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Introduction to Aluminum CNC Machining
Aluminum is a versatile material metal commonly used in various industries for different purposes. It is soft, non-magnetic, and ductile in its purest form and you can alloy it with various elements, including magnesium, copper, and manganese, to create different alloys with varying improved properties.
Aluminum CNC machining is amongst the top machining operations in terms of frequency of execution due to the material’s remarkable machinability. Manufacturers rely on aluminum CNC machining to make different precision aluminum parts that meet the intended applications’ requirements. The process involves using CNC routers to shape aluminum material into preferred shapes and dimensions.
Benefits of Aluminum that Make it Ideal for CNC Machining
Aluminum alloys offer varying properties that make them ideal for CNC machining applications. This section discusses the benefits of aluminum in CNC machining:
Strength-to-Weight Ratio
Aluminum is about one-third of steel’s density, making it a relatively light metal. Aluminum exhibits remarkably high strength even though has low weight. Hence, this high strength-to-weight ratio makes aluminum ideal for CNC machining automotive and aerospace applications.
Machinability
It is easier to form and machine aluminum alloys than other metals. You can use machine tools to easily and quickly cut aluminum since it is soft and chips easily. Aluminum alloys are less expensive and require minimal power to machine.
The excellent machinability of aluminum alloys helps mitigate deformation risks during machining. Hence, it ensures higher accuracy in machining custom aluminum parts since CNC machines can easily achieve tight tolerances.
Corrosion Resistance
Aluminum exhibits natural corrosion resistance in different atmospheric conditions. However, you can anodize your aluminum machined parts to enhance these properties. Also, it would help to understand different aluminum grades have varying resistance to corrosion. Nevertheless, the most widely used CNC machined grades have excellent corrosion resistance.
Electrical Conductivity
Pure aluminum possesses electrical conductivity of about 37.7 million Siemens per meter at room temperature. Aluminum alloys provide electrical conductivity for their parts, making them applicable for electrical components, even though they may exhibit lower conductivities than pure aluminum. However, aluminum alloys would be unsuitable if electrical conductivity is not a primary requirement of your machined part.
Custom Finishing
Aluminum machined parts are compatible with extensive surface finishes such as chromate conversion coating, anodizing, powder coating, and painting to achieve the preferred custom appearance for your project.
Recyclability
CNC machining processes create constant chip load, considered waste materials since it’s a subtractive process. However, aluminum is highly recyclable; as a result, it requires cost, effort, and minimal energy to recycle.
Moreover, this attribute makes aluminum suitable for manufacturers who want to recover expenditure or lower material wastage. Likewise, the recyclability of aluminum makes it a more environmentally friendly metal to machine.
Aluminum Grades for CNC Machining
| Series | Main Alloying Element | Principal Characteristics | Typical Applications |
|---|---|---|---|
| 1000 | 99% Aluminum | Highly corrosion resistant, excellent workability, electrical conductivity | Chemical equipment, reflectors, food industry containers |
| 2000 | Copper | High strength, good machinability, limited corrosion resistance | Aircraft structures, rivets, truck wheels, screw machine products |
| 3000 | Manganese | Good workability, moderate strength, excellent corrosion resistance | Cookware, automotive trim, roofing, siding |
| 4000 | Silicon | Good flow characteristics, lower melting point | Brazing alloys, welding wires |
| 5000 | Magnesium | Good corrosion resistance, moderate-to-high strength, good weldability | Marine applications, tankers, structural applications, pressure vessels |
| 6000 | Magnesium & Silicon | Medium strength, good corrosion resistance, good formability, weldability | Architectural extrusions, frames, railings, automotive parts |
| 7000 | Zinc | Very high strength, less corrosion resistance than 2000 series | Aircraft structures, sporting equipment, automotive parts |
Generally, pure aluminum material contains 99 to 99.6% aluminum elements, with other alloying elements, including zinc, magnesium, silicon, manganese, and copper, making up the remaining percent. This section discusses the common aluminum alloys based on the primary alloying element:
1000 Series
Aluminum 1xxx alloys comprise the highest pure aluminum content, with about 99% aluminum by weight. There is no particular alloying element; most of these alloys are almost pure aluminum. For instance, aluminum 1199 contains 99.99% aluminum by weight, which is ideal for making foil. Although these grades are the softest, you can harden them to make them stronger when continuously deformed.
2000 Series
The main alloying element of the 2xxx series of aluminum is copper. These are heat-treatable aluminum alloys made almost as hard and strong as steel with precipitation hardening. This heat treatment process increases yield strength in these aluminum alloys by heating the aluminum material to make precipitates of the other metals emerge from the metal.
Aluminum alloys in this category exhibit lower corrosion resistance. Nevertheless, aluminum 2024 comprises manganese and magnesium, making it corrosion-resistant. Hence, it is a commonly used material in aerospace CNC machining.
