What is CNC Machining: Advantages, Processes & Materials

In the 21st century, industrial automation has led to incredible technological advancements in manufacturing, primarily built upon the use of precision machinery.

CNC machining is a common manufacturing process known for its high precision, accuracy, and ability to design complex products. Machined products are widely used across various industries. This article will discuss the basic knowledge of CNC machining, the process, advantages, materials, and applications.

What is CNC Machining?

CNC, Computer Numerical Control, refers to a subtractive manufacturing process that uses numerically controlled machining tools. CNC machines use G-code and M-code derived from CAD models to control the movement of the machine, tools, and workpiece, removing material from a blank or workpiece to produce various parts.

CNC machining is an automated process with many advantages and is compatible with numerous metals, plastics, and composites. It is often used to manufacture complex shapes and high-precision parts, widely applied in industries such as aerospace, automotive, medical devices, and electronics. Compared to processes like 3D printing (additive) and injection molding, CNC machining requires tight tolerances. Let's continue reading to learn more.

How Does CNC Machining Work?

The foundation of CNC machining is a programming language that includes instructions. Each CNC machine has a corresponding computer system that requires CAM software to convert the 2D or 3D models created by CAD into a set of instructions (G-code) for the CNC machine to follow in order to create the final part. Once the machine starts running, the process does not require any manual intervention except for loading materials, unloading the final part, or repositioning the tool or workpiece, which greatly reduces human error.

Next, let's look at the four main stages in the CNC machining process.

1. Creating the CAD Model

Before starting CNC machining, a 2D or 3D model needs to be created using CAD (Computer-Aided Design) software. Creating a CAD model is not difficult, but designing complex products requires skilled and professional designers. According to the requirements and functions of the product, designers use CAD software to create the design, including the shape, dimensions, materials, and other specifications of the part.

2. Converting CAD to CAM

CNC machines do not understand the digital design data from CAD files, so the CAD files need to be exported to CAM (Computer-Aided Manufacturing) software. CAM software has a set of tools that can convert the CAD design into G-code, which the CNC machine can read.

3. Configuring the CNC Machine

Before manufacturing, it is essential to select the correct CNC machine and perform proper setup. Setting up the machine includes calibrating the zero point, installing the appropriate tools, setting cutting parameters (such as spindle speed, feed rate, etc.), and testing the program run. Ensuring everything is set up correctly helps avoid errors during the machining process.

4. Machining Execution

Once the configuration is complete, the operator can continue to perform the operation through the display panel on the CNC machine. Once the start button is pressed, the machine will select the appropriate tool and move to the workpiece to perform the cutting task as indicated by the G-code until it runs to the end of the program.

A Brief History of CNC Machining

In the mid-20th century, with the development of electronic technology, the use of manual or manually operated machines to manufacture parts no longer meets the need for mass production of high-precision complex shapes.

In 1948, John Parsons was commissioned by the U.S. Air Force to design the first CNC machine, and in 1952, MIT and Parsons collaborated to successfully develop the first demonstration machine.

With the development of computer technology, in 1969, the first CNC machine with computer control was born, and since then CNC machining has entered a new era. 1980s, the combination of CAD/CAM technology and CNC machining has greatly improved machining efficiency and accuracy.

If you want to learn more about CAD and CAM, please continue reading below.

List of Terms Used in CNC Machining

CAD-Computer Aided Design

CAD, known as Computer-Aided Design, is a method that uses computer technology for design and drafting. It allows the creation of 2D and 3D drawings of the parts to be machined, improving design precision and efficiency. Common software includes AutoCAD (2D and 3D), Inventor (3D), SolidWorks (3D), and Creo (3D).

CAM-Computer Aided Manufacturing

CAM, or Computer-Aided Manufacturing, converts 2D drawings or 3D models created in CAD software into instructions that can be understood and executed by a machine, with the converted file being a collection of G-code and M-code instructions.

Best examples include Fusion 360, SolidCAM, and Mastercam.

What are G-code and M-code?

G-code and M-code are the core languages of CNC machining, used to control machine movements and auxiliary functions. The correct use of these codes directly impacts the precision, efficiency, and safety of the machining process.

