Cnc machine

CNC Machine
Machining Technology 2

Group Members:
Junaid Fakhar (2k15-MET-26)
Tehseen Mustafa Owaisi (2k15-MET-28)
Azhar Aslam (2k15-MET-36)
M. Usman (2k15-MET-37)
Jamshaid Ali (2k15-MET-38)

HISTORY AND INTRODUCTION:
Azhar Aslam (2k15-MeT-36)

1. CNC INTRODUCTION
2. HISTORY
3. ELEMENTS OF CNC.
4. BLOCK DIAGRAM OF
CNC
5. TYPES OF CNC MACHINE
6. HOW CNC WORKS?
7. FEATURES OF CNC
MACHINES
CONTENTS:
8. CNC PROGRAMMING
BASICS
9. COMMON FORMAT OF
A BLOCK
10. PROGRAMMING KEY
LETTERS
11. ADVANTAGES
12. CHALLENGES
13. CONCLUSION
14. REFERENCES

CNC INTRODUCTION:
• A numerical control system in which the data handling, control
sequences, and response to input is determined by an on-board
computer system at the machine tool.
• CNC machine is a machine which does machining process with the help
of computerized control units which give it instructions regarding:
1. Tool Control: Tool and tool parameters
2. Units, incremental or absolute positioning
3. Feed rate and spindle speed
4. Coordinate System
5. Coolant Control: On/Off, Flood, Mist
6. Coordinates: X,Y,Z

• The first NC machines were
built in the 1940s and 1950s by
Prof. John T Parson.
• CNC machine came into
existence after evolution of
computer around 1980.
• Modern CNC Machine are
improving further as the
technology is changing with a
variety of functions according to
applications.
HISTORY:

ELEMENTS OF CNC MACHINE
• A CNC machine consist of following 6 major elements:
i. Input Device
ii. Machine Control Unit
iii. Machine Tool
iv. Driving System
v. Feedback Devices
vi. Display Unit

HOW CNC WORKS?
• HOW CNC WORKS
• Controlled by G and M codes.
• These are number values and co-ordinates.
• Each number or code is assigned to a particular operation.
• Typed in manually to CAD by machine operators.
• G & M codes are automatically generated by the computer
software.

FEATURES OF CNC MACHINE:
• The tool or material moves automatically.
• Tools can operate in 1-5 axes.
• Larger machines have a machine control unit (MCU) which
manages operations.
• Movement is controlled by motors (actuators).
• Feedback is provided by sensors (transducers)
• Tool magazines are used to change tools automatically.

CNC PROGRAMMING BASICS:
• CNC instructions are called part program commands.
• When running, a part program is interpreted one command line at
a time until all lines are completed.
• Commands, which are also referred to as blocks, are made up of
words which each begin with a letter address and end with a
numerical value.

CNC PROGRAMMING:
• Important things to know:
 Coordinate System
 Units, incremental or absolute positioning
 Coordinates: X,Y,Z, RX,RY,RZ
 Feed rate and spindle speed
 Coolant Control: On/Off, Flood.
 Tool Control: Tool and tool parameters

Programming consists of a series
of instructions in form of letter codes
•Preparatory Codes:
G codes- Initial machining setup and
establishing operating conditions
N codes- specify program line number
to executed by the MCU
•Axis Codes: X,Y,Z
Used to specify motion of the slide along
X, Y, Z direction
•Feed and Speed Codes: F and S
Specify feed and spindle speed
•Tool codes: T – specify tool number
•Miscellaneous codes – M codes
For coolant control and other activities

N50 G90 G01 X1.40Y2.25 F10 S1500 T01 M03
Sequence# Preparatory Function Dimension Words Feed Rate Spindle Function Tool Function Misc. Function
COMMON FORMAT OF A BLOCK:

PROGRAMMING KEY LETTERS:
• O - Program number (Used for program identification)
• N - Sequence number (Used for line identification)
• G - Preparatory function
• X - X axis designation
• Y - Y axis designation
• Z - Z axis designation

