Difference Between NC, CNC, and DNC

Feature NC CNC DNC

Input Method Punch Tape Computer System Computer System
Number of machines under each
1 1 Multiple machines
control system
Ability to modify an existing
Low High Very High
program
Machine feedback from the tool No Yes Yes
Low-volume Low and medium volume High volume
Application
production production production
The various differences between NC and CNC machines in tabular form are as follows:

Sr. No. NC CNC

It is defined as a machine that is controlled by It is defined as the machine that is used to control
a set of instructions in the form of numbers, the speed of the workpiece and tool with the help
1
letters, and symbols. The group of instructions of programs prepared in the computer. The
is called a program. program is written in alphanumeric data.
Description: NC is a machine controlled by a Description: CNC is a machine that is used to
2 set of instructions in the form of numbers, control the speed of the workpiece and tool with
letters, and symbols. the help of a program designed in the computer.
Nature: NC is a hardware-based type of
3 Nature: CNC is a software-based system.
system.
Program: Programs are fed directly into the
Program: The program is fed into a media
4 computer by a small keyboard similar to our
tape/punch card.
traditional keyboard.
Operation: It is not possible to run the NC
5 Operation: It can be run all day (24 hours).
machine continuously.
Accuracy: Products developed by CNC machines
Accuracy: NC machine has lower accuracy as
6 are high-quality products with high precision and
compared to the CNC machine.
accuracy rates.
7 Program modification is difficult. Modifications to the program are very easy.
The cost of an NC machine is less than that of The cost of a CNC machine is higher than that of
8
a CNC machine. an NC machine.
Flexibility: NC machines provide less Flexibility: The NC machine provides additional
9
flexibility and computational capability. flexibility and computational capability.
NC machine has lower maintenance cost as The maintenance cost of a CNC machine is
10
compared to CNC machine. higher than that of an NC machine.
Skills: A semi-skilled operator can run a CNC
Skills: The operation of NC machines requires machine. The main requirement is that the
11
a highly skilled operator. operator should have basic knowledge of
computer systems.
Working: It works on XY and straight-line
12 Working: It works on the X-Y-Z axis.
axis.
Execution time: The execution of the work takes
13 This requires more time to execute a task.
very little time.
14 Storage of programs: Programs cannot be Storage of programs: Programs can be stored in a
 stored in NC machines. computer and used repeatedly.
Once indexed, the operation parameters cannot
15 Operation parameters can be easily changed.
be changed.
This provides less flexibility and This provides additional flexibility and
16
computational capability. computational capability.
In CNC machines, programs are fed directly into
In NC machines, the program is fed into a
17 the computer by a small keyboard similar to our
punch card.
traditional keyboard.

What is computer numerical control (CNC)?

Computer numerical control (CNC) is a manufacturing method that automates the control,
movement and precision of machine tools through the use of preprogrammed computer software,
which is embedded inside the tools.
CNC is commonly used in manufacturing for machining metal and plastic parts. Mills, lathes,
routers, drills, grinders, water jets and lasers are common cutting tools whose operations can also be
automated with CNC. It can also be used to control nonmachine tools, such as welding, electronic
assembly and filament-winding machines.

How computer numerical control works

With CNC, each object to be manufactured gets a custom computer program, usually written in an
international standard language called G-code, stored in and executed by the machine control unit
(MCU), a microcomputer attached to the machine. The M-code language is also used in conjunction
with G-code in CNC operations.
While G-code controls the movement and functioning of the machine, M-code controls the
operation's external movements. The program also contains the instructions and parameters the
machine tool follows, such as the feed rate of materials and the positioning and speed of the tool's
components.
Early in the process, engineers create a computer-aided design (CAD) drawing of the part to be
manufactured and then translate the drawing into G-code. The program is loaded onto the MCU,
and a machine operator performs a test run without the raw material in place to ensure proper
positioning and performance. This step is important because incorrect speed or positioning can
damage both the machine and the part.
When everything is ready, the CNC machine runs its program and completes jobs with precision as
instructed. The jobs could involve anything from creating something from scratch to cutting a
workpiece or printing anything.

Why is computer numerical control important?

Numerical control enables machines to produce items more quickly and with better surface finishes
without the need for manual machining or extensive human participation.
The following are some benefits of CNC systems:
 • Cost reduction. CNC machines are cost-effective and bring down the cost of production
due to precision manufacturing. Energy consumption is decreased as a result of increased
production efficiency, scalability and less material waste, which also lowers operating
expenses. The weight of potential financial obligations related to worker safety is also
lessened, which helps with cost-cutting.
• Waste reduction. The software used to run various kinds of CNC machines results in little
to no waste during the manufacturing process due to simulations and repeated optimizations.
• Improved worker safety. CNC machines minimize the chance of accidents and guarantee
worker safety because there is less need for human interaction. Most modern CNC machines
are self-sufficient and can be handled remotely by people for software upgrades, design
changes or other preventative maintenance.
• Human error reduction. Since human error is eliminated in the manufacturing process with
CNC, it is thought to offer greater precision, complexity, speed, flexibility and repeatability.
This ultimately results in fewer defects in the manufactured products.
• Contour machining. CNC provides capabilities such as contour machining, which enables
milling of contoured shapes, including those produced in 3D printing and designs.
• Faster MCU programming. Some CNC systems are integrated with CAD software and
computer-aided manufacturing software, which can speed the process of programming the
MCU.
• Improved operational intelligence. Integration with enterprise resource planning software
and related applications, such as enterprise asset management software, can facilitate
operational and business intelligence processes and help improve plant performance and
maintenance.
• No bottlenecks. With the higher level of automation used, CNC systems reduce production
and manufacturing bottlenecks and improve the outcome.
Along with the wonderful benefits that CNC machines offer, they do tend to be more expensive,
require more maintenance than other production methods and compel companies to hire a skilled
CNC programmer.