CNC machines are controlled by computers to perform machining operations. A CNC machine system consists of a program, tape reader, mini-computer, servo system, and the machine tool itself. The program is fed into the control unit which directs the servo system to control the machine's motions. Common types of CNC machines include lathes, milling machines, lasers, routers, plasma cutters, and 3D printers. CNC machines offer advantages like higher precision and accuracy, reduced labor costs, and the ability to easily change or modify programs.

1. October 27,
2019
CNC Machine: Types, Parts, Advantages, Disadvantages,
Applications, and Specifications (With PDF)
learnmechanical.com/cnc-machine/
As we know machines like lathe, Milling, Drilling the operation are performed manually and
there is more involvement of humans to perform and time taking is high average precision
and accuracy. So to overcome this problem, the machine manufactured is CNC which is
known as Computer Numerically controlled. let’s understand in detail and also at the end
of the article I will give a PDF downloadable link also.
There is a written program of CNC machine, before going to operate the CNC machine. First,
we insert or feed the operation program on the CNC machine and set the workpiece on it
and start the machining process.
One more thing I would like to share you that lathe machine operation or any manual
machine operation is carried, there the heat generated between tool and workpiece. To
avoid this we have to put water or any other coolant to reduce heat.
But in the case of the CNC machine that water parts automatically set there no need to
provide manually.
Today's Topics:
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2. What is a CNC Machine?
CNC machine can be defined as the machine which is control by computer and the operation is
performed by feeding the program on it.
CNC machine operates on only two subjects which are CAD and CAM.
CAD stands for Computer-aided design. This subject helps you to learn about the design of
a machine and machines tools.
CAM stands for Computer-aided manufacturing. This subject is also similar to CAD but it
deals with manufacturing whereas CAD deals design.
Parts of CNC Machine:
A CNC machine is consists of the following parts:
Bed
Headstock
Tailstock
Tailstock quill
Footswitch or pedal
Chuck
Control panel
Tool turret
Let’s go into details.
Bed:
The bed is kind of hardened parts of a machine because The tool turret travels over the CNC
lathe bed, kind of machining can’t affect them.
Headstock:
The headstock is the main part of the machine, here the workpiece is fixed to perform an
operation and also Headstock of a CNC lathe machine has the main motor which drives the
main spindle.
Tailstock:
The tailstock is for providing extra grip to the workpiece. When the operation like knurling,
threading has performed these parts used to hold the workpiece.
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3. Tailstock quill:
This is kind of setting the workpiece between the centers.
Footswitch or pedal:
Through these pedals, CNC machinist’s open and close the chuck to grip the component, the
same way tailstock quill is taken to forward position or reversed.
Chuck:
Chuck is mounted on the main spindle. Here we fixed the workpiece.
Control panel:
The control panel is another main part of the CNC machine in which we use to set or feed
the program for the operation we perform on the workpiece.
This is also called the brain of a CNC machine.
Tool turret:
The tool is mounted on the tool turret which is used for component machining.
Tool turrets vary in shapes and the number of tools that can be mounted on them.
These are the Parts of CNC machine, now I will talk about the CNC system.
Elements of the CNC Machine system:
A CNC machining system is consists of the following elements:
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4. Program
Tape Reader
Mini-computer
Servo system
CNC machine tool
Program:
This is entered into the computer through a keyboard. These are the codes used to control
the machine.
The various CNC codes are N Code, G Code, XYZ Code, F code, etc.
Below is the table where I write all the common codes used in CNC.
Tape Reader:
This is used as a storage device where we can store the program for a particular machining
operation.
Any modification of a program can easily be done by editing the existing program as per
your requirement.
Mini-computer:
It is also called the machine control unit. It is to read interprets and converts perceived
input, that is part program into the desired movement and controls the following functions:
To start and stop the machine spindle.
Vary the spindle speed accordingly and also it can control the direction of rotation of
the spindle.
To start and stop the coolant supply.
To change the required tools as per requirements.
To change the workpiece.
To control the feed rate.
