Milling plays an important role in modern manufacturing, the foundation for creating precise, efficient products at reasonable costs. With the continuous development of technology, CNC milling promises to continue to make great contributions to the manufacturing and processing industry.

Traditional milling and CNC milling are effective mechanical processing methods, widely applied in many industries.
 

What is milling?

Milling is a mechanical processing method that uses a rotating milling cutter to cut the workpiece material (usually metal, plastic, wood, ...) to create products according to the desired shape and size.
 

What is CNC milling?

CNC milling is a mechanical processing method that uses computer-controlled machines (CNC) to create products from workpiece materials through the cutting motion of the tool and the relative motion between the tool and the workpiece.
 

Comparison of traditional milling and cnc milling methods

+ Similarities:

• Both are mechanical processing methods using rotating milling cutters to cut the workpiece material.
• Both can create products with complex shapes.

+ Differences:
 

CNC milling products have high precision

Advantages of CNC milling method

Thanks to the precise control of CNC machines, CNC milling offers many outstanding advantages over traditional machining methods, bringing many practical uses in many fields.

1. High precision:

• Accuracy reaches 0.01mm, thanks to precise computer control, meeting the strict requirements of many industries such as aerospace, medical, machine manufacturing, etc.
• Low error rate, minimizing material waste and production costs.
• The product surface is smooth, shiny, with few edges, ensuring aesthetics and high finishing.

2. Outstanding efficiency and productivity:

• CNC machines can operate automatically 24/7 with high precision, minimizing human intervention, improving processing efficiency.
• The milling cutter rotates at high speed, combined with the precise movement of the CNC machine to shorten processing time, increasing productivity.
• Suitable for large-scale production, meeting high market demand.

3. Flexibility and diverse processing capabilities:

• Processing many types of materials such as metal, plastic, wood, stone, etc.
• CNC machines can control the milling cutter to move in many different directions, creating products with complex shapes that are difficult to perform with traditional processing methods.
• Machining parameters such as cutter rotation speed, travel speed, cutting depth, etc. can be adjusted easily and quickly to suit each type of material and specific product requirements.

4. Saving production costs:

• High precision and low errors help minimize material waste during the processing process.
• High automation helps reduce labor needs, saving labor costs.
• The milling cutter is used more efficiently, reducing tool replacement costs.
• Helps shorten production time, minimize warehouse and transportation costs.

5. Expanding creativity and design capabilities:

• Thanks to its precise and flexible machining capabilities, CNC milling helps realize complex product design ideas that traditional machining methods cannot.
• The ability to process a variety of materials and shapes helps create unique, creative products that meet increasingly high market demands.
• Enterprises can create products with high quality, competitive prices and better meet market demands, thereby improving their competitiveness in the market.

6. Widely used:

Widely used in many industries today such as mechanics, electronics, medicine, aviation, household appliances, automobiles, etc.

CNC milling has many outstanding advantages

Disadvantages of CNC milling method:

In addition to the outstanding advantages, CNC milling also has some disadvantages that need to be considered before choosing this method:

1. High investment requirements:

• CNC milling machines and tools are more expensive than traditional machining methods.
• Installation and maintenance of CNC machines are more complicated, requiring high technical expertise and higher costs.
• It is necessary to invest in specialized CNC machining programming software.

2. High technical requirements:

• High technical level is required to operate CNC machines, program machining and maintain machines.
• Understand the properties of each type of material to choose the appropriate cutting mode.
• The ability to accurately program milling cutter paths to create products as required.

3. High noise:

• CNC machines operate with loud noise, affecting the working environment, requiring soundproofing measures or using earplugs to protect hearing.
• Affecting the surrounding area, requiring noise reduction measures such as installing a dust extraction system, reducing processing speed, etc.

4. Limiting the machining of thin parts:

Due to the cutting force of the milling cutter, thin parts are easily deformed during the machining process.
 

Standard process in CNC milling

In the simplest terms, CNC milling involves a four-step process:

Step 1: Create a CAD model

The machinist uses a design program such as Autodesk Fusion 360 to create a CAD model of a specific part.

Step 2: Convert the CAD model to the CNC machine

Next, import the CAD model into the CAM computer-aided manufacturing system. Done correctly, you will have a series of digital instructions that tell the CNC machine what to do—known as G-code. G-code commands allow the machine to determine where to move and how fast to do it to create a specific part.

Step 3: Set Up the CNC Mill

Mount the workpiece or block of material to the machine bed and make sure it is properly aligned using measuring tools or touch probes. Install the machine spindle and go through all the steps necessary to set up the mill.

