Aluminum alloy is one of the most popular nonferrous metal structural materials, which has been widely used in aviation, aerospace, automobile, machinery manufacturing, ship and chemical industry. With the rapid development of industrial economy, the demand for welded structural parts of aluminum alloy is increasing day by day. Nowadays, aluminum alloy can be the most widely used alloy. When it comes to CNC machined aluminum parts , aluminum alloy is also the most commonly used metal material as the material is easy to get and easy to machined. Thus in the rapid prototype manufacturing industry, aluminum parts could be seen everywhere.
The Characteristics of Aluminum
The density of aluminum alloy is low among metal materials. But its intensity is higher compared to other alloys, which is closed to or exceed high grade steel. As it has a good plasticity, aluminum can usually be machined into many sorts of ALUMINIUMPROFILES. With the characteristic of excellent electricity and thermal conductivity, corrosion resistance, aluminum is used very commonly in every industry, which is next only to steel and is the most common used material for machining aluminum parts. Some aluminum alloys can go through heat treatment to have good mechanical properties, physical properties and corrosion resistance. Hard aluminum alloy (AI – Cu – Mg), generally contains a small amount of Mg. It is characterized by high hardness but poor plasticity. Super hard aluminum belongs to Al-Cu -Mg-Zn series, which can be strengthened by heat treatment. It is the aluminum alloy with the highest strength at room temperature, but poor corrosion resistance and fast softening at high temperature. Forged aluminum alloy is mainly Al-Zn-Mg-Si series alloy, although a variety of elements are added, but the content is small, so it has excellent thermoplastic and is suitable for forging. Forged aluminum is also called forged aluminum alloy.
The Classification of Aluminum Alloy
Aluminum alloys could be divided into nine series, from class one to class nine.
Series 1: 1050, 1060 and 1100. The 1000-series is one of the most aluminum-containing series of all series. Its purity can reach 99.00% above. As it does not contain other metal elements, the production process is relatively simple with a relatively cheap price. Currently, most of the 1050 and 1060 series are in circulation on the market. 1000 series aluminum plate determine the minimum aluminum content of this series. For example, the last two Arabic numerals of 1050 series is 50. According to the international brand naming principle, the aluminum content must reach 99.5% above for qualified products.
Series 2: 2024, 2A16 (LY16), 2A02 (LY6). 2000 series aluminum plate is characterized by high hardness, in which the content of copper is the highest, about 3-5%. The 2000 series aluminum rods are the aviation grade aluminum and not often used in conventional industry.
Series 3: 3000 series aluminum alloy is mainly represented by 3003 and 3A21. China 3000 series aluminum plate production process is relatively excellent. The 3000 series aluminum bar is content of manganese. With a content between 1.0 and 1.5, it is a series with better anti-rust function.
Series 4: 4000 series aluminum bars are represented as 4A01. 4000 series aluminum plates belong to the series with high silicon content. The silicon is usually between 4.5 and 6.0%. It is a kind of building, forging and welding grade materials for mechanical parts. This series has a low melting point and is of good corrosion resistance, heat resistance and wear resistance.
Series 5: 5052, 5005, 5083, 5A05 series. The 5000 series aluminum bars belong to the more commonly used alloy aluminum plate series. It is also known as aluminum magnesium alloy. The main characteristics are low density, high tensile strength, high elongation, good fatigue strength. But it could not do heat treatment for strengthening. The weight of al-mg alloy in the same volume is lower than other series. It is also widely used in the conventional industry. 5000 series aluminum plate is one of the mature aluminum plate series in China.
Series 6: 6061 mainly contains magnesium and silicon, so it concentrates the advantages of 4000 series and 5000 series. Good serviceability, easy coating and machining. Many customer choose this series aluminum for the aluminum machined parts.
Series 7: 7075 mainly containing zinc elements. It is also belong to aviation series. It is aluminum that contents the element of magnesium, zinc and copper. This series of aluminum is heatable. As it belongs to super hard aluminum alloy, it has good wear resistance. It also has good welding property, but poor corrosion resistance. In prototype manufacturing, this series is also the most common use for customer’s aluminum machined parts.
Series 8: The 8000 series aluminum alloy is more commonly used as 8011. It belongs to other series, and is mostly use for aluminum foil.
Series 9: 9000 series aluminum alloy is a standby alloy.
The Surface Finish of CNC Aluminum Parts – Anodized
Anodic oxidation: a uniform, dense oxide layer can be formed on the surface of the aluminum parts. This film can make the product surface harder, 200-300(HV), if aluminum CNC parts can do hard anode oxidation, product’s surface hardness could reach 400-1200 HV. Therefore hard anode oxidation is the necessary surface treatment for the machining aluminum parts of oil cylinder, transmission. In addition, the products which have go through the anodizing have good wear resistance, which make it the necessary process for aviation, aerospace industry. There is difference between Anodic oxidation and hard anodic oxidation. Anodic oxidation could color the parts and it decorative capacity is better than hard anodized. Anodic oxidation is very strict with the material, as different materials’ surface has different adornment effect. Usually the materials used are 6061,6063,7075,2024, etc., among which, 2024 has a relatively poor effect.
The Application of Aluminum Parts
Below is the application of some series of aluminum alloy.
1100 is used for processing parts and components that require good formability and high corrosion resistance but do not require high strength, such as chemical products, food industry equipment and storage containers, thin plates, work-pieces, deep drawing or spinning concave vessels, welded parts, heat exchangers, printed plates, nameplates, reflectors.
3004 is usually used for can body that requires parts with higher strength than 3003 alloy, chemical product production and storage device, sheet work-piece, construction work-piece, construction tools and various lamp parts.
6061 is suitable for machining CNC parts that requires various industrial structures with certain strength, weldability and high corrosion resistance, such as tubes, rods, shaped materials and plates for manufacturing trucks, tower buildings, ships, trams, fixtures, mechanical parts and precision machining.
7075 is widely is aviation and aerospace industry. These kind of CNC machined part have a good feature of strength, corrosion resistance and fatigue resistance.