Aluminum Machining: processes, benefits, methods,features

What is the Aluminium CNC Machining Processes?

You can machine aluminium by a number of the CNC machining processes available today. Some of these processes are as follows.

CNC Turning:

In CNC turning operations, the workpiece rotates, while the single-point cutting tool stays stationary along its axis. Depending on the machine, either the workpiece or the cutting tool carries out feed motion against the other in order to achieve material removal.

CNC Milling:

CNC Milling operations are the most commonly used in machining aluminium parts. These operations involve the rotation of a multi-point cutting along its axis, while the workpiece stays stationary along its own axis. Cutting action and subsequently material removal is achieved by the feed motion of either the workpiece, the cutting tool, or both of them combined. This motion can be carried out along multiple axes.

Pocketing:

Also known as pocket milling, pocketing is a form of CNC milling in which a hollow pocket is machined in a part.

Facing:

Facing in machining involves creating a flat cross-sectional area on the surface of a workpiece through either face turning or face milling.

CNC Drilling:

CNC Drilling is the process of making a hole in a workpiece. In this operation, a multi-point rotating cutting tool of a particular size move in a straight line perpendicular to the surface to be drilled, thereby effectively creating a hole.

What Are the Most Critical Quality Control Measures for Ensuring the Dimensional Accuracy and Consistency of Machined Aluminum Parts?

Ensuring the dimensional accuracy and consistency of machined aluminum parts is crucial for meeting specifications and maintaining high quality. As an experienced Supplier Quality Engineer (SQE) in the field of aluminum machining, I can highlight several critical quality control measures:

Precision Machining Processes:

Calibration: Regularly calibrate CNC machines and tools to ensure precision. Any deviation can lead to dimensional inaccuracies.

Tool Maintenance: Keep cutting tools sharp and in good condition to prevent dimensional variations and surface finish issues.

First Article Inspection (FAI):

Conduct a thorough first article inspection to verify that the initial parts produced meet all specified dimensions and tolerances. This step helps identify and correct any potential issues early in the production process.

In-Process Inspection:

Regular Checks: Perform regular dimensional checks during the machining process using precision measuring instruments such as calipers, micrometers, and coordinate measuring machines (CMMs).

SPC (Statistical Process Control): Implement SPC techniques to monitor and control the machining process. Use control charts to track critical dimensions and detect trends that might indicate potential issues.

Post-Process Inspection:

CMM Inspection: Utilize coordinate measuring machines for detailed inspection of finished parts to verify that all dimensions and tolerances are within specification.

Surface Finish Measurement: Measure surface finish using profilometers to ensure the required surface texture is achieved.

Quality Management Systems:

ISO Certification: Adhere to ISO 9001 or other relevant quality management standards to ensure systematic and consistent quality control practices.

What Are the Latest Advancements in Inspection Technologies for Aluminum Machining?

The field of inspection technologies has seen significant advancements, enhancing the ability to ensure the quality of machined aluminum parts. Some of the latest innovations include:

In-Line Metrology:

Real-Time Inspection: In-line metrology systems allow for real-time inspection of parts directly on the production line. These systems use laser scanners, vision systems, and other sensors to measure dimensions and detect defects without interrupting the manufacturing process.

Automated Feedback: Integrating in-line metrology with CNC machines enables automatic adjustments based on real-time data, ensuring continuous dimensional accuracy.

Automated Defect Detection:

Machine Vision Systems: Advanced machine vision systems use high-resolution cameras and AI algorithms to detect surface defects, dimensional deviations, and other quality issues. These systems can inspect parts at high speed and provide immediate feedback.

3D Scanning: 3D scanning technologies, such as structured light and laser scanners, create detailed 3D models of machined parts. These models are compared to CAD designs to identify any discrepancies.

Non-Contact Measurement:

Laser Interferometry: Laser interferometry provides highly accurate, non-contact measurement of dimensions and surface profiles. This technology is especially useful for inspecting complex geometries and delicate parts.

Optical CMMs: Optical coordinate measuring machines use light and cameras to perform precise measurements without physical contact, reducing the risk of part deformation.

Data Analytics and AI:

Predictive Maintenance: Using AI and data analytics, manufacturers can predict when tools or machines are likely to fail or go out of tolerance, allowing for proactive maintenance and reducing downtime.

Quality Prediction: Machine learning algorithms analyze historical data to predict potential quality issues, enabling preventive actions to be taken before defects occur.

By incorporating these advanced inspection technologies, we can significantly enhance the accuracy, consistency, and efficiency of quality control processes for machined aluminum parts.

What’s the Popular Aluminum Alloys for CNC Machining?

From our experience at Welle, the following 5 aluminium grades are one of the most often used for CNC machining.

EN AW-2007 / 3.1645 / AlCuMgPb

Alternative designations: 3.1645; EN 573-3; AlCu4PbMgMn.

This aluminium alloy has copper as its main alloying element (4-5%) of copper. It is a short-chipped alloy that is durable, light, highly functional, and has the same high mechanical properties as AW 2030. It is also suitable for threading, heat treatment, and high-speed machining. All these properties make EN AW 2007 widely used in the production of machine parts, bolts, rivets nuts, screws, and threaded bars. However, this aluminium grade has low weldability and low corrosion resistance; therefore it is recommended to carry out protective anodising after part machining.