Step 4: Start the Machining Process

Load the program to start the CNC milling process. Specialized cutting tools rotate at high speeds or a fixed rotation per minute to remove material from the workpiece until it accurately replicates the desired part.
 

Standard CNC Milling process delivers superior quality

CNC Milling design considerations

CNC milling is a highly precise process. However, it is not possible to produce a part with absolute perfection. While CNC milling can produce parts with over 99% accuracy, certain applications require tolerances below 1%, which is why tolerances are required.

Tolerances are the permissible variations from the specified dimensions and shape of a machined part that still allow the part to function as intended. Designers specify tolerances during the design phase. However, the maximum tolerances that can be achieved depend on the manufacturing process.

For CNC milling operations and machines, standard tolerances are

• Milling (3-axis): ± 0.005″ or 0.13 mm
• Milling (5-axis): ± 0.005″ or 0.13 mm
• Engraving: ± 0.005″ or 0.13 mm
• Rail cutting tolerance: ± 0.030″ or 0.762 mm
• Screw machining: 0.005″ or 0.13 mm

- CNC milling geometry and features

When designing parts for CNC milling, it is important to take into account the limitations of the machine. Here are some features and geometry considerations for CNC milling.
 

• Avoid curved holes: These features cannot be created because CNC milling tools are rigid and cannot bend through a part.
• Avoid Hidden Cuts: Similar to curved holes, hidden cuts are inaccessible features.
• Avoid Too Thin and Tall Walls: CNC milling exposes parts to high vibration. Thin and tall walls are prone to breakage during machining.
• Design Radius Internal Edges: Cutting tools are typically round, making it impossible to create straight internal corners.
• The size limit for CNC milled parts is determined by the milling machine. We recommend a maximum size of 1.2 mm x 1 mm x 1 mm.

What is the difference between CNC Milling and CNC Turning?

While CNC milling and CNC turning rely on CNC systems, there are still key differences between the two machining processes.

• CNC turning is performed to create conical or cylindrical surfaces. The turning process requires a lathe, a machine tool that can rotate a workpiece around a rotating axis to perform various operations such as cutting, drilling, turning, and threading.
• CNC milling is used to create a flat surface using a milling machine. It requires a multi-point cutting tool or a mill-cutting machine. Unlike turning, milling relies on intermittent cutting and multiple machine steps.

Popular effective Milling machining methods today

Currently, there are many different milling machining methods used, each with its own advantages and disadvantages suitable for each specific case. Below are some popular effective milling machining methods today:
 

1 - Face Milling

Face milling is the machining of a flat surface perpendicular to the axis of the cutter. The milling cutter used in this process has teeth on both the periphery and the tool face, each playing a separate role.

Advantages:

• Produces a smooth, flat surface with high precision
• Can be applied to a variety of machining methods, including vertical milling and horizontal milling.
• Quick and accurate machining, saving time and effort.
• Suitable for a variety of materials and part shapes.
• Simple, easy-to-control machining process.

Applications:

• Machinery industry: Machining flat surfaces for machine parts, molds, tools such as: flanges, base faces, guide faces, coupling faces, etc.
• Automotive industry: Machining flat surfaces for engine parts, chassis, transmission systems such as: cylinder head planes, gearbox housing planes, wheel shaft planes, engine housing faces, body surfaces, etc.
• Aerospace Industry: Surface machining for aircraft engine parts, fuselage, aircraft wings such as: propeller plane, aircraft wing plane, aircraft fuselage plane, etc.

Face milling - The perfect solution for smooth flat surfaces

2 - Plain milling

This is a machining method that uses a milling cutter with a rotating axis parallel to the surface to be milled. This method is performed with the workpiece fixed parallel to the milling machine table, while the cutter is mounted on the machine's main shaft. The tool holder is supported in a horizontal plane between the main shaft and the tool holder. The workpiece is clamped tightly to the milling table.

Advantages:

• Plain milling can remove material quickly and efficiently.
• Can produce smooth flat surfaces with high precision.
• Can be applied to a variety of materials and part shapes.
• The plain milling process is relatively simple and easy to operate.

Application: Used in many other industries such as: Agricultural machinery manufacturing industry, construction, electronics, shipbuilding,...
 

3 - Corner milling

Corner milling is a mechanical processing method that uses a milling cutter with a rotating axis perpendicular to the surface of the workpiece to be machined. This method is applied to create flat, angular surfaces with high precision, meeting the strict requirements of many industries.