Also, the mini-computer equipped with diagnostic software which can detect any problem
and restore the machine accordingly.
Servo system:
The function of the servo system is to receive the control signal from the feedback devices
and the set output accordingly (To shaft, tools and other components of CNC machine)
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5. Block diagram of CNC Machine
Servo system mainly consists of:
1. Servo Motors
2. Feed-back devices
3. Ball screws
CNC Machine:
This is the actual machine where the finished product made. I already mentioned the parts
of the CNC machine above this heading.
This is the housing of headstock, tailstock, foot switch, chuck, and tool turret.
How CNC Machine Works?
The above all the details I have explained is all about the CNC machine.
The CNC machine works based on CAD and CAM programs and computer control.
CAD (Computer-Aided Design) is drawing software.
Also, CAD software is used to increase the productivity of the designer, improve the quality
of design, improve communications through documentation, and to create a database for
manufacturing.
Whereas, CAM (Computer-Aided Manufacturing) having two codes like G-code and M-codes
on which all the programs are written and feed into the machine to perform the various
operations. (i.e. turning, grooving operation in a lathe)
Here is the example of steps:
The first step is, write and Insert the part program which is (G and M code) into the
Machine Control Unit of the CNC machine.
Now all the data process takes place and according to the program it prepares
commands and sends it to the driving system.
The drive system controls the motion and velocity of the machine tool.
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6. The feedback system records the position and velocity measurement of the machine
tool and sends a feedback signal to the MCU.
In MCU, the feedback signals are compared with the reference signals and if there are
errors, it corrects it and sends new signals to the machine tool for the right operation
to happen.
The display unit is used to see all the commands, programs, and other important data.
Here is a Working Video of a CNC Machine:
Video Source: LA Machines
Types of CNC Machine:
CNC machines are can be classified into the following types:
CNC laser cutting machine
CNC Lathe Machine
CNC Milling Machine
CNC router Machine
CNC Plasma Cutting Machine
5- axis machine
3-D Printer
Pick and Place Machine
CNC laser cutting machine:
As the name itself indicates “Laser cutting” it means the cutting operation is carried by laser
and the operation code is fed into machine runs automatically, it is called CNC laser
cutting machine.
This machine is used for sheet cutting.
It provides a better surface finish.
Even do the complicated design can be made in this you just have to feed the program
according to it.
The machine cost is very high.
The major problem face is like when machine parts got damage it takes time to fix because
of unavailability in the market.
CNC Lathe Machine:
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7. Before moving further on the CNC Lathe machine I wanna tell you that I have covered Lathe
Machine in detail, I have discussed every possible point on the lathe machine you should
check it too.
Now moving to CNC Lathe machine.
CNC stands for Computerized numerically controlled.
This is widely used as a lathe in the present time because of its fast and accurate working. It
is one of the most advanced types.
It uses computer programs to control the machine tool. Once the program is fed into the
computer as per the program it starts operation with very high speed and accuracy.
Even do preplanned programmed machine is there in which once code is set for the various
operations it can starts operation without changing code in the next time.
A semi-skilled worker can easily operate this after the initial setup is done.
These types of lathes are also used for mass production like capstan and turret but there is
no programmed fed system.
The components manufactured by these lathes are very accurate in dimensional tolerances.
CNC Milling Machine:
I also have written an article on the Convectional Milling machine you may check that too.
As we know Milling Machine is a process of metal-removing by feeding the workpiece passes
through the rotating multipoint cutter.
This machine is used to make gears like Spur gears, and also drill the workpiece bore, and
produce slots.
The same work is performed in CNC Milling by inserting the part program into the system.
A semi-skilled worker can easily operate this after the initial setup is done.
These types of machines are also used for mass production like capstan and turret but
there is no programmed fed system.
The components manufactured by this machine are very accurate in dimensional
tolerances.
CNC Router Machine:
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8. It works similarly as other CNC machines like lathe or Milling do.
The main difference is, it does all the carpenter work manually like such as door carvings,
interior and exterior decorations, wood panels, signboards, wooden frames, moldings,
musical instruments, furniture, and so on.
