CNC milling is one of the CNC machining processes that provides a precise and efficient method to produce complex parts and components. As industries evolve, the role of CNC milling becomes increasingly important. This article will describe how CNC milling service are used for rapid prototyping and production, as well as the advantages, disadvantages, types, and more of CNC milling.
What is CNC Milling?
The Basics Of CNC Mills
CNC milling is a precise subtractive manufacturing process that utilizes rotating cutting tools to remove material from a workpiece. This method is particularly effective for profile cutting harder materials, making it ideal for industries requiring durable components. CNC mills excel in producing complex shapes and features with high accuracy. The process is generally performed on milling machines or boring machines, capable of handling tasks like cutting planes, grooves, and forming intricate surfaces such as splines, gears, and threads. Additionally, they are widely used in mold-making, where special-shaped surfaces are crucial.
The Object Of CNC Milling
The object of CNC milling involves creating parts with precise geometries and high-quality finishes. It focuses on two main categories: Plane Parts and Surface Parts.
Plane Parts are flat and have simple geometries, ideal for tasks like slotting and face milling.
Surface Parts have curved and irregular surfaces, and the shape of the parts is more complex, requiring milling processes of more than 3 axes.
CNC Milling Process
The CNC milling process consists of several key steps. The first step is to create a design of the part using CAD software, containing the exact specifications of the part. The next step is to convert the CAD file into a language that the machine can use, generating a series of G-codes.
The operator places the material cut to specific dimensions on the machine. Typically, the block of material is always called a blank or workpiece. The workpiece is then mounted on the machine or in a vise. Since the computer controls the CNC tool to move to preset coordinates, precise positioning and alignment of the workpiece is essential to manufacturing high-precision parts. For example, specialized metrology tools, probes, are ideal solutions for this step.
Finally, the workpiece is ready for machining. The machine uses specialized cutting tools that rotate at high speeds to remove material from the workpiece, following a programmed path to achieve the desired shape.
Types of Milling Cutters
Milling cutters come in various forms to handle different types of operations. They are used for axial milling, where the cutter works along the axis of the workpiece, lateral milling, where the tool moves perpendicular to the axis, or bi-directional milling, which involves both directions. Some common types include end mills for precise vertical cutting, face mills for larger surface areas, and ball nose cutters, which are ideal for creating curved surfaces.
Types of CNC Mills
CNC mills are categorized based on the number of axes they operate, influencing their capability to create complex parts.The table below shows the advantages and disadvantages of different CNC milling machines.
Type | Explanation | Advantages | Disadvantages |
3-Axis CNC Mills | Moves along X, Y, Z axes. Used for simple tasks like drilling, milling. | Cost-effective. Good for shallow parts. | Limited with deep cavities. Surface finishing basic. |
4-Axis CNC Mills | Adds a rotational axis. Allows multi-sided machining without repositioning. | Multi-sided machining. No reposition needed. | N/A |
5-Axis CNC Mills | Moves along X, Y, Z, and two rotational axes. Ideal for complex shapes. | High precision. Handles deep, hard material. | Longer setup and programming time. |
Advantages of CNC Milling
- Rapid Turnaround:CNC milling allows for fast production cycles, ensuring quick lead times.
- High Precision Tolerances:The process achieves high accuracy, making it suitable for parts that require tight tolerances.
- Scalability:CNC milling is flexible, supporting small-batch prototyping and large-scale production efficiently.
- Material Selection:It can handle a wide range of materials, from common choices like aluminum and plastic to specialized materials such as titanium.
- Suitable for rapid prototyping：CNC milling is particularly advantageous for rapid prototyping because it allows for producing highly detailed and functional prototypes.
Custom CNC Milling Materials
Here’s a breakdown of some popular materials used in CNC milling:
Aluminum
Aluminum is renowned for its lightweight, corrosion resistance, and excellent machinability, making it a favored choice in the aerospace and automotive industries. Popular grades include 6061 aluminum, known for its versatility and strength, and 7075-T6 aluminum, which offers high strength-to-weight ratio, making it ideal for structural components.
Stainless Steel
Stainless steel is prized for its corrosion resistance and strength. It is often used in medical equipment, kitchenware, and construction. Its durability makes it suitable for high-stress applications.
Mild Steel
Mild steel, characterized by its low carbon content, is easy to machine and weld. It is commonly used in construction and manufacturing due to its affordability and availability.
Brass
Brass materials such as Brass C27400 and Brass C36000 boast excellent electrical conductivity and corrosion resistance. These properties make brass ideal for plumbing, electrical components, and decorative applications.