To meet diverse machining needs, corner milling uses two types of specialized milling cutters:

• Single corner milling cutter: This type of cutter has cutting teeth on the corner and large flat surface, suitable for machining common angles such as 45° or 60°.
• Double corner milling cutter: The double corner milling cutter is designed with V-shaped cutting teeth and a conical surface, providing optimal efficiency when machining flat surfaces at 45°, 60° and 90° angles.

Advantages:

• Corner milling creates angular surfaces with high precision
• The machining process is fast, saving time and effort.
• Can be applied to many different types of materials and detailed shapes.
• The angular surface after machining is smooth, shiny, and increases the aesthetics of the detail.

Applications:

• Machining machine parts with edges such as shafts, gears, joints, etc.
• Machining molds, tools.
• Machining decorative and fine art details.

4 - Mold milling:

Mold milling is an optimal mechanical processing method to create uneven contours on the workpiece, opening up diverse machining capabilities for many types of details.

Advantages:

• Shaping can be completed in a single cut, saving time and effort compared to other machining methods.
• The surface after machining by mold milling is smooth, shiny, and increases the aesthetics of the detail.
• Although the processing speed is slower than conventional milling, mold milling still ensures high efficiency in creating complex contours.

Applications:

• Mold milling is commonly used to mill cavities and beads with semi-circular or quarter-round radius shapes on workpieces.
• It is capable of creating complex patterns or milling multiple complex surfaces in one cut, meeting diverse machining needs.
• It can be used to shape semi-circular and semi-circular contours, providing high precision and aesthetics for the part.

Types of CNC milling machines

CNC milling machines can be classified according to the main axis direction as vertical milling machines and horizontal milling machines. Before choosing between these two types of milling machines for a milling project, the operator must consider the needs of the project such as the shape and size of the part and the number of surfaces to be milled.

Another major classification of CNC milling machines is by the number of axes and axis configuration. In CNC milling, the axis refers to the direction of movement of the workpiece or cutting tool. Multi-axis milling operations include 3-axis, 4-axis, and 5-axis milling. These operations allow for the rapid and accurate production of parts from your design, ranging from simple shapes to complex geometries. 3-axis and 5-axis CNC milling machines are the most common types of CNC milling machines.
 

- 3-axis CNC milling machine

The cutting tool or workpiece in a 3-axis CNC milling machine has three degrees of freedom. This means that it can move in three linear directions; the X-axis (left and right), the Y-axis (back and forth), and the Z-axis (up and down). In order for the cutting tool to reach certain areas of the workpiece, the workpiece must be manually repositioned.

Benefits of 3-axis CNC milling:

• The process is easy to program and can produce parts with simple shapes, with high accuracy
• It has a high production capacity
• The machining cost per part is relatively low
• 3-axis CNC milling machines are cheaper than 5-axis CNC milling machines

Limitations of 3-axis CNC milling:

• For some processes that require more access to the cutting tool, the need to constantly change the position of the workpiece reduces accuracy
• The tool cannot reach certain areas of the workpiece
• Complex geometries and designs are more difficult to achieve with a 3-axis CNC milling machine than with a 5-axis CNC milling machine

- 5-axis CNC milling machine

In addition to the three linear axes that can be achieved in a 3-axis milling machine, a 5-axis CNC milling machine has two rotary axes. In most milling machine configurations, the cutting tool can only move along three linear axes. The workpiece performs the remaining two rotations, thus allowing the cutting tool to access another area.

5-axis CNC milling machines can be classified into indexing milling machines and continuous milling machines. In a 5-axis indexing milling machine, the cutting tool has to stop moving temporarily while the workpiece rotates. However, in a 5-axis continuous milling machine, the cutting tool does not need to stop. The workpiece rotates simultaneously as the cutting tool moves.

Benefits of 5-axis CNC milling:

• It eliminates the need to manually reposition the workpiece
• It produces parts with very complex shapes and designs with very high precision
• The surface finish of a 5-axis CNC milled part is very smooth. Virtually no machining traces

Limitations of 5-axis CNC milling:

• Machining costs per part are 60% and 100% higher in indexed 5-axis CNC milling and continuous 5-axis CNC milling, respectively, than in 3-axis milling.
• 5-axis CNC milling machines are bulkier and more expensive than 3-axis CNC milling machines

Commonly used materials in milling

The materials used in milling play an important role, affecting the efficiency, accuracy and quality of the product. Below are some common materials used in milling:
 

1. Metal

Metal is the most common material that undergoes the machining process. Milling can create parts from any type of metal.

