Aluminum is the commonly machined material, due to its excellent machinability, and is thus preferred for manufacturing in the most sectors.
CNC aluminum machining is a primary part of any machine shop because it is relatively easy to shape, and possess some interesting thermal and mechanical properties. This process is used mainly in the production of CNC automotive parts and other CNC parts that are lighter in weight.
Why Choose Aluminum?
It is a relatively soft, ductile, lightweight, durable, and malleable metal and its appearance will depend on the surface roughness of the material ranging from silvery to dull gray.
Its properties are described as;
|Atomic Weight (g/mol)||26.98|
|Melting Point (°C)||660.2|
|Boiling Point (°C)||2480|
|Mean Specific Heat (0-100°C) (cal/g.°C)||0.219|
|Thermal Conductivity (0-100°C) (cal/cms. °C)||0.57|
|Electrical Resistivity at 20°C (Ω.cm)||2.69|
|Modulus of Elasticity (GPa)||68.3|
It can easily be annealed and rolled into the thin foils. It is a good conductor of heat and electricity but not as good as a copper. Aluminum products are commonly used in automotive and aerospace industry.
Not all of the aluminum alloys have same machinability. The choice of aluminum alloy will depend upon you project requirements. They have strong corrosion resistance and sensitive to high temperatures ranging between 200 and 250 °C. They are ranked according to their characteristics.
A few of the metals commonly used to make aluminum alloys include boron, copper, lithium, magnesium, manganese, silicon, tin, and zinc. Following are some alloys of aluminum;
▪ Aluminum 6061: This grade has extraordinary mechanical properties, and weldability. It possess good toughness, medium and high strength, excellent corrosion resistance, and cool anodization. It is commonly used for 5 axis CNC machining.
▪ Aluminum 7075: In it zinc act as the primary alloying element. This grade is known for its excellent fatigue strength and average machinability, but not suitable for welding due to its relatively high cost limits. Oil lubricants are used while performing machining operations and it is excessively used in the aerospace industry.
▪ Aluminum 2024: This alloy is mainly used in military sector due to its mechanical properties, like great wear resistance and high strength. This alloy is non-corrosive and not weldable.
▪ Aluminum 2024: This alloy possesses good corrosion resistance, especially to salt waterand can be easily machined with oil lubricant in hard temper than in annealed form.
CNC Machining Aluminum Prototypes:
Aluminum machined prototype are commonly produced according to a variety of alloys. Aluminum 6061 is the most commonly used alloy in the field of automobile, aerospace, and electronic industries etc. Aluminum alloys have high strength and low density. The CNC machine can manufacture complicated and unique deigns of aluminum prototypes. One of the main reasons engineers choose CNC aluminum machined parts is because the materials are easy to machine.
▪ Economical process
▪ Short production time
▪ Volume goes up the price goes down
▪ Wide range of sizes can be machined
▪ Nominal to high tolerances
While machining aluminum, one of the most common issues is that the material being machined adheres to the edge of cutting tool which results in tool failure. This will reduce the tool life and its cutting ability. Three primary techniques used by tool designers to reduce the occurrence of the built-up edge are;i. Tool material selectionii. Tool coating selectioniii. Tool geometry
Aluminum Comparison with other Metal:
|Aluminum is the most commonly used non-Ferrous Metal with good yield strength and machinability.||Steel possess low yield strength, which make it poor for structural applications.||Nickel is very difficult to machine and work with.||Titanium is difficult to machine and work with due to its physical properties|
|It is non-corrosive||Corrosive than aluminum||Non-corrosive||Less Corrosive than steel|
|Lighter in weight||Heavier in weight||Heavier in weight than steel||Lighter but heavier than aluminum|
|Melting Point is660 oC||Melting Point is1510 oC||Melting Point is1453 oC||Melting Point is1670 oC|
|Density is 2.7 g/cm3||Density is 7.86 g/cm3||Density is 8.9 g/cm3||Density is 4.51 g/cm3|
Surface Treatment for Aluminum Prototypes:
Almost all work parts must be cleaned one or more times during their manufacturing sequence.Processes used to clean the work surfaces are;
▪ Chemical cleaning methods: It uses chemicals to remove unwanted contaminants from the work surface.
▪ Mechanical cleaning: It involves removal of contaminants by various mechanical operations
Surface treatment has been done to prepare surface for subsequent processing, such as a coating application or adhesive bonding and to remove contaminants that might chemically react with the surface. It is also done to enhance appearance and performance of the product.
Before and after surface treatment
Factors in Selecting a Cleaning Method:
✓ Contaminant to be removed
✓ Degree of cleanliness required
✓ Substrate material to be cleaned
✓ Purpose of cleaning
✓ Environmental and safety factors
✓ Size and geometry of the part
✓ Production and cost requirements
Surface treatment for aluminum machined prototypes parts;
i. Oxidation processing: When CNC machined aluminum parts are produced they adopt oxidation processing which enhance the physical characteristics of products and provide nice appearance which promote the overall quality of products.
ii. Electroplating: It is also the most common processing technology for metal processing. After electroplating on the surface of aluminum products, a protective film will be formed on the surface, which can protect the aluminum products from being resistive to the change in its chemical properties when exposed to open air.
iii. Sand blasting: This process is being done to overcome and cover some defects produced by the aluminum alloy while machining and also to meet customer’s appearance requirements.
iv. Polishing: It is the most common method; we can polish the burry surface to make the surface become brighter.
v. Painting Processing: In rapid prototypes machine shop paint processing is excessively used in the production of aluminum prototypes to protect their physical properties. It also improves the appearance of the product.
Application Industry of Aluminum prototypes:
In the modern world, almost every manufacturing industry is in demand of aluminum prototypes. It is mostly used in the industries where weight and strength is the main concern.
Some of the main application industries of aluminum prototypes are;
✓ Aerospace industry
✓ Automobile industry
✓ Electronics industry
✓ Construction industry
✓ Packing and beverages industry
✓ Cookware and utensils industry
✓ CNC rapid manufacturing industry
Outlined above are the basics of the CNC Aluminum machining dealing with the manufacturing of different prototypes using aluminum alloys. In it we discussed about physical and chemical properties of aluminum that how it is the most suitable material for parts manufacturing in different industries and after this we mentioned some aluminum alloys with their properties. CNC machining aluminum prototypes, their advantages and precautions are also taken into consideration. Aluminum is also compared with other metal in sense of machinability, chemical properties and physical properties which shows that aluminum is the most suitable metal where weight and strength is their main concern and at last, we discussed about different surface treatment methods for the parts being produced by aluminum alloys and their applications in different industries.
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