• R - Radius designation
• F – Feed rate designation
• S - Spindle speed designation
• H - Tool length offset designation
• D - Tool radius offset designation
• T - Tool Designation
• M - Miscellaneous function

Programming Example
(Cylindrical Part)
O0077
N0005 G28 U0.0 W0.0;
N0010 T0202;
N0020 G97 S1500 M03;
N0030 G00 X50.0 Z1.0 ;
N0040 G71 U1.0 R2.0;
N0050 G71 P0060 Q00 U0.5 W0.2 F0.2;
N0060 G01 X13.0;
N0070 X15.0 Z-1.0;
N0080 Z-30.0N0090 X23.0N0100 X25.0 Z-50.0;
N0110 X50.0;
N0120 G70 P0060 Q0110 S2500 F0.1;
N0130 G28 U0.0 W0.0,
N0140 M30

DIFFERENT TYPES OF CNC MACHINES:
Jamshaid Ali (2k15-MeT-38)

• CNC Lathe Machine
• CNC Milling Machine
• CNC Router Machine
• Plasma.
• Laser Cutting machine.
• 3D PRINTER.
• Flame cutting machine.
• Electric Discharge Machine.
• Water Jet.
• CNC Punch Press.
TYPES OF CNC MACHINE:

CNC LATHE MACHINE:
• Use for facing, turning ,
reaming, drilling, finishing
etc.,
• Automatically operated with
the help of G&M codes.

CNC MILLING MACHINE:
• The milling machines are also known as
the multi-tasking machines (MTMs) which
are multi-purpose machines capable of
milling and turning the materials as well.
• The milling machine has got the cutter
installed up on it which helps in removing
the material from the surface of the
workpiece. When the material gets cooled
down then it is removed from the milling
machine.

CNC ROUTER MACHINE:
• CNC Routers are a very common piece of machinery you will see a
lot when learning about CNC.
• These are machines built exclusively to be operated by CNC
technology and typically have no human interface other than
through the computer.
• Routers are generally for producing larger dimension parts and
more commonly built with the idea of cutting wood, plastics and
sheet metal in mind.
• Routers also are most commonly found in a 3 axis Cartesian
coordinate setup (X, Y and Z).

PLASMA:
• CNC plasma cutters are very similar to
CNC routers in size and setup.
• However plasma cutters don’t require
as much of a powerful set up because
as opposed to dragging around a
spinning tool in material they fly
above the table with a plasma torch.
• Plasma cutters are made for cutting 2
dimensional profile shapes into sheet
metal.

Laser, 3d Printer, Flame cutting Machines:
JUNAID FAKHAR (2k15-MeT-26)

CNC LASER CUTTER:
• CNC laser cutters follow the same principle as
the plasma cutter, except they use a powerful
laser to do the cutting.
• Laser cutters are often good for cutting
wood,plastic and metal; each will need a
different strength of laser suited for the
material depending on the hardness and
thickness.

3D PRINTER:
• A 3D printer uses a similar set up as a CNC router or
• laser cutter, but unlike those machines it does additive
• machine as opposed to subtractive machining.
• • Instead of starting with a solid piece of material and
• removing bits of that material to end up with the
• desired part, the 3D printer starts with a blank canvas
• and builds a part up layer-by-layer.
• • The 3D printer does this either by using an extruder
• that pushes a material (typically plastic) out from a
tiny
• nozzle, or by using a laser that quickly solidifies a
• powder or liquid

Flame Cutting?
• The process often called Flame Cutting is
known by many names, such as Oxy
Acetylene Cutting,Oxy Fuel Gas Cutting,
Oxygen Burning, and Steel Burning.
• The process is now about 111-112 years old
as it was patented in 1901 by Thomas
Fletcher. One of the first commercial
applications was what the British referred
to as “an unauthorized bank entry”, or a
“safe cracking”.