As per sketch, you can design if possible you can make into the system then execute on this
machine.
It provides a better surface finish.
This will be a very good machine in terms of the design of the door and more.
CNC Plasma Cutting Machine:
The Plasma cutting machine is defined as It is a process that cuts through electrically
conductive materials using an accelerated jet of hot plasma.
Whereas CNC Plasma cutting machine is defined as the cutting operation are done by a
computer numerically controlled system.
We studied CNC laser cutting above the main difference between them is, one operation
perform by laser which is very costly and whereas the other one is hot plasma which is less
costly and these are portables.
As the industry grows, new technology is invented these are one of them. Provide a better
surface finish.
5- axis machine:
It is a machine in which there is a total of 5 axes.
Initially, it was 3 axis (X, Y, and Z) the cutting operation of any instrument was done in the 3
direction but 2 additional axes added (A, B) which means there are total 5 axes, works are
cut are done in the 5 direction.
5 The Axis machine is used for making sculptures.
3-D Printer:
3D Printer is a CNC machine in which the metals are printed layer by layer. The 3D printer
works for the printing of buildings and complexes.
The design and drawing are made by the CAD and CAM process and then 3D Printer works
for visualizing that design.
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9. Pick and Place Machine:
This is another great type of machine. It is used in the industry. Let’s understand by a simple
example.
The company Amazon having a warehouse where it used to keep a large quantity of the
items. If the items are adjusted manually it takes a great time to avoid that this machine
introduces to pick and place the items.
Advantages of CNC Machine:
Following are the advantages of having a CNC machine:
1. The CNC Machine provides a workpiece with better precision and accuracy.
2. Fewer workers required which helps to saves the labor cost.
3. A high skilled operator not required. Even a trained worker can operate these CNC
machines.
4. CNC Machine can produce complex designs with high accuracy in minimum possible time.
5. CNC machine has an online editing program, which means any changes and mistakes in
cutting conditions or in dimension can easily be edited and modified by the part data store
in the computer without sending the tape for re-processing.
6. The conversion of the unit can easily be done by this machine (SI to British or from British
to SI).
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10. 7. It can diagnostic its own fault easily, there is a special software enables easy to
troubleshoot if the CNC system fails to operate and also having the capability to assist in
maintaining and repair the system automatically.
8. It also helps with safety reasons.
9. Low Maintenace required
10. Reduce setup-change over time.
11. The CNC Machine has Higher Production and capability.
12. It can run for 24 hours a day.
13. Reliable.
Disadvantages of CNC Machine:
Here are some disadvantages of CNC machine:
1. The installation cost is high.
2. Even do the parts of the CNC machine are high.
3. When any failure occurs in the machine the high skilled profession requires to solve the
issue.
4. Computer knowledge is required.
5. Program knowledge is required
Applications of CNC Machine:
These are some applications of CNC Machine:
1. The main application of the CNC machine is to remove metal at a faster rate as compared
to a traditional machine-like lathe, milling machine.
2. This is also used in fabrication industries.
3. This machine is used for automatic removal of metal from the workpiece wherein another
machine like lathe, Milling the metal remove is done manually.
Specifications of a CNC Machine:
Specification of a CNC machine can be categorized into these following points:
Machine specifications:
Centers height.
Distance between centers.
Swing diameter over the bed.
Swing diameter over the cross slide.
Transverse movement of the cross slide.
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11. Headstock specifications:
Hole in the headstock spindle.
Spindle end-use taper.
Tailstock specifications:
Spindle diameter.
Spindle end taper.
Sleeve travel.
Feed rate:
Rapid transverse.
Programmable feed rate.
Main Spindle specifications:
Speed range.
Output power.
Let Me Show You the Common Codes Used in CNC Programming:
CODE EXPLANATION OF CODE
N Sequence Number.
G Rapid Traverse.
X, Y, Z For tool motion about X, Y, Z direction (Linear Motion).
S Spindle Speed (Unit as per your setting).
F Feed Rate.
