CNC Machine: Types Of CNC Machine, Parts, Application And Specifications [PDF]

Frankly speaking, we crossed the phase of a manually controlled machine. Do you feel that manually controlled traditional machines can cope with the latest demands and supply chain? No, not at all.

The industry is moving fast to adopt CNC machines. So it is wise to explore what is a CNC machine, what are the types of CNC machines, different parts, and specifications.

CNC is a generic term. Any machine which is controlled by a computer can be called a CNC machine. It is not restricted to any particular machine. At the end of this article, you will be getting a CNC machine PDF link to download this article for your future reference

You may see the following abbreviations in this article as you go forward.

• CNC- Computer Numeric Control
• NC-Numeric Control
• CAD- Computer Aided Design
• CAM- Computer Aided Manufacturing
• CAE- Computer Aided Engineering

What is a CNC machine

CNC ( Computer Numeric Control ) machine is a kind of machine which is controlled by a computer. For each and every operation you need to write a program and feed into it. Based on that program the machine will perform its job.

Like how we have different languages to write a software program, all CNC machine also has different logic and codes which can be read by both the machine and the computer. The programmer has to use those machines’ readable codes in the program so that the machine can understand that.

How CNC Machine Works: CNC Machine Working Principle

To understand how a CNC machine works, we need to know the three major subsystems that a CNC machine has. Those three major subsystems are the Command system, Drive/ motion system, and Feedback system. Below are the basic steps a CNC machine follows.

• Creating CAD models and export them to any neutral format
• Importing the CAD model and create tooling in CAM
• Create tooling program following standard CNC codes
• Export the code and feed it into the CNC control system
• CNC controllers read the data and prepare the machine
• The machine instructs the drive system to follows the path set by the program for tool movement
• Coolant, lubricants are injected as and when required as per the program
• Parts get manufactured and taken off from the machine

Creating 3D CAD models

The raw data for a CNC machine is the 3D CAD model. Nowadays any design starts with creating 3D CAD models. Many software like Creo, SolidWorks, Catia are well known for creating 3D models. 3D CAD models are the virtual mock-up of a part of a product

Creating CNC program in CAM

Once a CAD model is created, the data is sent to CAM software, CAM software reads the data, modifies the CAD data as per manufacturing guidelines, and creates programs for the CNC controllers.

That program directs a controller about what tool needs to be used, how the tool should move when the coolant should be applied and many other commands based on that particular part.

There are many codes like G Code, M codes which a CNC controller can read. These are standard codes that CAM software used to create programs. MasterCAM, EdgeCAM, SolidCAM are a few CAM software widely used in industries.

Export CNC program and Import it in the CNC Control System

Once the program is ready which was created by the CAM software, data is fed into the control system of CNC. Since those programs are created using standard CNC codes, machines can easily read those. Once machines read the data, it starts preparing the machine-like selecting the tool, selecting lubricants, etc, and other auxiliary operations.

Instruction to drive system to start and monitor operation

Once the machine is ready, it sends the instruction to the drive system to let the tool move in the direction as set by the program. The Drive system also controls the position and velocity of the tool movement. It also instructs the cooling system to inject coolant.

The feedback systems record all tool movement and operation. If there is a discrepancy, it will rectify the tool movement as per the program and inform the operator on the display unit. All CNC machine has an MCU ( Microcontroller Unit ) that monitor all these tasks.

Eject the part

Once the part is manufactured, machines compare the produced part with the data that was fed into the control system. If there are any differences, that will be popped up on the display screen and the operator can rectify the issue.

Types Of CNC Machine

Below are different types of CNC machines that are widely used in industries.

• CNC lathe machine
• CNC Milling machine
• CNC Plasma cutting machine
• CNC laser cutting machine
• CNC electric discharge machine
• CNC router machine
• CNC 3D Printer
• SPM ( Special purpose machine)

CNC Lathe Machine

We all know why we use Lathe Machines. We place the workpiece and the lathe moves around it to remove materials or create groves. The same principle is applicable to CNC lath Machines also. It also has the lathe at the center but its movement, rotation, and speed are controlled by computer input. Therefore it can produce precise and accurate parts with tight dimensional tolerance.

CNC Milling Machine

CNC milling machine is available in 3-axis or 6-axis configuration. The workpiece is placed into the machine and the tool moves to create a groove or cut in the workpiece. The movement and position of the tool are controlled by a computer in which you need to feed the program.

