Aluminum is the most common metal on the planet, so it makes sense that it would be widely used in manufacturing and part production. But is it used so much just because it’s easy to find? Of course not! Aluminum is even superior to steel when it comes to strength-to-weight ratio. The different grades of aluminum alloys are flexible and easy to process. They are therefore used in a wide range of different applications.
As mentioned earlier, there are different grades of aluminum, each with its own properties. Therefore, this article will serve as a guide to choosing a material. First, it will describe the different grades of aluminum metal, their uses, and how they work. In addition, it will describe the different types of sample machining that can be done with each grade of aluminum. Scroll down to the end to learn how to quickly select the best grade of metal for manufacturing parts.
Table of Contents
Properties of Aluminum
Aluminum alloys are composed primarily of aluminum, but copper, zinc, magnesium, and silicon are also added to enhance certain specific properties. The different grades of aluminum alloys are based on their chemical makeup, and each grade has its own advantages for different uses. The type of aluminum alloy used is very important for rapid prototyping. This is because it affects the effectiveness of the final prototype, its cost, and how well it matches the requirements.
- Physical Properties. Pure aluminum is a very soft metal. However, aluminum alloy is a very strong metal. Because of its relatively low density, aluminum alloys have the best strength-to-weight ratio of any metal. Aluminum alloys are also resistant to cold weather and corrosion.
- Thermal and Electrical Properties. Aluminum is a good material for manufacturing heat exchange components in automobiles because of its high thermal conductivity. In addition, different aluminum alloys can both conduct and resist electricity. Therefore, some aluminum alloys can be used to make electrical wires, while others are used where resistivity is required.
- Mechanical Properties. The tensile strength of aluminum can be high or low, depending on the grade of aluminum. Some aluminum has a tensile strength as high as 100ksi, while others are as low as 1.5ksi.
- Reflectance. If aluminum is polished, it can be made to have a very bright surface. As a result, aluminum alloys are excellent at reflecting radiant energy, a quality desired in many lamps and decorative accessories.
Advantages and Disadvantages of Aluminum for Machining Purposes
Aluminum is a very useful metal that can be used in many ways. Some of its properties make it very popular for machining. However, just like all other good things, aluminum has advantages and disadvantages.
Advantages of Aluminum in Machining
Corrosion Resistance
Aluminum will not rust or corrode. A protective layer of aluminum oxide quickly forms on the surface of aluminum alloys, which helps them resist corrosion from the weather. If aluminum is given a good surface treatment and regularly maintained, it will not corrode even in the harshest environments. Due to this property of aluminum, it can be used to manufacture components that are exposed to harsh environmental conditions.
Low Cost
Aluminum does not have the lowest cost of production, but when its advantages are taken into account, the cost is quite low. This means that it is cheaper than other metals with the same benefits and is the best choice in most cases.
Strong and Lightweight
Aluminum is the metal with the best strength-to-weight ratio and is therefore very strong. Because of this, it can be used where extra strength is needed. The high strength-to-weight ratio indicates that this strength does not come at the cost of weight. Aluminum alloys are used for mechanical parts that need to be as light as possible but still very strong. This is because aluminum alloys are almost three times as dense as steel.
Recyclability
Aluminum can be recycled over and over again. Aluminum is also easier to recycle than many other metals, making it a good choice for the environment.
Can Be Used for Rapid Mold-making
A production method called rapid tooling has become popular. This is because it saves costs and reduces lead times. Aluminum is a material commonly used for rapid mold manufacturing. Aluminum alloys are easy to form and do not cost much. The reasons why manufacturers favor it are obvious.
No Need for Excessive Maintenance
Aluminum parts maintain their quality and performance even under the worst conditions. So, aluminum parts are therefore a good choice for parts that are difficult to maintain on a regular basis. In addition, aluminum can also withstand extremely low temperatures without breaking or cracking.
Customizable
Because aluminum is easy to work with, it can be molded into almost any shape. Aluminum not only paints well, but its surface holds most finishes well.
