:
a. Manual part programming
b. Computer Assisted part programming.
Dr. Mohammed Imran

2. Components of CNC
2.1 Basic Components of an NC System
 An NC system consists of three basic components:
(1) a part program of instructions, (2) a machine
control unit, and (3) processing equipment. The
general relationship among the three components is
illustrated in Figure 1.
illustrated in Figure 1.
Figure .1 Basic components of an NC system
Cont…………
Dr. Mohammed Imran

 The part program is the set of detailed step-by-step commands that direct
the actions of the processing equipment. In machine tool applications, the
person who prepares the program is called a part programmer.
 In these applications, the individual commands refer to positions of a cutting
tool relative to the worktable on which the work part is fixtured.
 Additional instructions are usually included, such as spindle speed, feed
rate, cutting tool selection, and other functions.
Cont…………
rate, cutting tool selection, and other functions.
 The program is coded on a suitable medium for submission to the machine
control unit.
 For many years, the common medium was wide punched tape, using a
standard format that could be interpreted by the machine control unit.
 Today, punched tape has largely been replaced by newer storage
technologies in modern machine shops.
 These technologies include magnetic tape, diskettes, and electronic transfer
of part programs from a computer.
Dr. Mohammed Imran

 In modern NC technology, the machine control unit (MCU) is a
microcomputer and related control hardware that stores the
program of instructions and executes it by converting each command
into mechanical actions of the processing equipment, one command
at a time.
 The related hardware of the MCU includes components to interface
with the processing equipment and feedback control elements.
Cont…………
with the processing equipment and feedback control elements.
 The MCU also includes one or more reading devices for entering
part programs into memory.
 Software residing in the MCU includes control system software,
calculation algorithms, and translation software to convert the NC
part program into a usable format for the MCU.
 Because the MCU is a computer, the term computer numerical control
(CNC) is used to distinguish this type of NC from its technological
ancestors that were based entirely on hardwired electronics.
Dr. Mohammed Imran

2.2 Basic Components of an CNC System
 Numerical control is described as a technique to control various functions of a machine tool with an
Figure .2 Basic components of an CNC system
 Numerical control is described as a technique to control various functions of a machine tool with an
input. CNC is a microprocessor-based system, the heart and brain of a CNC machine. Following are
some of the components of a CNC system:
 Central processing unit (CPU)
 Input devices
 Machine control panel
 Programmable logic controller (PLC)
 Servo-control unit
 Display unit
 A serial communication port is often utilized to transfer data from a computer to a CNC machine.
There are international standards established for serial communications.
 The CPU is where a CNC system is controlled. It receives the data stored in the memory as part
program. The data is then decoded and modified into position control and velocity control signals. It
oversees the movement of the spindle or control axis. An action is rectified if it does not match with the
programmed data. Speed control unit works in a harmonious way with the CPU for the movement of
the machine axes.
Cont…………
Dr. Mohammed Imran

2.3 Industrial applications of CNC
CNC systems can be applied to a broad range of
industrial applications. Following are some of the
industries where CNC machining is used:
 Metal fabrication
Metal fabrication
 Electrical discharge machining
 Automotive
 Manufacturing
 Electronics
 Agriculture
Dr. Mohammed Imran

2.4 Advantages of CNC machining
The manufacturing industry relies heavily on CNC
machining. Following are some of the advantages of CNC
machining:
 Higher flexibility and repeatability
 Reduced indirect costs
Increased productivity
 Increased productivity
 Consistent quantity
 Reliable operation
 Reduced non-productive time
 Higher accuracy
 Reduced lead time
 Automatic material handling
Dr. Mohammed Imran

2.5 Disadvantages of CNC machining
 Higher investment cost.
 Higher maintenance effort.
 Part programming.
 Higher utilization of NC equipment.
Dr. Mohammed Imran

2.6 CNC Coordinate Systems
 To program the CNC processing equipment, a part programmer must define
a standard axis system by which the position of the work head relative to
the work part can be specified.
 There are two axis systems used in CNC, one for flat and prismatic work
parts and the other for rotational parts.
 Both systems are based on the Cartesian coordinates.
 The axis system for flat and block-like parts consists of the three linear axes
(x, y, z) in the Cartesian coordinate system, plus three rotational axes (a, b,
(x, y, z) in the Cartesian coordinate system, plus three rotational axes (a, b,
c), as shown in Figure 3(a).
 In most machine tool applications, the x- and y-axes are used to move and
position the worktable to which the part is attached, and the z-axis is used
to control the vertical position of the cutting tool.
 Although the workpiece rotates, this is not one of the controlled axes on most
turning machines. Consequently, the y-axis is not used. The path of the cutting
tool relative to the rotating workpiece is defined in the x–z plane, where the
x-axis is the radial location of the tool and the z-axis is parallel to the axis
of rotation of the part.
 Origin positioning
The part programmer must decide where the origin of the coordinate axis
system should be located. This decision is usually based on programming
convenience.
Figure .3 Coordinate systems used in NC (a) for
flat and prismatic work and (b) for rotational
work. (On most turning machines, the z-axis is
horizontal rather than vertical as shown here.)
Dr. Mohammed Imran