G-code

Responsible for controlling the movement of the machine, such as path selection, speed setting, and performing fine machining. In G-code, "G" stands for geometry, and the X, Y, and Z references in G-code refer to the axes of movement. The numbers correspond to specific values for each axis. "N" refers to the line number. G-code is geometric code used to instruct the cutting tool how to move.

M-code

Manages the auxiliary functions of the machine, such as starting the lubrication system, cooling, and tool changes. M-code is used to execute non-cutting operations on CNC machines, encompassing various machine commands. Therefore, it is sometimes referred to as miscellaneous code.

CAE-Aided Engineering

CAE software, which stands for Computer-Aided Engineering, is primarily used for analyzing the structural mechanical performance of complex engineering projects and products in engineering design, as well as optimizing structural performance. Examples include structural stress analysis, multibody dynamics, and computational fluid dynamics.

DNC-Distributed Numerical Control

DNC, Distributed Numerical Control, is a system that connects multiple CNC machines to a centralized computer system for remote control and data transfer for multiple machines working together.

MDC-Manufacturing Data Collection

DMC, or Manufacturing Data Collection, refers to the real-time collection of various data from machines and operators during the manufacturing process in order to better understand the production process and improve productivity and product quality.

Types of CNC Machines

CNC Milling

A CNC milling machine mainly consists of the bed, worktable, spindle, feed system, controller, and operation panel. Milling is a machining process where the cutting tool rotates while the milling machine itself does not. The rotating tool removes material to complete part processing, typically focusing on machining flat surfaces and block-like three-dimensional features. There are many types of milling machines, including vertical milling machines, horizontal milling machines, column-type, turret-type, C-frame, bed-type, and gantry-type milling machines.

CNC Turning

A CNC lathe mainly consists of the bed, headstock, tailstock, tool post, feed system, cooling system, controller, and operation panel. In lathe machining, the workpiece rotates while the cutting tool does not. It is primarily used for machining shaft-like parts, which are parts with cylindrical or conical shapes.

EDM Machining

There are various types of EDM, including wire EDM, Sinker EDM and small hole EDM. In EDM processes, the tool and workpiece do not physically touch (both are conductive materials). Typically, the tool serves as the cathode, connected to the negative pole of a DC pulse power supply, while the workpiece acts as the anode, connected to the positive pole of the pulse power supply. An insulating dielectric fluid fills the gap between the tool and workpiece during the process.

Other CNC Machines

• CNC Routers
• CNC Gear Hobbing
• Laser cutters
• Plasma cutters

Advantages of CNC Machining

Accuracy and High Precision: CNC machining can realize the accuracy that cannot be achieved by traditional manual machining, and the automated process does not require human intervention, which can reduce the errors in the machining process.

Fast and efficient: With CNC machining, parts can be machined within a few days, depending on the complexity of the project.

Cost Effective: The high degree of automation of CNC machining greatly reduces labor costs, and as long as the program settings remain unchanged, the same type of product can be machined an unlimited number of times

Wide Choice of Materials: CNC machining is suitable for a wide range of metals, plastics and composites. Common metals and plastics include: aluminum, stainless steel, copper, titanium, nylon, Teflon and PEEK.

Consistency: CNC machining uses computer programming for operations, ensuring that all manufactured parts have the same appearance and function, eliminating the possibility of human error.

Rapid Prototyping: CNC machining is ideal for producing small batches of parts, allowing you to obtain machined parts in a short time. CNC has relatively low startup costs, can achieve tight tolerances, high-quality surfaces, and complex geometries, resulting in high-quality prototype parts.

What are the Different Types of CNC Machining Processes?

CNC Milling

CNC milling is the most common manufacturing method in CNC machining and rapid prototyping. It primarily uses rotating cutting tools that move along axes to remove material from the workpiece. Simple parts are usually machined using 3-axis machines, while complex precision parts are generally suited for 5-axis machining.

CNC Turning

CNC turning excels in producing cylindrical or axially symmetric parts with high precision and efficiency. It can efficiently machine rotational features such as threads, grooves, and tapers.

CNC Drilling

CNC drilling uses a rotating cutting tool to move and drill holes in a fixed workpiece. Drilling is mainly used for holes with lower quality requirements, such as bolt holes, thread bases, and oil holes. For holes requiring higher precision and surface quality, subsequent processes such as reaming, boring, or grinding are used.