EN AW-5083 / 3.3547 / Al-Mg4,5Mn

Alternative designations: 3.3547; Alloy 5083; EN 573-3; UNS A95083; ASTM B209; AlMg4.5Mn0.7

AW 5083 is renowned for its excellent performance in severe environments. It contains magnesium and small traces of chromium and manganese. This grade has very high resistance to corrosion in both chemical and marine environments. Of all the non-heat treatable alloys, AW 5080 has the highest strength; a property which it retains even after welding. While this alloy should not be used in applications with temperatures higher than 65°C, it excels in low temperature applications.

Due to its set of desirable properties, AW 5080 is used in numerous applications including cryogenic equipment, marine applications, pressure equipment, chemical applications, welded constructions, and vehicle bodies.

EN AW 5754 / 3.3535 / Al-Mg3

Alternative designations: 3.3535; Alloy 5754; EN 573-3; U21NS A95754; ASTM B 209; Al-Mg3.

Being a wrought aluminium-magnesium alloy with the highest % of aluminium, AW 5754 can be rolled, forged, and extruded. It is also non heat-treatable and can be cold-worked to increase its strength, but at a lower ductility. In addition, this alloy has excellent resistance to corrosion and has high strength. Considering these properties, it is understandable that AW 5754 is one of the most popular CNC machined aluminium grades. It is typically used in welded structures, flooring applications, fishing equipment, vehicle bodies, food processing, and rivets.

EN AW-6060 / 3.3206 / Al-MgSi

Alternative designations: 3.3206; ISO 6361; UNS A96060; ASTM B 221; AlMgSi0,5

This is a magnesium and silicon-containing wrought aluminium alloy. It is heat-treatable and has average strength, good weldability, and good formability. It is also highly resistant to corrosion; a property which can be improved even further through anodising. EN AW 6060 is often used in construction, food processing, medical equipment, and automotive engineering.

EN AW-7075 / 3.4365 / Al-Zn6MgCu

Alternative designations: 3.4365; UNS A96082; H30; Al-Zn6MgCu.

Zinc is the primary alloying element in this grade of aluminium. Although EN AW 7075 has average machinability, poor cold forming properties, and is not suitable for both welding and soldering; it has a high strength-to-density ratio, excellent resistance to atmospheric and marine environments, and strength comparable to some steel alloys. This alloy is employed in a very wide range of applications including hang glider and bicycle frames, rock climbing equipment, weaponry, and mold tool manufacturing.

EN AW-6061 / 3.3211 / Al-Mg1SiCu

Alternative designations: 3.3211, UNS A96061, A6061, Al-Mg1SiCu.

This alloy contains magnesium and silicon as its major alloying elements with trace amounts of copper. With a tensile strength of 180Mpa, this is a high strength alloy and is very suitable for highly loaded structures such as scaffolds, rail coaches, machine and aerospace parts.

EN AW-6082 / 3.2315 / Al-Si1Mg

Alternative designations: 3.2315, UNS A96082, A-SGM0,7, Al-Si1Mg.

Typically formed by rolling and extrusion, this alloy has medium strength with very good weldability and thermal conductivity. It has high stress corrosion cracking resistance. It has a tensile strength that ranges from 140 – 330MPa. It is heavily employed in offshore construction and containers.

What’s the Post-machining Processes of Aluminum Machined Parts?

After machining an aluminium part, there are certain processes that you can carry out to enhance the physical, mechanical, and aesthetic features of the part. The most widespread processes are as follows.

Bead and Sand Blasting:

Bead blasting is a finishing process for aesthetic purposes. In this process, the machined part is blasted with tiny glass beads using a highly pressurised air gun, effective removing material and ensuring a smooth surface. It gives aluminium a satin or matte finish. The main process parameters for bead blasting are the size of the glass beads and the amount of air pressure used. Only use this process when the dimensional tolerances of a part are not critical.

Other finishing processes include polishing and painting.

Coating:

This involves coating an aluminium part with another material such as zinc, nickel, and chrome. This is done to improve the parts processes and may be achieved through electrochemical processes.

Anodising:

Anodising is an electrochemical process in which an aluminium part is dipped in a solution of diluted sulphuric acid, and an electric voltage is applied across the cathode and anode. This process effectively converts the exposed surfaces of the part into a hard, electrically non-reactive aluminium oxide coating. The density and thickness of the coating created is dependent on the consistency of the solution, the anodising time, and the electric current. You may also carry out anodisation to colour a part.

Powder Coating:

The powder coating process involves coating a part with colours polymer powder, using an electrostatic spray gun. The part is then left to cure at a temperature of 200°C. Powder coating improves strength and resistance to wear, corrosion, and impact.

Heat Treatment:

Parts made from heat-treatable aluminium alloys may undergo heat treatment to improve their mechanical properties.

Where of the Applications of CNC Machined Aluminium Parts?

As stated earlier, aluminium alloys have a number of desirable properties. Hence, CNC-machined aluminium parts are indispensable in several industries, including the following:

Aerospace: due to its high strength-to-weight ratio, several aircraft fittings are made from machined aluminium;
Automotive: similar to the aerospace industry, several parts such as shafts and other components in the automotive industry are made from aluminium;
Electrical: having high electrical conductivities, CNC machined aluminium parts are often used as electronic components in electrical appliances;
Food/Pharmaceutical: because they do not react with most organic substances, aluminium parts play important roles in the food and pharmaceutical industries;
Sports: aluminium is often used to make sports equipment such as baseball bats and sport whistles;
Cryogenics: aluminium’s ability to retain its mechanical properties at sub-zero temperatures, makes aluminium parts desirable for cryogenic applications.