2.6 CNC Coordinate Systems
Motion Control systems
 Some NC processes are performed at discrete locations on the work part (e.g., drilling
and spot welding). Others are carried out while the work head is moving (e.g., turning,
milling, and continuous arc welding).
 If the work head is moving, it may be necessary to follow a straight line path or a circular
or other curvilinear path.
 These different types of movement are accomplished by the motion control system, whose
features are explained below.
 Point-to-point versus Continuous path Control. Motion control systems for NC can be
divided into two types: (1) point-to-point and (2) continuous path.
Cont………
divided into two types: (1) point-to-point and (2) continuous path.
 Point-to-point systems, also called positioning systems, move the worktable to a
programmed location without regard for the path taken to get to that location. Once the
move has been completed, some processing action is accomplished by the work head at
the location, such as drilling or punching a hole. Thus, the program consists of a series of
point locations at which operations are performed, as depicted in Figure 3.1.
 Continuous path systems are capable of continuous simultaneous control of two or more
axes. This provides control of the tool trajectory relative to the work part. In this case, the
tool performs the process while the worktable is moving, thus enabling the system to
generate angular surfaces, two-dimensional curves, or three-dimensional contours in the
work part. This control mode is required in many milling and turning operations. A simple
two-dimensional profile milling operation is shown in Figure 3.2 to illustrate continuous
path control. When continuous path control is utilized to move the tool parallel to only one
of the major axes of the machine tool worktable, this is called straight-cut NC. When
continuous path control is used for simultaneous control of two or more axes in machining
operations, the term contouring is used.
Dr. Mohammed Imran

3. CNC programming
 If the complex-shaped component requires calculations to
produce the component are done by the programming
software contained in the computer.
 The programmer communicates with this system through
the system language, which is based on words.
 There are various programming languages developed
in the recent past, such as APT (Automatically
 There are various programming languages developed
in the recent past, such as APT (Automatically
Programmed Tools), Mastercam, CNC-Train, EdgeCam,
ADAPT, AUTOSPOT, COMPAT-II, 2CL, ROMANCE, SPLIT is
used for writing a computer programme, which has
English like statements.
 A translator known as compiler program is used to
translate it in a form acceptable to MCU.
 The programmer has to do only following things:
(a) Define the work part geometry.
(b) Defining the repetition work.
(c) Specifying the operation sequence.
Figure.4: Interactive Graphic System in
Computer Aided Part Programme
Dr. Mohammed Imran

3. CNC programming
STEPS IN PART PROGRAMMING:
With the help of latest CAD/CAM facilities, the coding is generated
automatically from the CAD model database. This is in turn fed to the
machine control unit (MCU) and the part is machined. The important steps
involved in the development of a part program are as follows:
1. Process planning
2. Axes selection
Cont……
2. Axes selection
3. Tool selection
4. Selection of cutting parameters
5. Job and tool setup
6. Part programming
7. Program verification and feed back
8. Machining process
Each of these steps is important, and this is interlinked. NC machine cannot
function unless all the above steps are followed in the sequence.
Dr. Mohammed Imran

3.1 Manual part programming
The programmer first prepares the program manuscript in a standard
format. Manuscripts are typed with a device known as flexo-writer,
which is also used to type the program instructions. After the program is
typed, the punched tape is prepared on the flexo writer. Complex
shaped components require tedious calculations. This type of
programming is carried out for simple machining parts produced on
point-to-point machine tool.
Cont……
point-to-point machine tool.
 To be able to create a part program manually, need the
following information:
 Knowledge about various manufacturing processes and
machines.
 Sequence of operations to be performed for a given
component.
 Knowledge of the selection of cutting parameters.
 Editing the part program according to the design changes.
 Knowledge about the codes and functions used in part programs
Dr. Mohammed Imran

3.1.1 Programming Fundamentals
A program defining motion of tool / workpiece in this coordinate
system is known as a part program. Lathe and Milling machines
are taken for case study but other machine tools like CNC
grinding, CNC hobbing, CNC filament winding machine, etc. can
also be dealt with in the same manner.
1. Reference Point
Part programming requires establishment of some reference
points. Three reference points are either set by manufacturer or
user.
a) Machine Origin
Cont……
a) Machine Origin
b) Program Origin
c) Part Origin
2. Axis Designation
 For typical lathe machine degree of freedom is 2 and so it called
2 axis machines.
 For typical lathe machine degree of freedom is 3 and so it called
2 axis machines.
3. Setting up of Origin
 In case of CNC machine tool rotation of the reference axis is not
possible.
 Origin can set by selecting three reference planes X, Y and Z.
 Planes can be set by touching tool on the surfaces of the
workpiece and setting that surfaces as X=x, Y=y and Z=z.
Dr. Mohammed Imran

3.2 G Codes, M Codes
3.2.1 Coding Systems
 The programmer and the operator must use a coding
system to represent information, which the controller
can interpret and execute.
 A frequently used coding system is the Binary-Coded
 A frequently used coding system is the Binary-Coded
Decimal or BCD system.
 This system is also known as the EIA Code set because
it was developed by Electronics Industries
Association.
 The newer coding system is ASCII and it has become the
ISO code set because of its wide acceptance.
Dr. Mohammed Imran

