What is CNC Machining – The Ultimate Guide

What is CNC Machining – The Ultimate Guide

‘What is CNC machining process?’ is a common question people ask regarding industrial manufacturing processes.

CNC machining is nothing short of a marvel of the modern world. It has made it possible to create objects at ten and even a hundred times the speed that was present a few decades ago.

Due to the vast application of CNC machining, it becomes vital to have an in-depth understanding of the process and how it works.

That is exactly what we will cover in this article. You will know all about what CNC machining is, how it is done, its different types, and the benefits that the process encompasses.

What is CNC Machining?

What is CNC Machining

CNC machining is a subtractive manufacturing process where an object is shaped by removing material from a workpiece. The process is done by dedicated machine tools and controlled by CNC.

CNC stands for Computer Numerical Control. It means utilizing computerized software to control how a machine moves and operates.

CNC machining works on a wide variety of parts, such as metals, metal alloys, wood, stone, and more. The size of machine tools can vary, based on the scale of the part that requires manufacturing.

Who Invented CNC Machining?

Removing material to shape an object has been an ongoing practice since ancient times. The process to control the machine tools through numerical control was invented in 1949 by John Parsons at MIT.

Development of CNC Machining

In 1949, MIT carried out a research project for the US air force to use motorized methods for creating helicopter blades and aircraft engines and frames. This is what gave rise to CNC technology.

Richard Kegg, in 1952, further improved the numerical control machining process which led to the development of CNC milling machines.

Due to the absence of computers, the automated nature of early CNC machining processes was made possible with the help of punched tape. With the development of digital computing in the 1960s, punched tape was replaced with computerized controls.

How Does CNC Machining Work?

CNC machining relies on computer programs to create the layout of the process in which the machine tool should function. Since users cannot directly communicate with the machine tools, software called Computer Aided Design (CAD) is used.

CAD software creates the 2-dimensional and 3-dimensional models for the required final part. With this design, the machine knows what the final part looks like.

The computerized controls do the calculation required for removing material so the workpiece looks like the final part created in the CAD software.

Let us go through the breakdown of various processes that occur during CNC machining:

The Four Stages of CNC Machining

CNC machining occurs in four stages that happen in the order as follows:

Stage 1: Creating the CAD Model

To start with CNC machining, firstly the 2D or 3D model of the final design is required. This model is created in CAD software. There are many CAD software available online, both free and paid ones.

Creating CAD models is not difficult and can be learned easily. However, some complex parts might require more experience with CAD, for which CAD model designers can be hired.

Stage 2: Converting CAD Model to CNC File

No CNC machine understands CAD language directly. Machines only recognize movement based on coordinates. Therefore, we need to convert the CAD model to a CNC understandable file called G code.

Many CAD software can write the output file directly in the G-code by using the particular setting during saving the file.

In other cases, converting the CAD design to a G code will require a dedicated software called Computer Aided Manufacturing (CAM). CAM software is a very functional tool when it comes to the automation of machine processes.

Besides using CAM software, there are many simple free tools that can convert simple CAD designs to G code with the click of a button. However, they don’t have the vast suite of features that CAM software offers.

Stage 3: Configuring the CNC Machine

Before starting with the manufacturing processes, you need to set up the CNC machine the right way.

Think of this as configuring the printer before you print something. You need to feed the printer with pages and check on a couple of settings. CNC machines operate in a similar way.

Before you start with the machining, there are many setup processes you need to go through. For instance, you need to make sure that the workpiece is placed properly on the machine. The dies need to be positioned correctly, and you have to check on other position settings as well.

Stage 4: Executing the Machine Operation

Once the configuration stage is complete, the machine operation can begin. For this, you can execute the program on the display panel of the CNC machine.

Depending on what you are designing, you might have to go through various program prompts to choose different types of settings and options.

Once the program is executed, the machine keeps on going till the end of the program. It will only stop if it is stopped by the operator, in case of some unexpected error, or in case of power disruption.