CNC Plasma Cutting machine

Like a CNC milling machine, CNC plasma cutting machine is also used to cut materials or create grooves. Instead of using a metal tool to cut the workpiece, it uses a plasma arc to cut through metals. Plasma arc can reach a temperature of up to 50K Fahrenheit. Plasma arc cutting machine can produce better parts compared to CNC milling machine

CNC laser cutting machine

CNC laser cutting uses CO2, neodymium (Nd) or yttrium-aluminum-garnet (Nd: YAG) lasers to cut through metals. Although operation wise it is similar to a CNC plasma cutting machine, the laser is not as strong as plasma. However, laser cutting machines offer high accuracy. CNC laser cutting is a very essential machine in industries nowadays.

CNC electric discharge machine

CNC electric discharge machine uses an electric spark to melt metals and reshape them. It can only melt certain areas of metals where it is exposed. That’s why CNC electric discharge machine is used to precisely manipulate a section of a workpiece by melting and reshaping it. The amount of electric spark and the spark movement are controlled by a computer.

CNC Router machine

CNC router machine does similar jobs like CNC milling or CNC lathe but the only difference is that they can create shapes in wood instead of metals. You can create door carvings, different shapes of wood panels, etc using this machine.

3D Printing Machine

The 3D printing machine is a Rapid Prototyping technique that creates an exact physical replica of a 3D CAD model. It uses multiple layers of materials joined together. A tool moves around to create those layers of material. The tool’s movement, position, and speed are controlled by a computer. I have a dedicated article on Rapid Prototyping. The link is given below for your reference.

Special Purpose Machine

Many industries build their own set of machines depending on their process and manufacturing. The reason is, no traditional machine suits their requirements. Mostly all SPM’s are CNC machines as they are controlled by a computer. They follow the same logic as a typical CNC machine

Key elements of a CNC machine

Below are the key elements of a CNC machine

• Program
• Input system
• Display
• Servo motors
• Machine tools
• Lubricant / Cooling system

Program

Program is the raw data for a CNC machine about what tool to use, how to move, at what speed it needs to move etc. It instructs the CNC machines on each and every operation that they need to perform.

Input System

Data from CAD software gets exported and then imported into the machine usually through a flash drive or direct network connection. Sometimes those data is fed into a separate computer which then signals the CNC. But in most cases, a CNC machine comes with an inbuilt computer where you can feed data.

Display

Displays are integrated or you need to connect a separate monitor. But in both cases display shows each and every operation of a CNC. It also shows if something is going wrong with the machine. The display system is the way an operator can interact visually with a CNC machine

Servo Motors

Servo motors are the main components of a CNC machine. They are the actual worker which moves the tool, positions the workpiece, transfer the parts, etc.

Machine tool

Machine tool does all those jobs that you want to see in the finished workpiece like removing materials, tempering materials, etc. The job of machine tools is similar to any traditional machine.

Lubricant System

The lubricant system helps to keep the system parts moving as without lubricant there will be excessive friction and the machine will break down.

Cooling system

All CNC machine has temperature sensors that sense high temperatures and automatically inject coolant. Unlike traditional machines where you need to apply coolant manually, the CNC machine is smart to apply coolant based on temperature.

Parts of CNC machine

Every CNC machine is different and will have a different set of parts. We will take the example of a CNC lathe and will explain what are the key parts are there in that machine.

• Headstock
• Bed
• Chuck
• Tailstock
• Tailstock quill
• Footswitch
• Tool turret
• Control panel

Headstock

The headstock has the main motor of the unit which drives the main spindle. The chuck is mounted on the main spindle

Bed

The platform on which the tool turret travel is the machine bed

Chuck

Chuck is the key component that holds the workpiece. Chuck has jaws that you can tighten or loosen to grip the workpiece

Tailstock

Tailstock provides the extra gripping for machining of long components. Although the chuck holds the workpiece in long components the machine needs extra support to keep it straight.

Tailstock quill

Like headstock, a tailstock is a unit that moves back and forth as per the workpiece length. But tailstock quill is the actual component that grips the workpiece. Tailstock quill is housed into the tailstock

Foot Switch

The footswitch is used to adjust the chuck and tailstock. Through the footswitch, the operator opens or closes the chuck to grip the component. Similarly, it actuates the forward or backward motion of the tailstock quill

Tool Turret

Tool turret holds the tool that is required to perform the job. Depending on the tools the turrets are also different.