COMMONLY USED WORD ADDRESSES
 N-CODE: Sequence number, used to identify each block with in an NC program and
provides a means by which NC commands may be rapidly located. It is program line
number. It is a good practice to increment each block number by 5 to 10 to allow
additional blocks to be inserted if future changes are required.
 G-CODE: Preparatory Word, used as a communication device to prepare the MCU. The
G-code indicates that a given control function such as G01, linear interpolation, is to be
requested.
requested.
 X, Y & Z-CODES: Coordinates. These give the coordinate positions of the tool
 F-CODE: Feed rate. The F code specifies the feed in the machining operation.
 S-CODE: Spindle speed. The S code specifies the cutting speed of the machining process.
 T-CODE: Tool selection. The T code specifies which tool is to be used in a specific
operation.
 M-CODE: Miscellaneous function. The M code is used to designate a particular mode of
operation for an NC machine tool.
 I, J & K-CODES: They specify the centre of arc coordinates from starting.
Dr. Mohammed Imran

3.2.2 CNC Code Syntax
The CNC machine uses a set of rules to enter, edit,
receive and output data. These rules are known as
CNC Syntax, Programming format, or tape format.
Cont……
CNC Syntax, Programming format, or tape format.
Dr. Mohammed Imran

3.2.3 Types of CNC codes
3.2.3.1 Preparatory codes (G-Codes)
 The term "preparatory" in NC means that it "prepares" the
control system to be ready for implementing the information
that follows in the next block of instructions.
A preparatory function is designated in a program by the
Cont……
 A preparatory function is designated in a program by the
word address G followed by two digits.
 Preparatory functions are also called G-codes and they specify
the control mode of the operation.
 On some older controllers, cutter positioning (axis) commands
(e.g., G00, G01, G02, G03, & G04) are non-modal requiring
a new positioning command to be entered each time the cutter
(or axis) is moved to another location
Dr. Mohammed Imran

Cont……
MILLING POSITIONING COMMAND
CODS AND ITS FUNCTIONS
TURNING POSITIONING COMMAND
CODS AND ITS FUNCTIONS
Dr. Mohammed Imran

Cont……
Dr. Mohammed Imran

3.2.3 Types of CNC codes
3.2.3.2 Miscellaneous codes (M-Codes)
 Miscellaneous functions use the address letter M followed by two digits.
They perform a group of instructions such as coolant on/off, spindle
on/off, tool change, program stop, or program end.
 They are often referred to as machine functions or M-functions. Some
of the M codes are given below
Cont……
They are often referred to as machine functions or M-functions. Some
of the M codes are given below
Dr. Mohammed Imran

Concepts Programming
 Programming modes
Programming mode should be specified when it needs to
be changed from absolute to incremental and vice versa.
There are two programming modes, absolute and incremental
and is discussed below.
 Absolute programming (G90)
In absolute programming, all measurements are made from the part
origin established by the programmer and set up by the operator. Any
programmed coordinate has the absolute value in respect to the absolute
Figure .7 Absolute
distance
origin established by the programmer and set up by the operator. Any
programmed coordinate has the absolute value in respect to the absolute
coordinate system zero point. The machine control uses the part origin as
the reference point in order to position the tool during program execution
(Figure 7).
 Relative programming (G91)
In incremental programming, the tool movement is measured from the last
tool position. The programmed movement is based on the change in
position between two successive points. The coordinate value is always
incremented according to the preceding tool location. The
programmer enters the relative distance between current location and
the next point (Figure 8).
 Spindle control
The spindle speed is programmed by the letter 'S' followed by four digit
number, such as S1000. There are two ways to define speed:
1. Revolutions per minute (RPM)
2. Constant surface speed
distance
measured from the
reference zero
Figure .8
incremental
distances measured
from the previous
location
Dr. Mohammed Imran

G00 Rapid traverse
When the tool being positioned at a point preparatory to a cutting motion,
to save time it is moved along a straight line at Rapid traverse, at a fixed
traverse rate which is pre-programmed into the machine's control system.
Typical rapid traverse rates are 10 to 25 m /min., but can be as high as
80 m/min.
Syntax: N010 [G90/G91] G00 X10 Y10 Z5
Dr. Mohammed Imran

Dr. Mohammed Imran

 Tool selection
Tool selection is accomplished using 'T' function followed by a four digit number where, first two digits are used to call the particular tool and
last two digits are used to represent tool offset in the program.
EX : T01 12
 Feed rate control
Cutting operations may be programmed using two basic feed rate modes:
1. Feed rate per spindle revolution
2. Feed rate per time
2. Feed rate per time
The feed rate per spindle revolution depends on the RPM programmed.
 Subroutines (M98)
Any frequently programmed order of instruction or unchanging sequences can benefit by becoming a subprogram. Typical applications for
subprogram applications in CNC programming are:
Repetitive machining motions, Functions relating to tool change, Hole patterns, Grooves and threads, Machine warm-up routines, Pallet
changing & Special functions and others
Structurally, subprograms are similar to standard programs. They use the same syntax rules. The benefits of subroutines involve the reduction in
length of program, and reduction in program errors
 Canned Cycles
A canned cycle is a preprogrammed sequence of events / motions of tool / spindle stored in memory of controller. Every canned cycle has a
format. Canned cycle is modal in nature and remains activated until cancelled. Canned cycles are a great resource to make manual
programming easier. Often underutilized, canned cycles save time and effort.
Dr. Mohammed Imran