Terminologies in CNC Machining

Terminologies in CNC Machining

If you want to be familiar with CNC machining, it is crucial to get acquainted with all the terms used in this field. Some of these terms that you will commonly encounter are:

Computer-Aided Design (CAD)

Computer Aided Design is the software that creates the graphic representation of the required final part in 2D or 3D. Generally, complex parts are created by breaking them into small parts, each having its own CAD models.

AutoCAD and FreeCAD are two of the most popular CAD applications, with the latter being completely free.

Computer-Aided Manufacturing (CAM)

Computer Aided Manufacturing (CAM) software is used for creating programs that a machine can understand. These programs help in the automation of different types of machines, including CNC machines.

CAM software works together with CAD program for operation execution of CNC machine. Most quality CNC machines will come with complimentary CAM software for you to use.

Distributed Numerical Control (DNC)

In a Distributed Numerical Control (DNC), multiple machine tools can be connected to a central server. The central server processes the design files and sends commands to each of the machine tools separately.

DNC is utilized in case the individual CNC machine memory is too small to process the software by itself. It can also be utilized where multiple numerical control machines require synchronized working for faster operational capabilities.

Manufacturing Data Collection (MDC)

Manufacturing Data Collection (MDC) is exactly what it sounds like. Manufacturing Data Collection software collects data from machines and operators about the different manufacturing information generated in real-time.

This information helps the manufacturers to improvise on the existing production line. It also points out the causes of any delays and production loss.

What are G-code and M-code?

The G-code and M-code are files that a CNC machine requires to operate. Each of these has its own importance, which we will go through one by one:

G-code

The ‘G’ in G-code refers to Geometry, making G-code a Geometric code. The G-code is an alphanumeric command that tells the CNC machine how to move.

The X, Y, and Z alphabets in the G-code mainly refer to the axes of movement and the number pertains to the value in that particular axis. N refers to the line number.

Some particular codes refer to special operational capabilities of the machine, such as adjusting the spindle speed or turning the spindle on and off.

M-Code

M-codes are miscellaneous machine code that perform the non-cutting actions of the CNC machine. This includes things like starting and stopping different programs, controlling the coolant flow, or adjusting the behavior of different tools.

What are the Different Types of CNC Machining Processes?

A CNC machine is not a particular machine as it is a group of a lot of different machines working on different machining processes. Some common CNC machining operations are:

CNC Milling

CNC milling is one of the most popular types of CNC machining processes. In fact, many professionals often use CNC machining and CNC milling interchangeably.

In a CNC milling machine, there are rotating cutting tools that move relative to the workpiece to remove the materials.

The cutting tool (also called the milling tool) is fixed on a spindle that can rotate. The rotation and movement of the spindle can give CNC milling machines the ability to perform three or more axes machining.

CNC Turning

In CNC turning, a bar of the workpiece material is pivoted on a chuck and rotated. The cutting tool is then fed to the workpiece, removing materials at a very high speed.

CNC turning can lead to a very fast production process. However, a lot of material is removed and wasted in the CNC turning process.

CNC Drilling

CNC drilling process is a lot simpler than milling tools and the turning process. In CNC drilling, the workpiece is held stationary while a drill bit moves over the workpiece and creates holes.

The purpose of the drill holes can be for adding screw bolts, for aesthetic requirements, or any other use.

CNC Grinding

CNC Grinding

CNC grinding machines make use of a rotating flat abrasive wheel for removing the material on the rough surfaces of a workpiece. This machine process is usually applied for creating a smooth finished part. The wheel rotates at a very high speed for this purpose.

CNC Routing

CNC routing is very similar to CNC milling. The main difference that puts them apart is that in routing, the workpiece is always stationary and the cutting tool moves in X, Y, and Z dimensions. CNC routing creates faster cuts as compared to milling, while compromising the accuracy and design complexity.