CNC Grinding

Grinding is a common machining method for CNC surface grinders. During the process, the grinding wheel contacts the workpiece surface, removing material through abrasion to achieve the desired finish. Grinding offers low cutting forces, high precision, and good surface quality, making it suitable for surface machining of various materials.

CNC Routing

CNC routing is used for cutting a variety of materials, such as soft metals, plastics, aluminum, and composites. In CNC routing, the workpiece remains stationary while the cutting tool moves in the X, Y, and Z dimensions, similar to CNC milling.

Others Machining Operations

• Broaching
• Lapping
• Sawing
• Honing
• Laser Cutting
• Plasma Cutting
• Water Jet Cutting

CNC Machining Materials

Metals

Metal is one of the most common materials used in CNC machining. The characteristics of different metals determine the ease or difficulty of machining them. CNC machining is the best and fastest way to process metal parts.

Here are some commonly used metals in CNC machining:

Aluminum: is the most abundant metal element in the Earth's crust and the most widely used metal in CNC machining. Its high strength-to-weight ratio and excellent corrosion resistance make it an excellent choice for lightweight parts requiring strength, such as aircraft engine components. Commonly used alloys include 6061 and 7075.

Copper: has excellent electrical and thermal conductivity, making it an ideal material for electronic components, and is more costly compared to aluminum or steel.

Titanium: is a high-performance metal and one of the hardest materials. Through CNC machining, titanium plays a crucial role in strategic fields such as aerospace and medical industries.

Stainless Steel: is a corrosion-resistant, high-strength, and machinable material suitable for CNC machining, capable of meeting various complex part machining needs.

Mild Steel: refers to carbon steel with a carbon content between 0.05% and 0.25%. It has lower strength but high ductility, easy weldability, and can achieve high-precision CNC machining.

Tool Steel: has excellent machinability and can be machined into various shapes and sizes of parts. It is used to manufacture high-precision tools, molds, and gauges.

Brass: is a copper-zinc alloy with good corrosion resistance, higher strength and hardness than pure copper, making the parts made from it highly durable.

Plastic

CNC machining can be used to mold plastic parts. The following plastics are commonly used in CNC machining.

ABS: is a thermoplastic commonly used in 3D printing and injection molding applications. However, CNC machining ABS is preferred for prototyping.

Nylon: is a high-performance engineering plastic with high strength, good toughness, and is not easy to break. CNC machining nylon can sometimes replace some metal materials.

PTFE: commonly known as Teflon, is a high-performance fluoroplastic with excellent chemical resistance and high temperature resistance.

Delrin: is a semi-crystalline, high-performance engineering plastic with high strength, stiffness, and wear resistance. It is widely used in automotive, mechanical, and electronic industries.

PEEK: is known as a "super engineering plastic" with excellent comprehensive properties. It has complex manufacturing processes and higher costs, making it a high-value-added material.

Acrylic: is the most excellent material among transparent plastics. It has good light transmittance, weather resistance and processing performance. It can replace glass in many fields. Acrylic has good machinability and can produce a large number of parts in a short time.

Other Materials

• Wood
• Miscellaneous

Material Considerations

CNC machining is compatible with a wide range of materials. However, before selecting a CNC material, consider the following factors:

• Hardness
• Mechanical properties
• Machinability
• Part function
• Dimensional tolerances
• Working Temperature
• Costs
• Application

Applications of CNC Machining

CNC machining is widely used in various industries, and CNC machining products can be seen everywhere in daily life.

Automotive: The precision of auto parts directly affects the performance and safety of the car. In automobile manufacturing, CNC machining of precision parts can produce more accurate and durable auto parts, such as engine parts, suspension system parts, etc.

Medical: Tight tolerances provided by CNC machining are crucial for producing high-performance medical components. It enables rapid prototyping for product testing and validation, meeting the precision, biocompatibility, and safety requirements of medical devices.

Aerospace: Due to the high precision and strength requirements of aerospace components, CNC machining can produce parts that meet strict standards, which is vital for aircraft safety. Common aerospace parts include aircraft engine blades, turbine components, and engine nozzles.