- Advantages:

• Metal has high hardness and durability, helping them withstand large loads and stresses during the machining process. Thanks to that, the parts machined from metal have a long life and stable operation.
• It can be easily machined by many different methods, including milling, turning, planing, grinding, etc. This helps to create parts with high precision and meet complex design requirements.
• Metal is a recyclable material, helping to protect the environment and save resources.
• There are many types with different prices, suitable for many needs and budgets.

- Popular types of metals in milling:

+ Steel:

• Steel is the most commonly used metal in milling due to its hardness, durability and good machinability.
• There are many different types of steel such as carbon steel, alloy steel, stainless steel, each with properties suitable for specific applications.

+ Cast iron:

• Cast iron has lower hardness than steel but is easier to process and has a cheaper price.
• Cast iron is often used to process machine parts with light loads and low rotation speeds.

+ Aluminum:

• Aluminum is a light material, easy to process and has good thermal conductivity.
• Aluminum is often used to process machine parts with light loads and high rotation speeds.

+ Brass:

• Brass has high ductility, is easy to process and has good corrosion resistance. Brass is often used to process decorative details and high-precision details.
• Metals are commonly used in milling processes

2. Plastic Materials

Plastic materials are increasingly widely used in milling, providing many advantages and opening up new processing possibilities.

- Advantages:

• Plastic is lighter than metal, helping to reduce the weight of the machined part, especially important for applications in the aviation, automotive and robotics industries.
• Highly flexible, helping the machined part to have good impact resistance and crack resistance.
• Good corrosion resistance, suitable for harsh environments such as chemicals, seawater.
• A good insulating material, safe to use in electrical applications.
• Can be easily machined by milling method, helping to create high-precision parts and meet complex design requirements.

- Common types of plastics in milling:

+ Thermoplastics:

• Thermoplastics can be easily melted and shaped, suitable for applications that require machining many parts with complex shapes.
• Some common types of thermoplastics in milling include: ABS, PC, POM, PE, PP.

+ Thermosetting plastics:

• Thermosetting plastics have high hardness, good heat resistance and good chemical resistance.
• Some common types of thermosetting plastics in milling include: epoxy, phenolic, polyurethane.

3. Other materials

Milling is not only limited to metals and plastics but also extends to many new materials with breakthrough advantages and machining capabilities.

- Composite materials:

• Combining the advantages of many materials, creating hardness, durability, light weight and high resistance.
• Material types include: FRP, Carbon, Metal matrix composites, Polymer matrix composites, Ceramic matrix composites.
• Applications in aerospace, automotive, industrial, medical, sports industries.

- Ceramic materials:

• High hardness, good heat resistance, corrosion resistance, good insulation.
• Material types include: Technical ceramics, Zirconia ceramics, Silicon nitride ceramics.
• With advantages: High heat and chemical resistance, high hardness, high precision.
• Applications in medical, semiconductor, electronic, aerospace industries.

How much does it cost to mill?

The cost of CNC milling is an important factor to consider when choosing a manufacturing method for your product.

- Factors affecting the cost of milling:

• Size and complexity of the part: The larger and more complex the part, the higher the machining cost.
• Workpiece material: The harder the workpiece material, the more difficult it is to machine, the higher the machining cost.
• Milling method: Some milling methods require high technology and modern equipment, leading to higher machining costs.
• Precision and tolerance: The part requires high precision and tolerance, the higher the machining cost.
• Number of parts to be machined: The more parts, the cheaper the machining cost per part.

- Reference price for milling:

The price for milling can range from a few hundred thousand VND to a few million VND for each part, depending on the factors affecting the cost as mentioned above.

- For example:

• Milling a simple small plastic part can cost a few hundred thousand VND.
• Milling a complex large metal part can cost a few million VND.

Intech Company specializes in precision and reputable CNC milling

Intech Company is proud to be the leading provider of CNC milling services in Vietnam, with many years of experience and a team of skilled technicians. We are committed to bringing customers high-quality milling products, meeting the most stringent requirements for accuracy, finish and aesthetics.

With a modern, advanced CNC milling system imported from prestigious brands around the world, Intech can meet all customers' milling needs, from simple to complex.

- Intech commits:

• The quality of milling products is highly accurate, meeting all customer requirements.
• Competitive prices, suitable for all budgets.
• Fast processing progress, ensuring on-time delivery as required.
• Professional, dedicated customer service.

Intech is always ready to provide free advice to customers on CNC milling solutions that best suit your needs. Contact Intech today for advice and detailed quotes on CNC milling services!

- Contact information:

• Hotline: 0966 966 205
• Email: info@intech-group.vn
• Website: https://intechvietnam.com/