Other Types of CNC Machines and CNC Operations

Besides the various types mentioned above, there are other CNC processes as well. There are also some independent fabrication machines that are integrated with a CNC for automated movement. Some of these additional CNC machines are:

Broaching

Broaching utilizes a toothed cutting head to create niche shapes on a workpiece. Broaching cuts are very consistent and highly accurate. These machines can be linear or rotary (with a rotating toothed cutting tool).

Sawing

Sawing utilizes a toothed blade for creating straight, linear cuts. The cuts are created by removal of material due to friction with the blade. When operated with a CNC, this process is usually applied for the automated cutting of wood.

Honing

Honing is a process similar to grinding, in the sense that it is generally used for the secondary finishing of the material. In the honing process, an abrasive stone or wheel is used for controlled grinding of the workpiece for creating the desired shape, size, or finishing.

Lapping

Lapping is also similar to grinding. However, instead of using a grinding wheel to create the smooth surface finish, lapping makes use of an abrasive paste, powder, or mixture. This abrasive mixture is inserted between two materials (at least one of which is the workpiece), and these two materials are then rubbed against each other.

lathes

CNC lathes are primary shaping processes used for machining of metals or wood. In a lathe machine, the workpiece is rotated around a central axis and the machining head moves linearly along the surface. CNC lathes can perform a variety of functions such as cutting, drilling, sanding, knurling, facing, and more.

Plasma Cutters

Plasma cutters are an evolved form of the cutting technology, making use of a high temperature jet of plasma to cut through a material. The plasma is created by an electrical arc, so this method applies to conductive materials only.

Laser Cutters

Laser cutters are another one of the modern manufacturing processes. They use a laser beam to cut through any material. Unlike plasma cutting, laser cutting is not limited to cutting of electrical conductive materials. Laser beams can cut through anything by adjusting the laser parameters.

Flame Cutters

 

Flame Cutters

Flame cutting uses an Oxy-acetylene (also known as Oxy-fuel) gaseous mixture to cut through metals. When this Oxy fuel beam is narrowed and ignited, it creates an ultra high temperature flame that can cut through metals very easily.

Press Brakes

The purpose of Press Brakes is to bend metal plates and sheets. The material is placed between a V-shape or U-shape die and the die is then pressed on the material. This creates the bend as required.

Electric Discharge Machines (EDM)

Electrical Discharge Machines (EDM) is used for the cutting of conductive materials. In EDM, electrical pulses are let out by a cutting head near the material, creating an electrical arc. This arc melts and removes the material at the required position resulting in a cut.

Water Jet Cutters

Waterjet cutters utilize ultra high-pressure water for the cutting action. These cutters can cut through anything, be it metals, alloys, wood, stones, or even glass. The water jet beam is controlled by a CNC and moved according to the software.

What are the Benefits of CNC Machining?

CNC machining is often considered a modern boon due to the numerous advantages it offers. While we have a detailed article covering the benefits of CNC machining, let us have a brief overview of some of these advantages:

  1. Production Speed – Production speed is one of the primary reasons which led to the vast and rapid spread of CNC machining. With CNC machining, it is possible to speed up production exponentially since it removes the limitations that human labor brings.
  2. Consistency – Computer Numerical Control machining makes sure that all the parts created look and work the same. There is no possibility of human error. This leads to the creation of precise objects that serve their purpose exactly as intended.
  3. Reduction of Rejections – In the conventional manufacturing processes using manual labor, there was a lot of human error which led to rejections during quality control. This creates a lot of wastage of time and resources. With CNC machining, the whole process is automated which leads to minimal rejections.
  4. Cost Saving – Labor costs include not only the salary paid to the labor but also the downtimes during breaks and the added benefits payments. With CNC machines, you eliminate all of these payments, leading to huge savings in the costs. However, keep in mind other important factors that affect cnc machining costs like quantity, material selection, and geometry.
  5. Manufacturing Data Tracking – CNC machines allow manufacturers to track the entire manufacturing process for every part. They can learn about the exact machines through which every part went during the manufacturing process. In case of a fault, the exact cause can be tracked immediately.
  6. Accuracy – With CNC machining, it is possible to accuracy on a micro level. Manufacturers can even push that limit with appropriate tools. Such type of accuracy is not possible with manual machining operations.