Copper
Copper materials such as Copper C101 (T2) and Copper C110 (TU0) are known for their superior thermal and electrical conductivity. They are commonly used in electrical components and heat exchangers.
Alloy Steel and Tool Steel
These steels are used for their strength and toughness, often applied in high-stress environments. Tool steels are especially significant in tool and die making due to their hardness and resistance to abrasion.
Titanium
Titanium is lightweight yet strong, with excellent corrosion resistance. It is used in aerospace, medical implants, and high-performance automotive parts due to its ability to withstand extreme conditions.
Inconel and Invar
These nickel-based alloys are known for their durability at high temperatures. Inconel is often used in aerospace and chemical processing, while Invar is utilized where minimal expansion is required.
POM (Polyoxymethylene)
Known for its high stiffness and low friction, POM is an excellent choice for parts requiring precision and wear resistance, such as gears and bearings.
Nylon
A strong, flexible plastic that offers good wear resistance and strength. It’s commonly used in industrial parts like bushings and pulleys due to its ability to withstand high mechanical stress.
ABS (Acrylonitrile Butadiene Styrene)
This plastic is lightweight and has excellent impact resistance. It’s often used for prototypes and parts that require toughness and durability, such as automotive components and housings.
PEEK (Polyether Ether Ketone)
Known for its high-temperature resistance and strength, PEEK is ideal for applications in extreme environments, such as aerospace and medical devices. It’s one of the strongest plastics available.
PVC (Polyvinyl Chloride)
PVC is valued for its chemical resistance and affordability. It’s used in parts exposed to harsh environments, such as pipes and fittings in chemical processing.
CNC Milling Tolerances
CNC milling can achieve very high tolerances, but the actual achievable tolerances also depend on factors such as material type, part complexity, and the capabilities of the milling machine.
- Standard Tolerances: Typically, CNC milling can achieve tolerances of ±0.005 in (±0.13 mm) for most metals and ±0.010 in (±0.25 mm) for plastics.
- Tight Tolerances:For more demanding applications, such as in aerospace or medical industries, CNC milling can achieve tolerances as tight as ±0.001 in (±0.025 mm).
Factors Affecting Tolerances
- Material: Softer materials like plastics may be more challenging to hold tight tolerances due to their flexibility and thermal properties. In contrast, metals like aluminum and steel generally offer better dimensional stability.
- Part Geometry: Complex shapes with intricate features may require advanced CNC programming to maintain tolerances across all dimensions.
- Machine Calibration: The accuracy of the CNC machine itself, including regular maintenance and calibration, plays a significant role in achieving precise tolerances.
Standard Surface Finishes for CNC Milling
Here is the table for standard surface finishes for CNC milling:
Surface Finishes | Service | Applicable to | Machining Marks | Tolerances |
Anodized | Protective and decorative oxide layer | Aluminum, titanium | Removed | Moderately affected |
Bead Blast | Textured, matte finish | All metals | Lightly reduced | Slightly affected |
Powder Coat | Protective color layer | All metals | Fully covered | Moderately affected |
Pickling | Chemical cleaning and descaling | Stainless steel, aluminum | Removed | Not affected |
Brushed | Directional, smooth finish | All metals | Partially visible | Not affected |
Polishing | Smooth, reflective finish | All metals | Removed | Not affected |
Black Oxidize | Corrosion protection with a black finish | Steel | Partially visible | Not affected |
Tumbling | Smoothing surface irregularities | All metals | Reduced | Not affected |
Electropolish | Smooth, bright surface | Stainless steel, aluminum | Removed | Not affected |
Heat Treatment | Altering material properties through heat | Steel, stainless steel | No effect | Can be affected |
Electroplating | Protective and decorative metal coating | All metals | Covered | Can be affected |
This table includes the most common surface finishes used in CNC milling, along with their effects on the material’s surface, cosmetic quality, and tolerances.
Applications of Custom Milled Parts
Custom milled parts are used in various industries due to their precision and versatility:
- Automotive:Engine components, brake calipers, and custom suspension parts are commonly produced using CNC milling for high performance and durability.
- Industrial Machinery: CNC milling is used to manufacture industrial machinery parts such as gearboxes, machine tool components, and custom jigs and fixtures.
- Medical and Dental:CNC milling is used to manufacture parts used in the medical and healthcare fields, such as surgical instruments, orthopedic implants, and crowns.