Machining a Rectangular pocket
G172 I J K P Q R X Y Z
G173 I K P T S R F B J Z
G172
I-pocket total x-length
J-pocket total y-length
K-radius of corner roundness
P-zero for rough cycle allowance (smooth
<0.5) Q-cut increment along z-axis (5pecks
5mm)
R-absolute reference point for z
X-absolute datum or reference position x-
axis Y- Absolute datum or reference position
y-axis Z-depth of cut
G173
I-pocket side finishing allowance (0-0.5)
K-pocket base finish allowance (0-0.5) P-cut
with % in roughing cycle
T-pocket tool
S-roughing spindle speed
R-roughing feed in z-axis
F- Roughing feed in x-y-axis
B- Finishing spindle speed, J- Finishing feed
Z-safety z-axis (above or out taking tool
5mm)
DESCRIPTION: SQUARE/ RECTANGULAR POCKETING
Dr. Mohammed Imran

SIMILARLY IN CIRCULAR POCKETING
G170 R P Q X Y Z I J K
G171 P S R F B J
G170
R-position of tool to start cycle i.e. 0
(surface job)
P-when p is ‘0’ then cycle is rough
(allowance)
Q-peck or cut increment (4 pecks each of
0.5 mm)
X-pocket center in x-axis
Y- Pocket center in y-axis
Z-pocket base from job surface
I-pocket side finishing allowance (0-0.5) J-
Pocket base finish allowance (0-0.5)
K-radius of pocket
G171
P-cut width % in roughing cycle
S-roughing spindle speed
R-roughing feed in z-axis
F- Roughing feed in x-y-axis
B- Finishing spindle speed, J- Finishing feed
Dr. Mohammed Imran

Lathe Canned Cycles Syntax And Its Description
Dr. Mohammed Imran

3.3 Programming of simple components in turning, drilling and milling systems
3.3.1 Milling Programming
Dr. Mohammed Imran

3.3 Programming of simple components in turning,
drilling and milling systems
3.3.2 Turning Programming
Dr. Mohammed Imran

3.3 Programming of simple components in turning, drilling
and milling systems
3.3.2 Turning Programming
Dr. Mohammed Imran

3.3 Programming of simple
components in turning, drilling
and milling systems
3.3.3 Drilling Programming
Dr. Mohammed Imran

3.5 Computer-assisted part programming
 Manual part programming can be time consuming, tedious, and subject to errors for parts possessing
complex geometries or requiring many machining operations. A number of NC part programming
language systems have been developed to accomplish many of the calculations that the
programmer would otherwise have to do. The program is written in English-like statements that are
subsequently converted to the low-level machine language Using this programming arrangement, the
various tasks are divided between the human part programmer and the computer.
 The automatically programmed tool system (APT) The APT project was a pioneering effort, not
only in the development of NC technology, but also in computer programming concepts, computer
graphics, and computer-aided design (CAD). Ross envisioned a part programming system in which
graphics, and computer-aided design (CAD). Ross envisioned a part programming system in which
(1) the user would prepare instructions for operating the machine tool using English-like words, (2)
the digital computer would translate these instructions into a language that the computer could
understand and process, (3) the computer would carry out the arithmetic and geometric calculations
needed to execute the instructions, and (4) the computer would further process (post-process) the
instructions so that they could be interpreted by the machine tool controller.
 The part programmer’s Job. In computer-assisted part programming, the machining instructions are
written in English-like statements that are subsequently translated by the computer into the low-level
machine code that can be interpreted and executed by the machine tool controller. The two main
tasks of the programmer are (1) defining the geometry of the part and (2) specifying the tool path
and operation sequence.
Dr. Mohammed Imran

3.5.1 Defining the geometry
The simplest geometric element is a point, and the simplest way to define a point is by means of its
coordinates; for example,
Pi = POINT/ x, y, z
Where I is 1,2,3,4....... Point position, the point is identified by a symbol (P4), and its coordinates are
given in the order x, y, z in millimeters (x = 35 mm, y = 90 mm, and z = 0).
A line can be defined by two points P1&P2, as in the following:
Cont….
A line can be defined by two points P1&P2, as in the following:
L1 = LINE/P1, P2
where L1 is the line defined in the statement, and P1 and P2 are two previously defined points. And
finally,
A circle can be defined by its center location and radius,
C1 = CIRCLE/CENTER, P8, RADIUS, 30
where C1 is the newly defined circle, with center at previously defined point P8 and radius = 30 mm.
The APT language offers many alternative ways to define points, lines, circles, and other geometric
elements.
Define plane
PL1 = PLANE/ P1, P2, P3
Dr. Mohammed Imran

3.5.2 Motion Statements
It is in general format
Motion command / descriptive data
GOTO/P1
Cont….
Initially position given by FROM/TARG or FROM/P0
For drilling operation GODLTA/x,y,z
Syntax
GODLTA/P1
GODLTA/0,0,-1
GODLTA/0,0,+1
GODLTA/P2
GODLTA/0,0,-1
GODLTA/0,0,+1
Dr. Mohammed Imran