Cost Saving

What Materials Can Be Processed By CNC Machines?

As an extremely versatile technology, you can choose from a wide range of CNC machining materials. In fact, you do not even need different CNC machines for different materials. Most machines support multiple materials, and you can switch between the materials with a slight change of tooling.

Metals

Metal parts are one of the most common materials that undergo the CNC machining process. Metals have high hardness, so using manual machining can be long, arduous, and less precise. CNC machines provide the best and fastest way to work on metals.

Some of the metals that are used to manufacture parts with CNC machines are:

  • Aluminum: Aluminum is not just the most abundant metal on earth, it is also the most common metal for CNC machining. Its high strength-to-weight ratio makes it ideal for lightweight parts that require decent strength.
  • Magnesium: CNC Magnesium is most commonly utilized for creating the outer body of electronics. This is because Magnesium is 33% lighter than Aluminum, making it perfect for reducing the weight of electronics like laptops.
  • Titanium: Titanium is one of the toughest metals out there. It undergoes CNC machining for applications like aerospace, military, and any other high-grade requirement.
  • Cast Iron: CNC machining cast iron is very useful as it can produce parts at twice the speed of steel, with more wear resistance of tools.

Alloys

CNC machines can work on metal alloys just as well as metals. Here are the common alloys that go through CNC machining:

  • Stainless Steel: Stainless Steel is one of the more popular varieties of steel. Due to its hardness and other physical properties, it is always shaped by the CNC machining process.
  • Carbon Steel: Carbon steel is the most widely used alloy in the world. While it is cheaper than stainless steel, it has higher strength. CNC machines can shape carbon steel with high accuracy.
  • Brass: Brass is soft and corrosion resistant. There are many varieties of brass, with varying proportions of zinc and copper. All these varieties can be CNC machined.

Plastic

Many people are unaware of it, but CNC machining also applies to shape plastic parts too. These plastics include:

  • Nylon: Nylon is strong, flexible, and fire resistant. CNC machined parts of Nylon are used to replace any metal parts since Nylon also has good lubrication properties.
  • ABS: ABS plastics are often used for applications like injection molding due to their thermoplastic nature. However, when it comes to making prototypes, CNC machining of ABS is the better way to go.
  • PMAA: PMAA Acrylic is a strong plastic and transparent in nature. Therefore, CNC PMAA applies for replacing the glass with plastics, such as optical equipment or food containers.
  • PEEK: PEEK Is one of the most expensive varieties of plastics out there, with exceptional temperature resistance and physical properties. CNC machining of PEEK finds applications in aerospace and medical areas.

Wood

Wood is another common material for CNC machining. Not only that, it is actually quite easy to CNC machine due to its soft nature. The most common application of CNC machining of wood is for making furniture.

What are the Applications of CNC Machining?

CNC machining has applications in each and every industry, from the creation of tools to the final end product itself.

Let us have an overview of some of the use cases of CNC machining process:

  • Vehicles: CNC machining is utilized for making the frames, engines, and other small components of all types of transport vehicles. This includes cars, trains, and even airplanes.
  • Metal Fabrication: The metal fabrication industry relies on CNC machining for every type of project. The variety of CNC machines is so vast that it is always used in one form or the other.
  • Electronics: Lately, the electronics industry is also incorporating the use of CNC machining for making frames for appliances.
  • Research and Development: Since CNC machining can create anything based on a 2D or 3D digital model, it is the go-to method for making prototypes.
  • Defense: High-end CNC machines are used for heavy-duty operations in defense, such as the creation of weapons, aircraft, and more.
  • Architecture: CNC machining is also used for creating art and decor pieces. For instance, the intricate stonework you see in kitchens is made using CNC-controlled waterjet cutting tools.