- Aerospace:Aircraft brackets, engine casings, and control panels rely on custom milled parts for high precision and strength.
- Consumer electronics:CNC milling is used to produce smartphone casings, camera components, and laptop bodies.
- Robotics: Robotic arms, gears, and end effectors require custom milled parts for mechanical precision and reliability.
- Military: 3-axis and 5-axis machines are used to produce custom milled parts for military aircraft, vehicles, weapons, and submarines.
- Oil and Gas: Valve assemblies, pump parts, and pipe connectors are milled for robust performance in harsh environments.
CNC Milling Design Guidelines
Recommended size | |
Radii | The inside radius should be at least 1/3 of the cavity depth. Use a larger radius whenever possible. |
Thread and Tapped Hole | Diameter φ1.5-5mm, Depth: 3 times the diameter. Diameter φ5mm or more, Depth: 4-6 times the diameter.(EASIAHOME can produce threads of any size according to customer requirements.) |
Minimum Wall Thickness | Metal: 0.8 mm; Plastic: 1.5 mm.The thicker the wall, the better the structural integrity. |
Text | CNC milling: minimum width 0.5mm, depth 01mm.Embossed or engraved text should have a font size of at least 20 points for clarity. |
Holes | Minimum diameter is 1 mm. For best results, the hole depth should not exceed 4 times the diameter. |
How to Choose a High-Quality CNC Milling Manufacturer?
Selecting a reliable CNC machining manufacturing partner is essential for ensuring precision and quality. Key factors to consider include:
- Quotation Timeliness: Ensure the CNC milling manufacturers provides fast and accurate quotes, allowing for efficient decision-making.
- Delivery Time: Confirm if the CNC milling service provider can meet your required timelines, especially for urgent projects.
- Order Flexibility: Check if there’s a minimum order quantity and whether the manufacturer can accommodate small or large batch orders.
- Competitive Pricing:Assess if the pricing offers good value without compromising on quality.
- Technical Support:Look for manufacturers with professional technical support to guide design improvements.
- Equipment Quality:Ensure the workshop has complete, up-to-date machining equipment.
- Precision: Verify the manufacturer’s capability to meet specific high quality CNC milled parts tolerances.
- Quality Control: Confirm if they conduct rigorous quality control tests on all parts.
If you are eager to learn more about CNC machining or need a customized CNC milling parts project, take action now and contact us. We will provide you with all-round support!
Frequently Asked Questions (FAQs)
Q: What Is The Difference Between Milling And Drilling?
A: Drilling: Drilling is only suitable for axial drilling, that is, the drill bit always penetrates the material in a direction perpendicular to the workpiece . Drilling is only used to create cylindrical holes and cannot be used for lateral material removal.
Q:What Is the Difference Between CNC Milling and CNC Lathe?
A: CNC milling uses rotating cutting tools to remove material by moving across the workpiece in multiple directions, allowing for complex shapes and features. CNC lathes, on the other hand, rotate the workpiece itself while a stationary tool removes material, making them ideal for creating symmetrical, cylindrical parts.
Q:What Is The Surface Finish Standard?
A: We offer the following surface finish standards: Typical surface roughness is Ra 3.2-1.6μm; Smooth surface roughness is Ra 1.6-0.8μm; Superfinished surface roughness is Ra 0.8-0.2μm.
Q: What Types of Cutting Tools for Milling?
A: End Mills: Used for profile milling, face milling, and plunging operations.Face Mills: Designed for high-efficiency surface cutting of large flat areas.Ball Nose Cutters: Ideal for 3D contouring and complex surface milling.Slot Drills: Primarily used for creating slots and pockets.Chamfer Mills: Create beveled edges for deburring or aesthetic purposes.
Q: What Materials can EASIAHOME Mill?
A: EASIAHOME provides milling processing for a variety of materials, including aluminum, stainless steel, copper, titanium alloy, plastic, etc. These materials are suitable for different industrial needs and meet precision processing requirements.
Q: What Are The Maximum And Minimum Dimensions for CNC Milling At EASIAHOME?
A: Large: 2000 x 1500 x 200 mm (78.7 x 59.0 x 7.8 in)
Small: Minimum part size is approximately 0.39 x 0.39 x 0.39 in (10 x 10 x 10 mm)
Q: What Is CNC Milling Tolerance Standard That EASIAHOME can Guarantee?
A: Our standard tolerances for CNC milled metals are IS0 2768-m and for plastics are IS02768-c. We are committed to precise measurements to provide our customers with consistent, high-quality results optimized for search visibility.