Control Panel

This is the only window through which you can start the machine, stop the machine, load the program, run the tool, inject coolant, and all other required jobs of a CNC machine. This is the eye of the CNC machine through which you can see what’s going on in that machine.

Specification of CNC machine

As you know that every machine is different. So specifications of every machine will also be different. Right? But for example, I will show the specification of a CNC lathe machine so that you get a brief idea of a CNC machine

Specification of CNC machine can be categorized as follows

• Capacity
• Spindle
• Axes
• Tooling
• Tailstock
• Coolant system
• Lubricant system
• Hydraulic system
• CAD compatibility

Capacity

• Distance between center
• Swing over bed
• Swing over carriage
• Maximum turning diameter
• Maximum turning length

Spindle

• Spindle size
• Spindle speed
• Spindle power
• Bar capacity
• Bore through spindle
• Chuck size

Axes

• X-axis stroke
• X-axis rapid
• X-axis guideways
• Z-axis stroke
• Z-axis rapid
• Z-axis guideways

Tooling

• Number of stations
• Turret type
• Turning tool size

Tailstock

• Tailstock quill diameter
• Tailstock quill taper
• Tailstock travel range

Coolant

• Types of coolant
• Coolant tank capacity

Lubricant

• Lubricant type
• Lubricant tank capacity

Hydraulic

• Hydraulic pump capacity

CAD compatibility

• Easy interface for CAD data transfer
• CAD file format support
• Feature recognization
• DXF support

Block Diagram of CNC Machine

What is a NC machine?

NC machine is the abbreviation of numeric control machine. The term says it all. It is a machine where you have to feed the numeric value of parameters and the machine will do the job for you. Ideally, nowadays all machines are numeric control.

NC machine does not have a display system or control system to run the machine. It does not have a feedback system as well. Typically data is fed manually using an inbuilt input system. NC machines are way too less efficient than a CNC machine

Difference between NC and CNC machines

Below are the basic differences between NC and CNC machines.

What is CNC programming ?

CNC programming is the heart of a CNC machine. It has a set of codes and instructions to instruct the machine about which tools to use, where to move, and many other functions. Machines can decode those codes and follow the instruction a create parts. It’s a language that both machines and computers can understand.

What Is G-Code in CNC Programming?

G-Code is a proprietary standard established by the Electronics Industry Association ( EIA) in 1960. It was introduced so that all CNC machines follow the same standard. The goal of G-Code is to streamline and standardize CNC programming across the globe.

For example, we use C-Programming language to create many CAD software. Similarly, G codes are used for CNC programming. Below are the activities that the G Code does.

• Start the CNC program
• Choose the tool
• Move the tool
• Turn on spindle and coolant
• Start the machining
• Turn off the spindle and coolant
• Keep the produced part in a safe location
• End the CNC program

Common codes used in CNC Programming

Advantages of a CNC machine

• Complex parts can be produced at a very short cycle time
• More precise and accurate parts are possible.
• The lead time for product development gets reduced.
• Any error in the part can easily be rectified.
• Easy troubleshooting is possible as every error gets displayed.
• Radar-based safety warning safeguards workers from any accidents.
• The part cost gets reduced due to cycle time reduction
• Less chance of error or defects in the part
• Maintenance and change of tools are easy
• The machine can run without a worker. So it can run 24 hours a day.
• CNC machine increases output and productivity

Disadvantages of CNC machine

• High initial setup cost
• Expensive tooling
• Maintenance is highly expensive
• Computer knowledge is required for the operator
• The license cost of CAD and CAM software is high
• Dedicated programmer required for CNC programming
• The high lead time of repair for machine breakdown.

Conclusion

No doubt, CNC machines are the future. I personally did not see any industry which does not use CNC machines. The reason is very simple, CNC machines increase productivity and that’s the market demand now. If you want to stay in business you have to be fast and efficient and CNC machines help to speed up production

I hope I could able to give you a clear picture of a CNC machine. Every CNC machines are different and use different technologies. Covering details of every CNC machine is out of the scope of this article. But I believe you may have a lot of questions regarding CNC machines. If yes, please do write in the comment section and I will be happy to assist.

Frequently Asked Questions ( FAQ)