3000 Series
The 3xxx series of aluminum has manganese as its principal alloying element. However, you can harden these aluminum alloys to achieve desirable hardness levels since these grades of aluminum cannot be heat-treated. For instance, the aluminum 3004 contains magnesium, and it is among the commonly used aluminum alloys in making beverage cans. Similarly, the 3003 is a general-purpose alloy with vast applications.
4000 Series
Silicon is the major alloying element of the 4000 series of aluminum. The silicon content results in a low melting point of 4xxx aluminum grades. Aluminum 4047 is perfect for sheet and cladding in construction, while aluminum 4043 is ideal as filler rod material for welding 6000 series alloys.
5000 Series
The 5000 series has magnesium as its primary alloying element. These aluminum grades exhibit good resistance to corrosion. Therefore, they are well-suited for marine or other applications that expose aluminum to extreme elements. However, aluminum 5083 is an alloy commonly employed in marine applications.
6000 Series
The 6xxx series comprises silicon and magnesium as its major alloying elements. You can easily machine the 6000 series aluminum alloys, which are precipitation-hardened. Most aluminum alloys in this series, especially the 6061, have high applications and good corrosion resistance. It is widely used for structural and aerospace applications.
7000 Series
Zinc and sometimes magnesium, chromium, and copper are the major alloying elements for these aluminum alloys. These aluminum grades can possess peak strength when subjected to precipitation hardening. 7xxx grades have typical applications in the aerospace industry due to their high strength.
7075 is a popular grade with poor corrosion resistance than other aluminum alloys, even though it has more excellent resistance than 2xxx aluminum alloys. This alloy is universally applicable even though it is mainly utilized in aerospace parts machining.
8000 Series
The 8000 series encompasses aluminum alloys that don’t belong to any of the categories discussed earlier. These aluminum alloys can contain several other elements, such as lithium and iron. For instance, 8176 aluminum comprises 0.1% silicon and 0.6% iron by weight, and its typical application includes electrical wire.
Best Aluminum Grades for CNC Processes
Although different grades of aluminum are suitable for various CNC machining applications, some exhibit more outstanding properties than others. This section discusses the best aluminum alloy for CNC processes
6061 Aluminum Alloy
The aluminum 6061 is widely embraced in general manufacturing, architecture, consumer goods, and aerospace industries due to its versatility and outstanding weldability. This medium-strength alloy is heat-treatable and offers high corrosion resistance. You can machine this aluminum alloy with different techniques and exhibit exceptional workability in the annealed condition.
7075 Aluminum Alloy
Aluminum 7075 is one of the aluminum alloys with the highest strength. This high-strength alloy exhibits good fatigue resistance, which is ideal for making parts for high-stress applications. Hence, the 7075 aluminum is the most popular aluminum alloy in aerospace applications. It also has aerospace-grade strength, which makes it ideal for making complex parts.
Cost of Aluminum CNC Machining
The cost of CNC machining of aluminum consists of the following major aspects.
- Raw material prices
- Machining hours
- labor costs
- tool wear and tear
- product complexity
The cost of aluminum has a definite advantage over CNC machining of other metals such as steel. Aluminum’s raw material costs are typically lower than steel, which is reflected in the overall price. Aluminum is softer, making it easier and quicker to machining—typically taking only 1/2 to 1/4 the time required for steel parts. This efficiency cuts labor costs and accelerates production.
However, the abrasive nature of aluminum may result in more frequent tool changes, which may increase tooling costs. Conversely, steel is more ductile and requires more time and effort to machine, thereby increasing operating costs. In addition, machining steel typically increases tool wear and energy consumption. Despite these challenges, the longevity and durability of steel may be necessary in some applications.
Common Aluminum CNC Machining Techniques
This section discusses the different machining processes for aluminum alloys.
CNC Milling
CNC milling is an automated process that often fabricates aluminum parts by rotating a multi-point cutting tool along its axis while the workpiece remains fixed along its axis. The CNC router gradually removes material from the aluminum workpiece at a controlled pace, which can occur along multiple axes. You can achieve high tolerances when milling aluminum.
CNC Drilling
CNC drilling is a common technique used in creating holes in aluminum workpieces. It involves using a multi-point rotating cutting tool of a specific size to move in a straight line perpendicular to the material that needs drilling. This process is suitable for machining products that require assembly or accommodate screws and bolts.
CNC Turning
Aluminum CNC turning involves rotating the workpiece while the single-point cutting tool remains stationary along its axis. Either the cutting tool or the workpiece performs the feed motion against the other, depending on the machine to remove the material. The raw material rotates at high speed while the turning center removes material to create the desired shape.