Problem-1 on Computer-assisted part programming
Figure shows that PTP job which programmed
manually. Let us write APT geometry and motion
statement necessary to perform the drilling portion
of this job. We will set the plane define by z=0
about ¼ in . above the part surface. The part will
be assumed to be ½ in. thick.
Solution:
P1 = POINT/1.0, 2.0, 0.0
P2 = POINT/1.0, 1.0, 0.0
P3 = POINT/3.5, 1.5, 0.0
P0 = POINT/-1.0, 3.0, +2.0
FROM/P0
Cont….
GOTO/P1
GODLTA/0,0,-1.0
GODLTA/0,0,+1.0
GOTO/P2
GODLTA/0,0,-1.0
GODLTA/0,0,+1.0
GOTO/P3
GODLTA/0,0,-1.0
GODLTA/0,0,+1.0
GOTO/P0
Dr. Mohammed Imran

Cutter radius compensations
Cutter Compensation:
allows you to program the geometry not the tool path is
useful when you don’t have the right end-mill is helpful in
tweaking your part size allows you to compensate for tool
wear is generally a neat and powerful thing to know about
compensation
4.1 Understanding Cutter Compensation
Cutter compensation is one of the most useful things to know
Cutter compensation is one of the most useful things to know
when CNC machining. Cutter compensation allows you to
program the geometry and not worry about the toolpath. It
also allows you to adjust the size of your part, based on the
tool radius used to cut your part. This is useful when you can’t
find a cutter of the proper diameter. This is best explained in
the graphic below.
The solid circle is the nominal sized tool. The dashed circle is
an undersized tool, and the dash- dot circle is the oversized
tool. With a little imagination, you can see all the possibilities
for tweaking your part, or getting your part made with any
size end-mill.
Dr. Mohammed Imran

Cutter radius compensations
4.2 TURNING CUTTER COMPENSATION ON AND OFF
It is important to note that cutter compensation becomes active after the next line
move or rapid that is at least the length of the tool radius. Failure to account for
this will give a funny part. A good method around this is to zero your part and
program a move away from the part in the X and Y direction equal to the tool
radius. Then move back to 0, 0, and then continue cutting your profile. See the
graphic below.
Note the tool center is now perpendicular and to the left of point
Cont….
Note the tool center is now perpendicular and to the left of point
To turn cutter compensation off, you must do a ramp off move similar to the ramp
on move. Again, send the tool off in the X and Y direction a distance equal to the
tool radius. For the graphic above, after reaching 0,0 turn off cutter compensation
and ramp off to A. Depending on the shape, you may have to go beyond 0,0 to
eliminate any ‘nurkies’(a nurkie is an unintentional over or under cut left by the
tool). This terminates cutter compensation, and you can go on to something else.
There are three G-Codes involved in using cutter comp : G41 initiates cutter comp
to the left of the path; G42 initiates cutter comp to the right of the path; and G40
cancels cutter compensation
Finish and accuracy is usually better when you climb cut.
Dr. Mohammed Imran

Chapter-9 Robot Technology
Robotics History
 1922 Czech author Karel Capek wrote a story called Rossum’s Universal Robots and
introduced the word “Rabota”(meaning worker)
 1954 George Devol developed the first programmable Robot.
 1955 Denavit and Hartenberg developed the homogenous transformation matrices
 1962 Unimation was formed, first industrial Robots appeared.
 1973 Cincinnati Milacron introduced the T3 model robot, which became very popular in
industry.
industry.
 1990 Cincinnati Milacron was acquired by ABB
Robot Classification
The following is the classification of Robots according to the Robotics Institute of America
 Variable-Sequence Robot : A device that performs the successive stages of a task
according to a predetermined method easy to modify
 Playback Robot :A human operator performs the task manually by leading the Robot
 Numerical Control Robot : The operator supplies the movement program rather than
teaching it the task manually.
 Intelligent Robot : A robot with the means to understand its environment and the ability to
successfully complete a task despite changes to the environment.
Dr. Mohammed Imran

Chapter-9 Robot Technology
1. Introduction to Robot Technology
The field of robotics has its origins in science fiction. The term robot was derived from the English translation of a fantasy play
written in Czechoslovakia around 1920. It took another 40 years before the modern technology of industrial robotics began.
Today Robots are highly automated mechanical manipulators controlled by computers. We survey some of the science fiction
stories about robots, and we trace the historical development of robotics technology. Let us begin our chapter by defining the term
robotics and establishing its place in relation to other types of industrial automation.
Robotics: - Robotics is an applied engineering science that has been referred to as a combination of machine tool technology and
computer science. It includes machine design, production theory, micro electronics, computer programming & artificial intelligence.
OR
"Robotics" is defined as the science of designing and building Robots which are suitable for real life application in automated
manufacturing and other non-manufacturing environments.
manufacturing and other non-manufacturing environments.
Industrial robot: - The official definition of an industrial robot is provided by the robotics industries association (RIA). Industrial
robot is defined as an automatic, freely programmed, servocontrolled, multi-purpose manipulator to handle various operations of
an industry with variable programmed motions.
Automation and robotics:- Automation and robotics are two closely related technologies. In an industrial context, we can dean
automation as a technology that is concerned with the use of mechanical, electronic, and computer-based systems in the operation
and control of production Examples of this technology include transfer lines. Mechanized assembly machines, feedback control
systems (applied to industrial processes), numerically controlled machine tools, and robots. Accordingly, robotics is a form of
industrial automation.
Ex:- Robotics, CAD/CAM, FMS, CIMS
 Some of the qualities that make industrial robots commercially and technologically important are the following:
 Robots can be substituted for humans in hazardous or uncomfortable work environments.
 A robot performs its work cycle with a consistency and repeatability that cannot be attained by humans.
 Robots can be reprogrammed. When the production run of the current task is completed, a robot can be reprogrammed and equipped with
the necessary tooling to perform an altogether different task.
 Robots are controlled by computers and can therefore be connected to other computer systems to achieve computer integrated
manufacturing. Dr. Mohammed Imran