Disadvantages of Aluminum in Machining
- Easy Conductivity. This is both an advantage and a disadvantage, depending on where it is used. However, it means that aluminum alloys cannot be used in certain applications where electrical resistance is important.
- Low Melting Point. Since aluminum has a low melting point, it is not suitable for use in places where heat is high. However, there are some aluminum alloys that can solve this problem.
Aluminum Alloy Grades
There are two main types of aluminum alloys: wrought alloys and cast alloys.
Forged Alloys
For the most part, these types of aluminum alloys are stronger than cast metals. They also use the four-digit method but without a decimal point. The first digit indicates the primary alloying element, just like the cast iron name. If it’s not zero, the second number indicates that the alloy has changed, and the last two numbers tell you which alloy in the series it is. Below is a list of the seven series of forging alloys:
1xxx Series
These aluminum alloys are sometimes called “pure aluminum” because they must contain at least 99% aluminum. They are not very strong, but machinists choose to use them. This is because they do not rust and are well-energized. It is also possible to weld them, but the machinist must be very careful as they have a very low melting point.
2xxx Series
Copper is the main element that makes up this series. The best method of treating these metals is the solid solution heat treatment process. As a result, the alloys of this series are very strong and hard but are not as resistant to corrosion as the other series. For this reason, when it is necessary to use these alloys in corrosion-prone areas, the machinist usually gives them a paint or coating of non-rusting metal.
3xxx Series
Manganese is the main element that makes these alloys. They are not very strong but have very good heat and rust resistance. This makes them ideal for use as cooking tools. These aluminum series are commonly used in power plants and automobiles for exchange parts.
4xxx Series
The 4xxx series alloys are used as filler metals in welding due to their low melting point. In these series, the metal is made from a mixture of aluminum and silicon.
5xxx Series
These aluminum alloys cannot be heated, but they have the greatest tensile strength. Its main alloying element is magnesium. As a result, they do not rust and are easy to weld, making them a good choice for naval vehicles and equipment components. In addition, their ultimate tensile strength is between 18ksi and 51ksi.
6xxx Series
The alloys of this series have good corrosion resistance. Their maximum tensile strength is between 18ksi and 58ksi. Magnesium and silicon are the main alloying elements in this combination of golds. These alloys are used for coatings on corrosion-prone metals. These metals also contain magnesium and silicon, resulting in magnesium silicide. This material can be heated in solution, thus making it stronger.
7xxx Series
Zinc is the primary alloying element in these aluminum alloys. They have the highest tensile strength of all aluminum alloys with tensile strengths ranging from 32 to 88 ksi. This type of metal is used by machinists to make tools and gear parts that are subjected to higher stresses, such as sports and aerospace gears. In addition to aluminum, other metals such as copper can be added to change the way wrought aluminum works.
Cast alloys
These alloys can be treated either with or without heat. They use the four-digit method with a decimal point before the last digit. The first number tells us the main elements that make up the metal. The next two numbers indicate the type of material and the number after the decimal point indicates whether it is an ingot or a casting.
Differences Between Wrought and Cast Alloys
- The tensile strength of cast alloys is usually lower than that of wrought alloys because of the difficulty of eliminating defects during the casting process.
- For the same weight, cast alloys cost less than wrought alloys.
- Wrought aluminum alloys are easier to machine than cast metals.
- Parts made from wrought aluminum alloys may have a better surface finish than parts made from cast metal.
Common Types of Aluminum
Aluminum 6061-T6
This aluminum alloy belongs to the 6xxx series, as you can tell from the name. Since the second number is zero, we know that this alloy is industrial aluminum with a variety of impurities. The last two numbers, 61, indicate the composition of this metal: 97.9% aluminum, 0.6% silicon, 1.0% magnesium, 0.2% chromium and 0.28% copper.
In this case, T6 indicates solution heat treatment and aging. It takes 40 ksi to stretch 6061 aluminum and 45 ksi to pull it completely apart. This means that the metal is very strong and can be used in building structures. 6061 aluminum will not rust. It is mainly used in the manufacture of automotive parts, heat exchangers, and electronics.
