Basic Guide To CNC Machining Of Aluminum
CNC Machining aluminum parts refers to the precise cutting, machining and processing of various shapes of aluminum alloy raw materials through various advanced machining methods and technologies to manufacture aluminum parts with high precision, high quality and high reliability.
Aluminum CNC machining usually includes material selection, material treatment, CNC machining aluminum, surface treatment and quality testing.
Materials Selection:
Pure aluminum refers to aluminum material without adding other elements. Its chemical symbol is Al. It has excellent characteristics such as light weight, good electrical conductivity and corrosion resistance. However, due to the lower strength of pure aluminum materials, aluminum alloys are usually used instead in industrial applications.
Aluminum alloy is the most commonly used CNC machining material, and It refers to composite materials made by adding other elements (such as copper, magnesium, zinc, manganese, etc.) to aluminum. It has excellent mechanical properties, including Strength To Weight Ratio, Good Thermal Conductivity, High Corrosion Resistance, Weldability, and other characteristics.
Strength To Weight Ratio:
Aluminum alloys are one of the materials with a high weight to strength ratio because they are relatively light but have sufficient strength and hardness. Compared with other metallic materials, aluminum alloys have a lower density and, therefore, a higher weight-to-strength ratio. For example, aluminum alloy 6061-T6 has a weight-to-strength ratio of approximately 1.0 kN·m/kg, while steel has a weight-to-strength ratio of approximately 0.2 kN·m/kg. This means that the 6061-T6 alloy can be used to make lighter parts than steel for the same strength requirements.
Thermal Conductivity:
Aluminum alloys have high thermal conductivity, which means they can quickly transfer heat to the surrounding environment. The following are the thermal conductivity of some common aluminum alloy materials:
Aluminum Types:
Thermal Conductivity
6061 Aluminum :
167 W/mK
7075 Aluminum :
130 W/mK
2024 Aluminum :
121 W/mK
5052 Aluminum :
138 W/mK
6063 Aluminum :
201 W/mK
It should be noted that the thermal conductivity of aluminum alloy is related to its chemical composition, state, temperature and other factors. Therefore, when selecting materials, appropriate aluminum alloy materials should be selected according to specific application scenarios, and heat dissipation design should be combined to optimize the thermal conductivity of components.
Corrosion Resistant:
Aluminum is a metal material with excellent corrosion resistance, mainly because its surface will form a natural oxide layer, which can effectively prevent further oxidation and corrosion of materials.
Machinability:
The machinability of aluminum material is very important for CNC machining. It is necessary to select materials that are easily machined to ensure efficient production and machining quality.
Weldability:
Aluminum has good weldability, but the specific weldability varies with the composition and state of the material. Generally speaking, aluminum alloy materials with high purity and low alloy content have better weldability. At the same time, heat treatment may also affect the weldability of materials.
Material Pretreatment:
In Aluminum CNC Machining Process, material pretreatment is a very important step; it can ensure that the machined parts have a certain precision, surface quality and performance. The following are several common pretreatment methods for aluminum materials:
Deburring and Oiling:
Before material processing, it is necessary to deburring and oiling the surface of aluminum material to ensure that the material’s surface is smooth and clean and will not interfere with subsequent processing and coating processes.
Heat Treatment:
Heat treatment is a method of changing the structure and properties of materials by heating and cooling them. For CNC aluminum machining, the common heat treatment methods include aging treatment and quenching treatment. Aging treatment can improve the strength and hardness of aluminum. Quenching treatment can improve the corrosion resistance of aluminum material.
Pre-Welding Treatment:
If the parts need to be welded, the welding area must be pretreated, such as removing the oxidation layer, removing dirt, etc. This ensures the quality of welded joints and improves reliability of welded joints.
Surface Treatment:
Aluminum alloy components usually require surface treatment to improve corrosion resistance, wear resistance and aesthetic properties. Common surface treatment methods include anodic oxidation, electroplating, spraying, etc.
Aluminum CNC Machining
CNC machining services can produce aluminum alloy parts of various complex shapes. The following are some basic knowledge of aluminum CNC machining:
CNC Machines Selection:
Common CNC machine types are vertical machining center, horizontal machining center, gantry machining center and so on. In processing aluminum parts, the available choice of a high-speed machining center is because it has the advantages of high speed, high precision, and high efficiency.
Tool selection:
Machining tool is the key to CNC aluminum machining. Selecting the right tool can improve machining efficiency and quality. Aluminum alloy machining tool commonly used with end milling cutter, ball end milling cutter, T – cutter, and so on.
Cutting Parameters:
Cutting parameters refer to the rotation speed, feed speed and cutting depth. Higher cutting and feed speeds for aluminum alloy materials are usually used to improve machining efficiency. However, it is necessary to avoid excessive cutting depth so as not to cause excessive cutting force and premature tool wear.
