The document provides an introduction to computer numerical control (CNC) machines, including their history, components, programming, and advantages. It discusses how CNC machines work by taking in programs to control machine tools along various axes. The inputs, control unit, drives, feedback systems and displays are described. Examples of CNC machine types and their uses in industry are given. The document concludes that CNC machines improve efficiency in large-scale manufacturing by reducing labor and producing parts more accurately compared to manual machines.

1. BUNDELKHAND INSTITUTE OF ENGINEERING AND TECHNOLOGY
JHANSI
BY :
NAME
1
INDUSTRIAL TRAINING SEMINAR
INTRODUCTION TO CNC MACHINE
From
BHEL JHANSI

2. INDEX
2
Introduction of BHEL
Products
History
Introduction to CNC
Need of CNC
Types of CNC Machine
Block Diagram of CNC Machines
Working of CNC Machine
Elements of CNC
 Input devices
 Machine control unit
 Driving System
 Feedback System
 Display Unit
 CNC Programming Basics
 Advantages
 Challenges
 Conclusions

3. BHEL
2
 BHEL is India's largest engineering and manufacturing
Enterprise.
 Established in 1956.
 Got 'Maharatna' status by the Government of India on 1
February 2013.
 More than 150 project sites across India and abroad.
 The company has added more than 1,24,000 MW to the
country's installed power generating capacity so far.

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PRODUCTS
 Locomotive Plant
 Boilers Auxiliaries Plant.
 Transformer.
 Power electronics.
 Electrical machines.
 Insulator Plant
 Oil field equipment.

5. HISTORY
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 The first NC machines were built in the 1940s and 1950s by Prof.
John T Parson.
 US Air Force teamed up with MIT to develop a programmable
milling machine (1949).
 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.

6. INTRODUCTION
6
 Numerical control is a method of automatically
operating a manufacturing machine based on a
code of letters, numbers, and special characters.
 The numerical data required to produce a part is
provided to a machine in the form of a program,
called part program or CNC program.
 The program is translated into the appropriate
electrical signals for input to motors that run the
machine.

7. NEED OF CNC
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 Increase production rate.
 Stabilize manufacturing costs.
 Highly accurate over traditional machines.
 More operations can be performed with each
setup Repeatability, reduced scrap loss, and high
production rates.

8. TYPES OF CNC MACHINES
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There are many different types of CNC Machines used in industry, Such as:
 Mills and Machining Centers
 Lathes and Turning Centers.
 Drilling Machines
 Wire cut Machines.
 Flame and Laser-Cutting Machines

9. BLOCK DIAGRAM
9

10. WORKING OF CNC
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 All computer controlled machines are able to accurately and repeatedly control
motion in various directions. Each of these directions of motion is called an axis.
Depending on the machine type there are commonly two to five axes.

11. Open loop and Closed loop controls
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12. Elements of CNC Machine
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 Input Device
 Machine Control Unit
 Machine Tool
 Driving System
 Feedback Devices
 Display Unit

13. Input Devices
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 Floppy Disk Drive.
 USB Flash Drive.
 Serial communication.

14. Machine Control Unit
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 Data Processing Unit
 On receiving a part programme, the DPU firstly interprets and encodes the
part programme into internal machine codes.
 Control Loop Unit
 Data from the DPU are converted into electrical signals in the CLU to control
the driving system to perform the required motions.

15. Driving System
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 This system usually uses electric motors although hydraulic motors are
sometimes used for large machine tools.
 DC servo motor
 The principle of operation is based on the rotation of an armature winding in
a permanently energized magnetic field.
 Stepper Motor
 A stepper motor is a device that converts the electrical pulses into discrete
mechanical rotational motions of the motor shaft

16. FEEDBACK DEVICES
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 Positional Feed Back Devices
 A linear transducer is a device mounted on the machine table to
measure the actual displacement of the slide.
 Velocity Feedback Device
 The actual speed of the motor can be measured in terms of voltage
generated from a tachometer mounted at the end of the motor shaft.

17. Display Unit
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The Display Unit serves as an interactive device between the machine and the
operator.
 Operator Control Panel
To facilitate two-way communication between the user, CNC system and the machine
tool.
 Video Display Unit (VDU).
 Keyboard.
 Machine Control Panel (MCP)
It is the direct interface between operator and the NC system, enabling the operation
of the machine through the CNC system.

18. CNC Programming Basics
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 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.

19. Advantages
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 Easier to program;
 Easy storage of existing programs;
 Easy to change a program
 Avoids human errors
 CNC machines are safe to operate
 Complex geometry is produced as cheaply as simple ones
 Usually generates closer tolerances than manual machines

20. Challenges
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 Costly setup, skilled operators
 Computers, programming knowledge required
 Maintenance is difficult

21. Conclusion
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 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.
 BHEL 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.

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