How does it work?
• The process is a Thermo-Chemical Process requiring a source of intense
heat, referred to as “Preheat”, and pure oxygen.
• The process can be used for cutting/severing many different materials
with the basic requirement that the oxide formed must have a lower
melting point than the base material to be cut.
• The process can cut from sheet metal thicknesses to 100 inch material
but thin materials are very challenging to flame cut.
• The process for all thicknesses is the same and that is the material must
be “preheated” to a
• temperature of 1,600-1,800 degrees F, then the pure Oxygen is
discharged into the preheated area
• and the steel is then oxidized or burned, hence the term “burning”.

Applications of flame cutting method:
• 1. It is used to cut many layers of thin sheets also known as stack
cutting to reduce the cost and time of production effectively.
2. Flame cutting is used to groove weld joint metal designs and to
prepare the edges of metal plates.
3. It can be used to cut risers, rivets and gates from castings.
4. Flame cutting is also used for salvage work and to pierce slots and
holes of different sizes in steel plates.
5. Also used to cut work pieces of small sizes from large metal plates
for further usage in production.

Advantages of Flame cutting method:
1. It can cut metals into small shapes and sizes that is otherwise
difficult to be machined by other mechanical methods.
2. Equipments used in flame cutting process are portable and can
be used effectively for field work.
3. Flame cutting machines with multiple torches can cut number of
steel profile pieces simultaneously.
4. This process of steel cutting is faster as compared to other
mechanical cutting methods.
5. As compared to other mechanical cutting methods, the cost of
using flame cutting method is rather low and cost effective.

Disadvantages of flame cutting method:
1. This method is limited to the cutting of steel and cast iron
materials only.
2. The dimensional tolerances as compared to other mechanical
cutting methods are poor.
3. The heat and red hot slag expelled during this metal
cuttingmethod present fire and burn hazards to plant and workers.
4. Proper fume control and adequate ventilation is must for the
place of cutting.

CNC Flame Cutting Machine
Standard Features:
• Cutting width available 1.25 and 1.5 meter
• Cutting length available from 2.0 meter to 3.0
meter
• Longitudinal and trans verse energy feed drag
chains, hose/ cable clean and move smooth.
• • DC Stepper drive amplifiers for years of
maintenance free operation.
• • DC Stepper motors for wide s peed range with
accurate s peed control
• • CNC controller allows entering the program
directly on the s ys tem or transfer files through
USB drive

Standard Features:
• Single torch s tation available
• Maximum machine s peed: 5000 mm/min
• Adjustable steel mounting pads for adjusting height, level,
straightness
• Oxy Fuel Edge Prep Station - for straight line bevel cuts in either X
or Y direction
• Oxy fuel cutting thicknes s : 5 mm - 100mm.

5 Axis CNC, EDM:
Tehseen Mustafa Owaisi (2k15-MeT-28)

5 AXIS CNC MACHINE:
• 5 axis CNC machines add two rotary axes
to the typical three axis setup.
• The rotary axes allow much more complex
machining to produce parts that would be
impractical/impossible to do on a
“normal” CNC router or mill.

DIFFERENT AXIS SYSTEM:
• 2 Axis if all the cutting takes place in the same plane. In this case,
the cutter does not have any capability of movement in the Z
(vertical) plane. In general the X and Y axes can interpolate together
simultaneously to create angled lines and circular arcs.
• 2.5 Axis if all the cutting takes place entirely in planes parallel to
the principal plane but not necessarily at the same height or depth.
In this case, the cutter can move in the Z (vertical) plane to change
levels, but not simultaneously with the X,Y movements.
• An exception might be that the cutter can interpolate helically, that
is, do a circle in X,Y while moving simultaneously in Z to form a helix
(for example in thread milling).