Clamping Mode:
Aluminum alloy material has good plasticity and toughness, so the clamping must avoid too tight a clamping force so as not to cause material deformation and damage. Common clamping methods include mechanical clamping, vacuum adsorption and so on.
Aluminum CNC machining needs to pay attention to safety and maintenance, timely replacement of severely worn tools and fixtures, and processing equipment maintenance and maintenance, to ensure the quality of processing and production efficiency.
Surface Finishes
Aluminum surface treatment is a series of processing technology to increase the surface’s hardness, corrosion resistance and beauty. Common surface treatment methods for aluminum parts include:
Anodic Oxidation：
After anodizing aluminum parts, the oxide film formed on the surface of aluminum parts has excellent corrosion resistance, wear resistance and insulation and has good decorative properties, which can be used in high-grade electronic products, auto parts, aerospace fields, etc.
After anodizing, there will be some holes and tiny cracks on the surface of the aluminum parts. These tiny defects will affect the sealing performance of aluminum parts. Therefore, for applications that need to maintain the tightness of aluminum parts, special sealing treatment is required on the oxide film to improve the tightness of aluminum parts.
Hardening Treatment:
By heating and cooling, a thin film is generated on the surface of the aluminum parts to improve the hardness and wear resistance of the surface of the aluminum parts. Hardening treatment applies to aluminum parts requiring wear resistance and compressive properties, such as automotive engines, aircraft engines and other components.
Paint Coating:
Aluminum parts coating can improve aluminum parts’ corrosion resistance and decorative and oxidation resistance. Still, it also can add a protective layer for aluminum parts and extend the service life of aluminum parts.
When spraying, choosing the appropriate spray gun, paint, solvent and coating conditions is necessary to ensure the coating quality and adhesion.
Electroplating:
Aluminum parts coating can improve aluminum parts’ corrosion resistance and decorative and oxidation resistance. Still, it also can add a protective layer for parts and extend the service life of aluminum parts.
When spraying, choosing the appropriate spray gun, paint, solvent and coating conditions is necessary to ensure the coating quality and adhesion.
Sand Blasting:
Aluminum sandblasting removes the oxidation layer, dirt and blemishes on the surface of parts by spraying sand particles at high speed to obtain a smooth and uniform surface and increase the decorative and corrosion resistance of aluminum parts.
The process of sandblasting aluminum parts is as follows:
- Check the surface of the parts for bumps and other defects.
- In the sandblasting room, place the parts in a fixed position and pay attention to the distance between them and other parts to avoid mutual interference.
- Adjust the nozzle of the sandblasting machine to the appropriate position and start spraying sand. The type and size of sand need to be selected according to the material and requirements of aluminum parts.
- After sandblasting, the aluminum parts are cleaned with compressed air to remove any remaining sand and dirt.
Quality Inspection
Aluminum surface treatment is a series of processing technology to increase the surface’s hardness, corrosion resistance and beauty. Common surface treatment methods for aluminum parts include:
Appearance inspection:
Check whether there are scratches, dents, bubbles, cracks, burrs and other defects on the surface of parts and whether the size and shape of aluminum parts meet the requirements.
Size Detection:
Use measuring instruments (such as a micrometer, vernier caliper, height gauge, etc.) to detect the size of parts, and compare it with the design drawings or standard requirements to determine whether the size is up to standard.
Material Testing:
A chemical analysis instrument is used to analyze the material of aluminum parts to determine whether it meets the requirements.
Mechanical Property Testing:
A universal testing machine and other equipment are used to test the strength, hardness, toughness and other mechanical properties of aluminum parts to determine whether it meets the requirements.
Packaging Inspection:
The packaging of the aluminum parts is inspected to ensure that the parts are not damaged or contaminated and that the packaging complies with shipping requirements.
FAQs
Q: What is CNC Machine?
A: CNC machine tool is a kind of automatic processing equipment to control machine tool through a computer numerical control (CNC) system. It can automatically carry out machining operations such as cutting, drilling, grinding and milling according to pre-input programs and instructions, with high precision, high efficiency and good repeatability.
Q: What are the applications of CNC machines?
A: CNC machine tools can be widely used to process various materials, including metal, plastic, wood, ceramics, etc., for manufacturing various parts, workpieces, molds, etc.
Q: Aluminum Vs Steel, What’s the difference?
A: Aluminum is lighter than steel but has low strength and good corrosion resistance. It is suitable for applications with high lightweight and corrosion resistance requirements. Steel, which is heavier than aluminum but stronger, is suitable for applications requiring high strength and abrasion resistance. Learn More
Author
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.