Electronics: Electronic devices require high precision and stability of components. CNC machining can achieve high precision, complex shapes, and surface treatments, meeting the requirements for precision, appearance, and functionality in electronic products, thus enhancing their performance and quality.

Robotics: CNC machining can precisely manufacture parts that meet specifications, which is particularly important in robotics because dimensional accuracy is key to building high-performance robots. Additionally, CNC machining allows for rapid prototyping, enabling quick and frequent modifications and manufacturing of complex robotic parts, accelerating the introduction of innovative robots.

Alternative Manufacturing Processes To CNC Machining

3D Printing

3D printing, also known as additive manufacturing, is a technology based on digital model files that constructs objects by printing layer by layer using materials like powdered metal or plastic that can be bonded together. It is widely used in engineering industries, especially for prototype design and the creation of lightweight geometric shapes.

Injection Molding

Injection molding is a commonly used plastic manufacturing process. It involves injecting molten plastic material into a mold of a specific shape, which then cools and solidifies to form the desired product. This process operates similarly to other manufacturing processes like blow molding, overmolding, and insert molding. It is favored for its efficiency, cost-effectiveness, and ability to produce complex-shaped products.

Die Casting

Die casting is similar to injection molding, where molten metal is injected into a mold at high pressure and high speed, and solidifies under high pressure to form the casting. The die casting process is often used for forming aluminum alloys, copper alloys, magnesium alloys, and zinc alloys. It can produce metal parts with complex shapes, clear contours, and thin walls with deep cavities.

What are the Trends in the CNC Machining Industry?

In the 2000s, the integration of new technologies such as internet technology, artificial intelligence, and sensor technology propelled the further development of CNC machining. Today, CNC machining has become an indispensable part of modern manufacturing, widely used in aerospace, automotive manufacturing, electronics industry, medical devices, and other fields, providing us with more advanced and convenient life experiences.

Whether you need rapid prototyping, small-scale production, or large-scale production, CNC machining is your first choice. In the future, artificial intelligence will be widely applied to CNC machining, with more axes being developed to create more complex geometries. Additionally, CNC machining will extensively use robots for unmanned production, driving the process of full automation. Finally, CNC machining will place greater emphasis on environmental protection and sustainability by adopting more eco-friendly materials and processes, reducing environmental impact, and lowering energy consumption.

Conclusion

Through this blog's discussion on the concept, process, history, advantages, machining techniques, and applications of CNC machining, we believe you now have a comprehensive understanding of CNC machining. If you still have various questions about your CNC machining project, you can contact our professional engineering team to get the answers you need.

DEK has been deeply involved in CNC machining services for many years, committed to providing you with efficient, high-quality precision parts machining services.

Additionally, we have compiled some common questions in CNC machining that we hope will be helpful to you. Please continue reading with us.

CNC Machining FAQs

What Are The Main Challenges in CNC Machining?

For the machining of complex parts, programming is difficult and requires particularly high programming skills from both the software used and the programmer.

What Are The Terminologies in CNC Machining?

Common terminologies in CNC machining include:

CAD: Computer-Aided Software

CAM: Computer-Aided Manufacturing

CAE: Computer-Aided Engineering

DNC: Distributed Numerical Control

G-code: Geometric Codes

M-code: Miscellaneous Machine Codes

What Are The Most Common Cutting Tools for CNC Machining?

Common cutting tools used in CNC machines include milling cutters, drills, turning tools, broaches, threading tools, taps, reamers, hobs, and hole-making tools.

How Much Does CNC Machining Cost?

Materials: The price differences between various materials can be significant. In the market, titanium alloys are much more expensive than aluminum alloys. Additionally, due to increased tool wear and slower cutting speeds, the cost of machining titanium will be higher than that of aluminum alloys.

Complexity: The more complex the geometry of the parts to be machined, the higher the machining costs. For example, impeller parts that require 5-axis machining are more expensive than regular square parts that can be machined with 3-axis.

Tolerance: The stricter the dimensional tolerance requirements, the higher the cost.

Surface Finish: Parts with strict surface finish requirements need special treatment, which increases machining time and cost.

Quantity: Mass production is cheaper than small batch production because bulk purchasing reduces the cost of raw materials, and the programming setup cost is distributed over more parts. The larger the quantity, the lower the cost per part.