Key Challenges in Aluminum CNC Machining
Manufacturers and product engineers often encounter setbacks in aluminum CNC machining regardless of its remarkable machinability. This section discusses some of these challenges along with possible solutions:
Aluminum’s Malleability
Aluminum’s high malleability can result in complications like poor surface finish, burrs, and chip formation during aluminum CNC machining. Built-up edges often occur as the material sticks to the cutting tool. Consequently, it results in reduced tool life.
Solution: You must use the right cutting tools specifically designed for machining aluminum, including carbide or polycrystalline diamond (PCD) tools. You can also use cutting fluids to efficiently dissipate heat and reduce friction, ensuring superior surface finishes. You may need to secure the aluminum workpiece to minimize deflection and chatter during machining.
Thermal Issues During Machining
Aluminum alloys dissipate heat faster during CNC machining because of their high thermal conductivity. Consequently, this can lead to workpiece thermal deformation, low machining accuracy, and tool wear.
Solution: Use a high-pressure coolant system in aluminum CNC machining to mitigate overheating. Likewise, you can reduce cutting speed to ensure low heat generation, preventing the thermal expansion of the workpiece.
Wear and Tear of Machining Tools
The presence of silicon in some aluminum alloys may make aluminum machining abrasive. As a result, you may experience rapid tool wear and consistent tool changes during aluminum CNC machining.
Solution: It is advisable to use high-quality tools with extraordinary hardness and toughness to mitigate frequent tool changes while increasing productivity. Also, coatings such as TiAlN (Titanium Aluminum Nitride) or TiCN (Titanium Carbo-Nitride) ensure improved tool life in high-temperature operations.
More importantly, use tools with sharp cutting edges and right rake angles to reduce friction. You can also check the cutting tools frequently for signs of wear and replace worn tools immediately to prevent workpiece damage.
Applications of Aluminum CNC Machined Parts
Aluminum CNC machined parts pack outstanding qualities ideal for different industries and purposes. Here are some of the typical applications of these parts:
Aerospace Innovations
Aluminum CNC parts are ideal for structural parts like engine components, airframe components, and landing gear in the aerospace industry since aluminum alloys offer good mechanical properties. Aluminum offers excellent strength-to-weight ratio and low weight, making it a widely used material in reducing aircraft weight.
Aluminum CNC machining helps to meet the stringent quality standards for precision and reliability in the aerospace industry. CNC-machined aluminum parts play pivotal roles in producing aero-structures like wing panels and fuselage sections.
Automotive Engineering
The automotive industry has benefitted immensely from the outstanding properties of aluminum in making different automotive parts and systems. Manufacturers and engineers in the automotive industry use aluminum CNC machined parts in automotive engineering, most especially in engine components, suspension systems, transmission housing, and electric vehicle components.
The lightweight, durability, and strength of aluminum alloys make CNC-machined aluminum parts ideal for reducing overall vehicle weight and ensuring the durability of vehicles.
Consumer Electronics
Aluminum CNC machined parts are widely embraced in producing a broad range of consumer electronics products, including laptops, audio equipment, smartphones and tablets, and camera parts. Aluminum is suitable for making casings of laptops, smartphones, and tablets because it provides a smooth and lightweight design, protecting the internal components of electronic devices.
Besides, high-end audio equipment such as amplifiers, headphones, and speaker enclosures often house aluminum CNC machined parts. Aluminum is commonly used in this application since it can dampen vibrations. Also, aluminum CNC machined parts offer the desired strength and can dissipate heat in devices like cameras.
How to Choose the Right Partner for Aluminum CNC Machining
Having gone through this article, you should have realized that aluminum offers many desirable benefits and properties with CNC machining. However, choosing the ideal manufacturing partner to handle your aluminum CNC machining project is essential.
As such, it is advisable to partner with a CNC shop with the right machining tools to fabricate quality aluminum parts with high accuracy. Additionally, the machining service provider must have experience manufacturing aluminum parts and all the required quality certifications to ensure your parts meet the required quality standards.
However, it is not advisable to partner with a CNC machine shop without the required quality certification and CNC machines to achieve the desired precision and accuracy. Similarly, you should not outsource your custom aluminum parts to a partner with little or no experience handling such projects!
AT-Machining is here for you whenever you need aluminum prototypes or custom aluminum machined parts for your applications. We are a leading CNC machining expert with a team of qualified and experienced machinists and engineers. We leverage our CNC aluminum machining expertise to offer CNC aluminum parts with tight tolerances and faster cycle time. Contact us now to get a quote for your project!
Conclusion
Aluminum CNC machining is a widely embraced product manufacturing process thanks to the unequaled potential of aluminum alloys. The alloys of aluminum have further improved aluminum’s characteristics and properties, making CNC aluminum machining an ideal manufacturing process.
This guide has discussed the typical aluminum grades for CNC machining. Nevertheless, it is crucial to understand everything about CNC aluminum machining and identify the ideal aluminum alloy for your project to harness the full potential of aluminum in CNC machining.