T Tool Number (i.e. Tool number 1 for facing or
turning).
M Miscellaneous Functions.
EOB End of Block (End of programme).
A, B, C For angular direction in X, Y, and Z direction.
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12. Difference between CNC and NC Machine:
At first, let me tell you about NC Machine, NC stand for numerical control, this is also an
automated machine but it can understand only either binary or numeric or in alphanumeric
programs.
An NC machine has
1. Software
2. MCU (Machine Control Unit)
3. Machine Tools
It doesn’t have a servo mechanism there for it has no feedback system also it has no
computer.
The program is typically stored in a tape with the help of special inserting device, the
modification or changes in the program is a tough job in the case of NC machine.
Now get a small idea by seeing these differences between NC and CNC.
NC MACHINE CNC MACHINE
NC stands the Numeric control machine. CNC stands Computer Numerically
Control Machine.
This is not software driven. This is software driven machine.
It can not imports CAD files. It can imports CAD file and convert into
part programming.
Operation parameter cannot be change. Operation parameter can be change.
It stores in Punch cards Memory. Directly stores in computer memory.
Machine cannot run continuously. This machine can run for 24 hours
continuously.
Less flexibility or Computational ability. CNC machine having High.
Takes more time for executing the
program.
This machine takes less time as
compared to NC machine.
High skill operator requires to operate NC
machines.
The semi-skilled operators can perform
the operation on a CNC machine.
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13. Less maintenance. High maintenance.
The maintenance cost is less. The maintenance cost is more.
Machining cost is less. Machining cost ismore.
Less Accuracy as compared to CNC
Machine.
Great accuracy.
Codes are Numeric, Symbol and letter
only.
Here the codes are G and M codes.
A single person can not perform several
operations on different NC Machines.
A single person can perform several
operation on different CNC machine.
There no feedback system. Feedback system are there.
Summary:
What is a CNC Machine?
CNC machine can be defined as the machine which is control by computer and the operation is
performed by feeding the program on it.
What Does CNC Mean?
CNC stands for Computer Numerical Control that means this machine tool is controlled by
the software of the computer. The programs are loaded in a computer through a keyboard
or tape and stored in the memory, which can be called whenever we need it.
What are the different types of CNC machines?
CNC machines are can be classified into the following types:
CNC laser cutting machine
CNC Lathe Machine
CNC Milling Machine
CNC router Machine
CNC Plasma Cutting Machine
5- axis machine
3-D Printer
Pick and Place Machine
What is the full form of CNC?
CNC stands for Computer Numerical Control.
What are the Different Parts of CNC machines?
A CNC Machine consists of following parts:
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14. Bed
Headstock
Tailstock
Tailstock quill
Footswitch or pedal
Chuck
Control panel
Tool turret
What are the Different Parts of the CNC system?
A CNC machine system consists of the following elements:
Program
Tape Reader
Mini-computer
Servo system
CNC machine tool
Conclusion:
As we already have seen that this type of system is software-based, the machine tools are
controlled by means of software. This system simplifies the usages of the conventional
machining processes.
Although nowadays you probably have seen at least one CNC machine in any industries it
lowers productivity as well. So it’s better to be a knowledgeable person in the space of the
CNC machine because this is the future of Manufacturing Technology.
Tada! A small quiz for you!
24
Created on October 27, 2019 By Saswata Baksi
Quiz on CNC machine
1 / 6
We use EOB
2 / 6
Binary or Numeric program is used for
3 / 6
In which type of machine, we use a mini-computer?
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15. 4 / 6
Which is better?
5 / 6
What is the full form of CNC?
6 / 6
What is full form of CNC?
Your score is
The average score is 72%
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So these are all about CNC machine, now I want to hear from you, ask me anything related
to this topic in the comment section, also you can participate in our discussion board here is
the link of that.
Also, we have lots of articles in the Mechanical Engineering topic, visit our homepage and
check out all those, maybe it will help you.
See you in any other articles cheers
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References:
CNC Machines and CNC Programming by NPTEL
Making CNC machine tools
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