Robot anatomy
The arm or manipulator of an industrial robot consists of a series of joints and links. Robot
anatomy is concerned with the types and sizes of these joints and links and other aspects of
the manipulator’s physical construction, such as Joints and links, Common robot configurations,
Robot control systems, Accuracy and repeatability, End effectors, Sensors in robotics
discussed below;
 Manipulator / Rover : This is the main body of the Robot and consists of links, joints and
structural elements of the Robot.
structural elements of the Robot.
 End Effector : This is the part that generally handles objects, makes connection to other
machines, or performs the required tasks. It can vary in size and complexity from a
endeffector on the space shuttle to a small gripper.
 Acutators : Actuators are the muscles of the manipulators. Common types of actuators
are servomotors, stepper motors, pneumatic cylinders etc.
 Sensors : Sensors are used to collect information about the internal state of the robot or
to communicate with the outside environment. Robots are often equipped with external
sensory devices such as a vision system, touch and tactile sensors etc which help to
communicate with the environment
 Controller : The controller receives data from the computer, controls the motions of the
actuator and coordinates these motions with the sensory feedback information.
Dr. Mohammed Imran

2.1 Joints and links
 A robot’s joint, or axis as it is also called in robotics, is
similar to a joint in the human body: It provides relative
motion between two parts of the body.
 Robots are often classified according to the total number
of axes they possess.
 Connected to each joint are two links, an input link and
an output link.
Links are the rigid components of the robot manipulator.
 Links are the rigid components of the robot manipulator.
 The purpose of the joint is to provide controlled relative
movement between the input link and the output link.
 Most robots are mounted on a stationary base on the
floor.
 Let this base and its connection to the first joint be
referred to as link 0.
 It is the input link to joint 1, the first in the series of joints
used in the construction of the robot.
 The output link of joint 1 is link 1. Link 1 is the input link
to joint 2, whose output link is link 2, and so forth.
 This joint-link numbering scheme is illustrated in Figure 1.
Figure 1 Diagram of robot
construction showing how a robot is
made up of a series of joint-link
combinations.
Dr. Mohammed Imran

2.1.1 Types of Mechanical Joints
Nearly all industrial robots have mechanical joints that can be
classified into one of five types: two types that provide translational
motion and three types that provide rotary motion. These joint types
are illustrated in Figure 2 and are based on a scheme described in.
The five joint types are
1. Linear joint (type L joint). The relative movement between the
input link and the output link is a translational telescoping motion,
input link and the output link is a translational telescoping motion,
with the axes of the two links being parallel.
2. Orthogonal joint (type O joint). This is also a translational sliding
motion, but the input and output links are perpendicular to each
other.
3. Rotational joint (type R joint). This type provides rotational
relative motion, with the axis of rotation perpendicular to the axes
of the input and output links.
4. Twisting joint (type T joint). This joint also involves rotary motion,
but the axis of rotation is parallel to the axes of the two links.
5. Revolving joint (type V joint, V from the “v” in revolving). In
this joint type, the axis of the input link is parallel to the axis of
rotation of the joint, and the axis of the output link is
perpendicular to the axis of rotation.
Figure 2 Five types of joints commonly used in
industrial robot construction: (a) linear joint (type L
joint), (b) orthogonal joint (type O joint), (c)
rotational joint (type R joint), (d) twisting joint (type
T joint), and (e) revolving joint (type V joint).
Dr. Mohammed Imran

2.2 Common robot configurations
Industrial robots come in a variety of shapes and sizes.
They are capable of various arm manipulations and they
possess different motion systems.
Classification based on Physical configurations
Four basic configurations are identified with most of the
Four basic configurations are identified with most of the
commercially available industrial robots
1. Articulated robot (jointed-arm robot),
2. Polar configuration,
3. SCARA
4. Cartesian coordinate robot and
5. Delta robot.
Dr. Mohammed Imran

2.2 Common robot configurations
Cont………
Dr. Mohammed Imran

2.3 Robot control systems,
Figure 8 Hierarchical control structure
of a robot microcomputer controller.
The actuations of the individual joints must be controlled in a coordinated fashion for the
manipulator to perform a desired motion cycle. Microprocessor-based controllers are
commonly used today in robotics as the control system hardware. The controller is
organized in a hierarchical structure as indicated in Figure 8, so that each joint has its own
feedback control system, and a supervisory controller coordinates the combined actuations
of the joints according to the sequence of the robot program. Different types of control are
required for different applications.
Robot controllers can be classified into four categories:
(1) Limited-sequence control,
(2) Playback with point-to-point control,
(3) Playback with continuous path control, and
(4) Intelligent control.
Dr. Mohammed Imran