 A subset of the above is that the machine can interpolate any 2 axes
together simultaneously, but not 3.
 This does make a limited number of 3D objects possible, by cutting in
the XZ or YZ planes, for example, but is much more limited than full
3 axis interpolation.
 3 Axis if your cutting requires simultaneous controlled movement of the X,Y,Z
axes, which most free-form surfaces require.
 4 axis if it includes the above plus 1 rotary axis movement. There are two
possibilities:
4 axis simultaneous interpolation (also known as true 4th axis). Or just 4th
axis positioning, where the 4th axis can reposition the part between 3 axis
operations, but does not actually move during the machining.
 5 axis if it includes the above plus 2 rotary axis movements. Besides true 5
axis machining (5 axes moving simultaneously while machining), you also
often have 3 plus 2 or 3 axis machining + 2 separate axes positioning only, as
well as in rarer cases 4 plus 1 or continuous 4 axis machining + a single 5th
axis positioning only

Electric Discharge Machining:
• In EDM the metal is removed due to
erosion caused by rapidly occurring
discharge between the tool and
workpiece.
• The mechanism involved in Material
removal is melting and evaporation.
• In EDM, Positive terminal erodes out faster
so work piece is made as anode.
• Negative terminal is connected to tool
which acts as a cathode.

Dielectric Fluid:
• The use of liquid dielectric fluid provides the
following main advantages
• It acts as Vehicle to drive away the chips and
thus preventing them from sticking to the
surface of tool.
• It helps in increasing the Metal Removal Rate
(MRR) by promoting spark between tool and
work.
• It acts as coolant medium.

Applications:
• EDM are most commonly used for machining
• Blind , complex cavities.
• Hard material dies.
• Making holes in dies.

Water jet, Punch Press Machines:
M.Usman (2k15-MeT-37)

WATER JET:
• Water jet travels at velocities as high as 900 m/s.
• When the jet of water strikes a work piece surface, the erosive
force of water removes the material rapidly.
• The water, in this case, acts like a saw and cuts a narrow groove in
the work piece material.

• When the a high pressure (150-1000 MPa) and high velocity
(540-1400 m/s) of water jet comes out of nozzle and strikes the
work piece of the material, its kinetic energy is converted into
pressure energy including high stresses in the work material.
When this induced stress exceeds the ultimate shear stress of the
material, small chips of the work piece material get loosened and
fresh surface is exposed.
• The fluid flow rate is typically from 0.5 to 2.5 l/min.
• Water is the most common fluid used, but additives such as
alcohols, oil products and glycerol are added when they can be
dissolved in water to improve the fluid characteristics.

HOW WATER JET WORKS?
• High pressure (60,000 psi), which when bombarded on the work
piece erodes the material.
• A high velocity water jet when directed at a target in such a way
that, its velocity in virtually reduced to zero on striking the
surface. Because of this water jet will make a hole in the material
if the pressure is high enough.

WHY USE WATER JET?
• It can cut almost everything, with greater efficiency and
productivity.
• It is one of the fastest growing major machine tool processes in
the world due to its versatility and ease of operation.
• Water jets cut accurately, reduced scrap-saving money through
greater material utilization.

• PURE WATER JET
TYPES OF WATER JET:
• ABRASIVE WATER JET

Punch Press:
• “It is a machine by
which we can do
cutting and non cutting
process by applying
force without removing
chip on metallic or
nonmetallic sheet.”

Advantages of CNC:
i. - Easier to program;
ii. - Easy storage of existing programs;
iii. - Easy to change a program
iv. - Avoids human errors
v. - CNC machines are safe to operate
vi. - Complex geometry is produced as cheaply as simple ones
vii. - Usually generates closer tolerances than manual machines

Disadvantage:
i. COSTLY SETUP, SKILLED OPERATORS.
ii. COMPUTERS, PROGRAMMING KNOWLEDGE REQUIRED.
iii. MAINTENANCE IS DIFFICULT.

CONCLUSION:
• The advantage of a CNC system are that the operation of a
conventional machine is removed and the part production is made
automatic.
• It reduces the labor work and hence highly efficient in the
manufacturing process.
• Generally uses CNC machines to achieve its manufacturing targets.
For manufacturing works of large scale it is very difficult to work
with manual machines as they are time consuming.
• CNC machines have their wide scope because they are easy to
handle, the work becomes easier and jobs are done with
perfection.

REFERENCES:
• Manual of CNC from BHEL Jhansi
• http://en.wikipedia.org/wiki/computer_numerical_control
• http://www.motioncontrol.com/articles/gearheads-
modularspindle-drives
• http://www.seminarprojects.com/cnc

Cnc machine

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