Manufacturing is the process of making something, such as a physical object or a product, usually by giving shape to raw materials. It is done with the help of machines and tools.

CNC is a process that uses computers to automate a machine’s work. So with a CNC machine, human labor can be replaced with computer-controlled automation.

Today, CNC machines are used in many industries, such as aerospace, automotive, medical device manufacturing, and electronics assembly.

CNC manufacturing is the process of using Computer Numerical Control (CNC) to make parts. CNC manufacturing machines are controlled by a computer that sends instructions for cutting and other operations. The machine can be programmed to cut out a shape or design from a piece of raw material like wood, metal, stone, plastic, composites, etc.

This article discusses CNC manufacturing in detail by looking at its basics, applications, machine types, process, advantages, and disadvantages.

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CNC Manufacturing – Explained

What is CNC?

CNC is short for Computer Numerical Control. In CNC, manufacturing machines are programmed by machinists but controlled by computers.

These machines are known as CNC machines. Before introducing computers for controlling manufacturing machines, they were run through numerical control, which used hard-wired combinational logic units.

How does a CNC Machine Work?

In CNC machining, machinists make the toolpath for manufacturing a part and send it to machine control units (MCU) as program codes.

These MCUs are microcomputers, and they can understand the binary cutter location data from the code and implement it by moving the cutter location of the machine tool.

Applications of CNC Manufacturing

Subtractive Manufacturing

Subtractive or reductive manufacturing is the most popular CNC manufacturing technique, and it is used in a lot of applications.

Here a block of material is cut using machines to remove the material layer by layer until the desired shape is made.

The most common CNC machines used in subtractive manufacturing are CNC mills, routers, laser cutters, plasma cutters, lathes, waterjet cutters, grinders, EDMs, etc.

Some applications of subtractive manufacturing are woodworking, metal cutting, glass cutting, making tapped holes, drilling, turning, polishing, etc.

Subtractive manufacturing is employed on various materials like plastic, metals, wood, composites, stone, etc.

Additive Manufacturing

In additive manufacturing, the material is added layer by layer to make desired parts.

3D printers are popular additive manufacturing machines. Their major applications are in prototyping, medicine, jewelry, construction, aerospace, etc.

Compared to other CNC machines, 3D printers are capable of working with a limited set of materials.

Formative Manufacturing

In formative manufacturing, a workpiece’s shape is changed without adding or removing any material.

Here workpieces are pressed by applying high-pressure stress to change their shape. Forming machines like CNC tube benders, CNC press brakes, and CNC rollers are widely used in metal fabrication applications.

CNC Machining Process

CAD Operation – Designing

Before machining a part using CNC machines, a machinist must have the designs ready.

The designs are made in the CAD (computer-aided design) phase using different CAD software. Designs can be two-dimensional (2D) or three-dimensional (3D).

CAM Operation – Generating Part Programs

Once the designs are generated, they are processed by a CNC programmer using CAM (computer-aided manufacturing) software.

Some popular CAM software programs are CamBam, MeshCAM, EstlCAM, etc.

CAM software programs analyze the geometrical data of the design and make the necessary toolpath required for the machine to manufacture the part.

Later this toolpath information is fed to the machine as program codes.

Therefore, the programming of a CNC machine plays an important role in determining the quality of output, making CNC programming an excellent choice of career in the modern world.

Setting Up the Machine

Before running the program codes, the machinist will set up the machine with the proper workpiece and tools.

It includes clamping the workpiece, changing tools, refilling the coolant reservoir, editing parameters in the control software, etc.

Testing the materials beforehand is a good practice, and most machinists do this to customize the machine’s settings to optimize the job.

Running the Program

Once the machine is ready to run the job, the machinist provides the program code to the machine.

The machine implements the code by moving the workpiece or cutting tool.

In some advanced multiaxis CNC machining, such as 6-axis machining, the workpiece and cutting tools are moved simultaneously.

Post-Processing

Sometimes CNC machined parts may need further cleaning or polishing as these machined parts can have burrs, chips, and other debris which need to be removed before use.

Types of CNC Machines and Machine Tools

CNC Mills

CNC mills use a high-speed spindle to cut and remove material from a flat-surfaced workpiece. They are used for cutting metal, plastics, and other materials.