2.3 Robot control systems, Cont………
 Limited-Sequence Control. This is the most elementary control type. It can be
utilized only for simple motion cycles, such as pick-and-place operations (i.e.,
picking an object up at one location and placing it at another location). It is usually
implemented by setting limits or mechanical stops for each joint and sequencing
the actuation of the joints to accomplish the cycle.
 Playback with Point-to-Point Control. Playback robots represent a more
 Playback with Point-to-Point Control. Playback robots represent a more
sophisticated form of control than limited-sequence robots. Playback control means
that the controller has a memory to record the sequence of motions in a given
work cycle, as well as the locations and other parameters (such as speed)
associated with each motion, and then to subsequently play back the work cycle
during execution of the program Playback with Point-to-Point Control. Playback
robots represent a more sophisticated form of control than limited-sequence
robots. Playback control means that the controller has a memory to record the
sequence of motions in a given work cycle, as well as the locations and other
parameters (such as speed) associated with each motion, and then to subsequently
play back the work cycle during execution of the program.
Dr. Mohammed Imran

2.3 Robot control systems, Cont………
 Playback with Continuous Path Control. Continuous path robots have the same playback capability as
the previous type. The difference between continuous path and point-to-point is the same in robotics as it
is in NC. A playback robot with continuous path control is capable of one or both of the following:
1. Greater storage capacity. The controller has a far greater storage capacity than its point-to-point
counterpart, so the number of locations that can be recorded into memory is far greater than for
point-to-point. Thus, the points constituting the motion cycle can be spaced very closely together to
permit the robot to accomplish a smooth continuous motion. In PTP, only the final location of the
individual motion elements are controlled, so the path taken by the arm to reach the final location is
individual motion elements are controlled, so the path taken by the arm to reach the final location is
not controlled. In a continuous path motion, the movement of the arm and wrist is controlled during the
motion.
2. Interpolation calculations. The controller computes the path between the starting point and the
ending point of each move using interpolation routines similar to those used in NC. These routines
generally include linear and circular interpolation.
 Intelligent Control. Industrial robots are becoming increasingly intelligent. In this context, an intelligent
robot is one that exhibits behavior that makes it seem intelligent. Some of the characteristics that make a
robot appear intelligent include the capacities to interact with its environment, make decisions when things
go wrong during the work cycle, communicate with humans, make computations during the motion cycle,
and respond to advanced sensor inputs such as machine vision. In addition, robots with intelligent control
possess playback capability for both PTP and continuous path control. All of these features require (1) a
relatively high level of computer control and (2) an advanced programming language to input the
decision-making logic and other “intelligence” into memory.
Dr. Mohammed Imran

2.4 Accuracy and repeatability
 Accuracy - This is determined by the resolution of the workspace. If the robot is
commanded to travel to a point in space, it will often be off by some amount, the
maximum distance should be considered the accuracy.
 Repeatability - The robot mechanism will have some natural variance in it. This means
that when the robot is repeatedly instructed to return to the same point, it will not
always stop at the same position.
 A portion of a linear positioning system axis, with showing control resolution, accuracy,
and repeatability
and repeatability
Dr. Mohammed Imran

2.5 End effectors
 Robot configurations, an end effector is usually
attached to the robot’s wrist. The end effector
enables the robot to accomplish a specific task.
Because there is a wide variety of tasks
performed by industrial robots, the end effector is
performed by industrial robots, the end effector is
usually custom-engineered and fabricated for
each different application.
 The two categories of end effectors are grippers
and tools
Dr. Mohammed Imran

2.5 End effectors
2.5.1 Grippers
 Grippers are end effectors used to grasp and manipulate objects during the work cycle.
The objects are usually work parts that are moved from one location to another in the cell.
Machine loading and unloading applications fall into this category. Owing to the variety of
part shapes, sizes, and weights, most grippers must be custom designed.
Cont………..
Figure 10 Mechanical Gripper
Types of grippers used in industrial robot applications include the following:
 Mechanical grippers, consisting of two or more fingers that can be actuated by the
robot controller to open and close on the work part (Figure 10 shows a two-finger
gripper)
 Vacuum grippers, in which suction cups are used to hold flat objects
 Magnetized devices, for holding ferrous parts
Dr. Mohammed Imran

2.5 End effectors
2.5.1 Grippers
 Adhesive devices, which use an adhesive substance to hold a flexible
material such as a fabric. Simple mechanical devices, such as hooks and
scoops. Mechanical grippers are the most common gripper type. Some of
the innovations and advances in mechanical gripper technology include:
 Dual grippers, consisting of two gripper devices in one end effector for
machine loading and unloading. With a single gripper, the robot must
reach into the production machine twice, once to unload the finished part
and position it in a location external to the machine, and the second time
to pick up the next part and load it into the machine. With a dual
gripper, the robot picks up the next work part while the machine is still
Cont………..
gripper, the robot picks up the next work part while the machine is still
processing the previous part. When the machine cycle is finished, the
robot reaches into the machine only once: to remove the finished part and
load the next part. This reduces the cycle time per part.
 Interchangeable fingers that can be used on one gripper mechanism. To
accommodate different parts, different fingers are attached to the
gripper
 Sensory feedback in the fingers that provide the gripper with
capabilities such as (1) sensing the presence of the work part or (2)
applying a specified limited force to the work part during gripping (for
fragile work parts).
 Multiple-fingered grippers that possess the general anatomy of a human
hand.
 Standard gripper products that are commercially available, thus reducing
the need to custom-design a gripper for each separate robot application.
Dr. Mohammed Imran