How Does CNC Machining Compare to Other Machining Methods?

If you were to seek an alternative to CNC machining, the only thing that can come up is manual machining, i.e. machining done by hand. Of course, CNC machining is leaps and bounds ahead of this machining method, so much that there is not even a debate or a question.

Some of the points to consider about CNC machining vs Manual machining are:

  • Industries nowadays follow the large-scale manufacturing process suitable to meet the large scale demand. With CNC machining, this demand can be fulfilled effectively while manual machining cannot produce parts at the required production rate.
  • By using CNC machines on tasks that require only physical labor, human workforce can be dedicated to much more crucial and intellectual tasks.
  • CNC machines eliminate the human error factor that is present in manual machining. This leads to better utilization of resources by lowering the defective pieces.
  • There are many tasks that manual machining cannot accomplish due to physical human foundations, such as working on extremely high hardness materials. CNC machining can complete them with ease.
  • With CNC machining, there is no downtime due to lunch breaks or shift changes. Additionally, production can run 24×7, which further increases the production rate by a huge factor.

Are CNC Machines Hard to Operate?

Are CNC Machines Hard to Operate

Every type of CNC machine has its own operation. In general, CNC machines are easy to operate and you do not require any technical course to use one.

In fact, you can create basic parts after a few hours of tutorial videos, which are abundant online.

If you want to be a pro at CNC machining, you can spend some time learning the designing part to create the CAD drawings. Once one knows how to create the technical drawings and write an efficient digital programming code, they can even optimize the existing manufacturing process used by a CNC machine.

Is CNC a Good Career?

Yes, CNC is an amazing career not only in terms of monetary remuneration but also in terms of job experience. CNC operators get to use their minds on real-world problem solving to create productive and innovative equipment every day.

Is CNC in High Demand?

Since CNC machines have taken over the manufacturing process for each and every sector, CNC operators are indeed in huge demand nowadays.

CNC Machining Market Overview

The CNC machining market is expected to reach a valuation of over $128 billion by 2028, according to a Fortune report. The major driving factor in this growth rate is going to be the increased demand for semiconductors, use of CNC for making medical equipment, and the rise of EV vehicles.

Challenges in the CNC Industry

The CNC industry has established a dominance that isn’t going to fade in the next few decades or so, until a new technological revolution comes along. Even so, there are a couple for challenges in the industry that can be problematic to some.

For one thing, CNC machining is not very customization friendly. It is possible to create custom pieces, but it requires going through the whole process all over again. For making slight changes to the final pieces, one has to make alterations to the CAD files in the first stage.

Another challenge comes when we talk about making complex parts. There are machines available now that have the additional axes required to make complex parts, but many manufacturers are using CNC machines where the freedom of movement is limited.

Phasing out the old machines to incorporate the new, high-end CNC machines with better features can be challenging.

What are the Trends in the CNC Machining Industry?

The major trends that are ongoing in the CNC industry in the present timeline are:

  • Development of more axes to create the most complex geometries possible
  • Increased use of robotics to possibly make the entire process automated
  • Developments in CAD and CAM programming language for utilization of newer features
  • Increased workability on the nanoscale for use in semiconductor applications

Endnotes

CNC machining is the basic pillar on which modern technology stands. The CNC machining process begins with the most basic raw materials, turning them into anything the mind wishes.

The technology is so amazing and powerful that it even turns metal sheets into aircraft and automobile frames and metal bars into the axles that run those automobiles.

CNC machine tools are the go-to option, whether you require prototypes, small-scale sample production, or large-scale production runs.

The best thing is that you don’t even have to own any CNC machining equipment to make use of the benefits of the process.

You can use third-party CNC machining service providers such as 3ERP to get anything manufactured with the most high-end CNC machines, paying only the production cost.

Get in touch with us to know more.

 


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