These machines use end mills made out of carbon steel, high-speed steel (HSS), and solid carbide.

CNC Lathes and Turning Centers

CNC lathes and turning centers work on cylindrical or conical-shaped workpieces. Here the workpiece is rotated or turned at high speeds while a cutting blade cuts it.

This process is often used to manufacture crankshafts, pistons, and gun barrels.

CNC Routers

CNC routers are mills that primarily work on plastic, foam, and wooden workpieces.

When comparing CNC mills and routers, CNC routers generally have a larger work area.

These machines are available in different configurations like desktop, 3018, 4-axis/rotary axis, compact, 5×10, 6040, etc.

CNC Drills and Vertical Machining Centers

CNC drills and vertical machining centers are used for drilling and tapping holes in a workpiece.

In these machines, the cutting tool only moves on the Z-axis. For moving the stock material, the workbed is motorized.

Laser Cutters and Engravers

As it’s clear from its name, laser cutters and engravers work on materials using a powerful laser beam.

They work best on thin sheets of material as the focus lenses used in these machines have a limited focal length.

When compared to CNC cutters, laser cutters are ideal for perfoming smooth cuts in thin materials while ensuring a quick cycle time.

CNC Plasma Cutters

CNC plasma cutters are just like laser cutters, but here a jet of hot plasma is used to cut through the material.

It is used to cut metal sheets and can only cut metals having good electrical conductivity.

CNC Waterjet Cutters

In CNC waterjets, water is pumped at high pressure to cut through a material. Generally, the pressure is above 50000 psi.

Sometimes abrasives are added to the water to cut on thick and hard materials.

Waterjet cutters can cut thicker materials compared to laser cutters and plasma cutters.

The ability to cut thicker materials with high precision comes at a higher price, and generally, waterjet cutters are more costly than laser cutters.

CNC Wire EDMs

Wire Electrical Discharge Machines (EDM) cut metal workpieces by melting and vaporizing them using an electro-thermal process.

Here the metal workpiece is cut by electrical sparks generated around a highly conductive wire.

CNC Tube Benders, Press Brakes, and Rollers

CNC tube benders, press brakes, and rollers are formative CNC manufacturing machines that apply stress to the workpiece and make it to the desired shape.

3D Printers

3D printers are the face of additive manufacturing in CNC. It is called 3D printing because it uses 3D computer graphics to make 3D objects.

These machines work by taking a digital file and turning it into an object by adding layer upon layer, one at a time. The layers are then built up until they form the desired shape.

3D printers can be used in many different ways and for many purposes, including industrial design, education, architecture, and medicine.

Role of CNC Machinists

CNC machinists have an important role in a CNC machine’s operation. They keep track of the machine’s work and perform required maintenance activities.

Also, CNC machines need to be programmed for their automated manufacturing process.

This needs an expert machinist to handle all the pre-machining processes like designing, generating the toolpath, executing the program, etc.

The main difference between a CNC machinist and a CNC operator lies in their experience to handle new machining processes.

Pros and Cons of CNC Manufacturing

CNC manufacturing machines are computer-controlled, meaning they are programmed to follow a set of instructions to machine a product.

This comes with some advantages and disadvantages. The disadvantages are mainly their high price and maintenance costs, but in the long run, they are profitable.

Pros	Cons
Reduced need for human labor	High maintenance cost
Reduced waste and rework	High initial cost
Reduced lead time
High precision and repeatability
Increased productivity

Frequently Asked Questions

What do CNC machines make?

CNC machines can make many different things. They are largely used in the manufacturing industry to create parts and pieces used in the production of a product. For example, furniture making, metal parts for automobiles, sporting goods, prototypes, etc.

What is a CNC used for?

CNC, also known as Computer Numerical Control, is used for machining and automation applications. Their primary application is in industrial machining but is also used in robotics and home automation.

What materials can be used in CNC machining?

In CNC machining, you can use metal and non-metal materials. Some popular metals used are aluminum, stainless steel, carbon steel, titanium, copper, etc. The most used non-metals are plastic, wood, foam, rubber, ceramics, and composites.