2.5 End effectors
2.5.2 Tools
A robot is required to manipulate a tool to
perform an operation on a work part. Here the
tool acts as end-effectors. Spot-welding tools,
Cont………..
tool acts as end-effectors. Spot-welding tools,
arc-welding tools, spray painting nozzles, and
rotating spindles for drilling and grinding are
typical examples of tools used as end-effectors
Dr. Mohammed Imran

2.6 Sensors in robotics.
Sensors used in industrial robotics can be classified into two categories:
(1) Internal and
(2) External.
 Internal sensors are components of the robot and are used to control
the positions and velocities of the robot joints. These sensors form a
feedback control loop with the robot controller. Typical sensors used to
feedback control loop with the robot controller. Typical sensors used to
control the position of the robot arm include potentiometers and optical
encoders. Tachometers of various types are used to control the speed
of the robot arm.
 External sensors are external to the robot and are used to coordinate
the operation of the robot with other equipment in the cell. In many
cases, these external sensors are relatively simple devices, such as limit
switches that determine whether a part has been positioned properly
in a fixture or that a part is ready to be picked up at a conveyor.
Dr. Mohammed Imran

Other situations require more advanced sensor technologies, including
the following:
 Tactile sensors. These are used to determine whether contact is
made between the sensor and another object. Tactile sensors can be
divided into two types in robot applications: (1) touch sensors and
(2) force sensors. Touch sensors indicate simply that contact has been
made with the object. Force sensors indicate the magnitude of the
Cont ………
made with the object. Force sensors indicate the magnitude of the
force with the object. This might be useful in a gripper to measure
and control the force being applied to grasp a delicate object.
 Proximity sensors. These indicate when an object is close to the
sensor. When this type of sensor is used to indicate the actual
distance of the object, it is called a range sensor.
 Optical sensors. Photocells and other photometric devices can be
utilized to detect the presence or absence of objects and are often
used for proximity detection.
Dr. Mohammed Imran

 Machine vision. Machine vision is used in robotics for
inspection, parts identification, guidance, and other
uses, provides a more complete discussion of machine
vision in automated inspection. Improvements in
programming of vision-guided robot (VGR) systems
have made implementations of this technology easier
Cont ………
have made implementations of this technology easier
and faster and machine vision is being implemented as
an integral feature in more and more robot
installations, especially in the automotive industry.
 Other sensors. A miscellaneous category includes other
types of sensors that might be used in robotics, such as
devices for measuring temperature, fluid pressure, fluid
flow, and electrical voltage, current.
Dr. Mohammed Imran

2.7 Robot industrial applications:
Robots are used in a wide field of applications in industry. Most of the current
applications are in manufacturing. The applications can usually be classified into
one of the following categories:
(1) Material handling,
(2) Processing operations, and
(3) Assembly and inspection.
Material handling,
 Material handling,
In material handling applications, the robot moves materials or parts from one
place to another. To accomplish the transfer, the robot is equipped with a
gripper that must be designed to handle the specific part or parts to be
moved. Included within this application category are (1) material transfer and
(2) machine loading and/or unloading.
 Material Transfer. These applications are ones in which the primary purpose
of the robot is to move parts from one location to another. In many cases,
reorientation of the part is accomplished during the move. The basic
application in this category is called a pick-and-place operation, in which the
robot picks up a part and deposits it at a new location.
Dr. Mohammed Imran

 Machine Loading and/or Unloading. In machine loading and/or
unloading applications, the robot transfers parts into and/or from a
production machine. The three possible cases are ,
(1) machine loading, in which the robot loads parts into the production
machine, but the parts are unloaded from the machine by some other
means;
(2) machine unloading, in which the raw materials are fed into the
Cont ………
(2) machine unloading, in which the raw materials are fed into the
machine without using the robot, and the robot unloads the finished
parts; and
(3) machine loading and unloading, which involves both loading of the
raw work part and unloading of the finished part by the robot.
Industrial robot applications of machine loading and/or unloading
include the following processes:
 Die casting. The robot unloads parts from the die casting machine.
Peripheral operations sometimes performed by the robot include dipping
the parts into a water bath for cooling.
Dr. Mohammed Imran

 Plastic molding. Plastic molding is similar to die casting. The robot unloads molded
parts from the injection molding machine.
 Metal machining operations. The robot loads raw blanks into the machine tool
and unloads finished parts from the machine. The change in shape and size of the
part before and after machining often presents a problem in end effector design,
and dual grippers are often used to deal with this issue.
 Forging. The robot typically loads the raw hot billet into the die, holds it during
Cont ………
 Forging. The robot typically loads the raw hot billet into the die, holds it during
the forging strikes, and removes it from the forge hammer. The hammering action
and the risk of damage to the die or end effector are significant technical
problems.
 Pressworking. Human operators work at considerable risk in sheet-metal press-
working operations because of the action of the press. Robots are used to substitute
for the workers to reduce the danger. In these applications, the robot loads the
blank into the press, then the stamping operation is performed, and the part falls
out of the machine into a container.
 Heat-treating. These are often relatively simple operations in which the robot loads
and/or unloads parts from a furnace.
Dr. Mohammed Imran

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