Aluminum 7075-T6
7075 Aluminum’s serial number, 7xxx, indicates that zinc is its main alloying element and this metal has a high tensile strength. It is composed primarily of aluminum (90%), zinc (5.6%), manganese (2.5%), copper (1.6%), and manganese (0.23%). 7075 aluminum is one of the strongest and lightest aluminum alloys. It has a density of 2.81 g/cm3 and a maximum tensile strength of 83 ksi. and of course, the T6 number means that it is heat treated. This metal is commonly used in the manufacture of machine tool gears and aircraft components.
Aluminum 5052
5052 aluminum is quite strong and has excellent corrosion resistance. Since it does not contain copper, it is very useful in saltwater applications. Since this metal belongs to the 5xxx series, it cannot be heated and changed in shape. This alloy is commonly used to make parts for marine tools.
Aluminum 6063
6063 Aluminum, also known as decorative aluminum, is an aluminum alloy made from magnesium and silicon. This alloy is moderately strong and ductile, making it ideal for mold making. It is highly resistant to corrosion and can be used outdoors due to its low copper content and magnesium silicide content. The metal used to make these parts can be used in building materials, pipes and tubes, and furniture.
How to Pick the Right Grade of Aluminum?
You can pick different grades of aluminum. Different grades of aluminum have different properties such as weldability, strength, and corrosion resistance. You can choose the grade of aluminum based on the important features you need for your use case. Before making a decision, you should consider the following points.
Understanding Its Machinability Rating
Ranking the ease of machining an aluminum alloy will give you an idea of how well the alloy will work with a CNC machine. An easy-to-machine aluminum alloy is easy to cut and finish. As a result, it can be used to make complex machine parts. For example, 2011 aluminum is very easy to machine.
Cost and Availability
One of the most important considerations when choosing an aluminum grade for a job is the cost of the alloy. An important step in starting the production process is to find the fit between the target cost and the best properties in that price range. As for the availability of the selected aluminum metal grade, this also depends on its price. Availability is also very important, as rare aluminum alloys that are difficult to obtain may slow down the production process.
How Practical Is It?
This refers to how easy it is to form a particular aluminum alloy. Alloys with high ductility are easy to work with and are mostly used where fatigue resistance is required, such as in aircraft components.
Can It Be Welded?
It is important to consider the weldability of an alloy if the manufactured part needs to be welded to other parts. If welding is required, 3003 aluminum metal is a good choice.
Corrosion Resistance
Where the part will be used determines whether it needs to be corrosion-resistant. For example, parts used in chemical or marine environments must be highly resistant to corrosion.
Can It Be Heat Treated?
Tempering aluminum metal involves heating it to very high or very low temperatures. This process, called heat treatment, makes the aluminum metal stronger. You should note which aluminum alloy series can be heated and which cannot.
How Strong Is It?
How much force an alloy can withstand before it deforms depends on its strength. It is natural to use high-strength aluminum metal for parts that are subjected to high forces.
Depending on the project, you may also need to use steel. So how should you choose the right grade of steel? You can refer to the 304 and 316 stainless steel selection guide for professional help.
Different Uses of Aluminum
Aluminum has many uses in many different industries. The following are some of the areas where aluminum products and parts are commonly used:
Medical Field
Aluminum parts and products are very common in industries that require cleanliness and biocompatibility. Medical tools, such as surgical and orthopedic instruments, are made from different types of aluminum. In addition, aluminum is a major component of some everyday items such as trays and buckets.
Aerospace
The materials used to build airplanes must be both light and strong. Aluminum is well suited for this job because of its lightweight and high strength. Because of this, it can carry the same weight as metals that are stronger than it. Additionally, because aluminum is highly resistant to corrosion, it can help protect planes from damage when they are exposed to harsh weather.
Electrical Industry
Aluminum alloys are always used by companies that manufacture consumer electronics because of their excellent thermal conductivity. Electrical components such as radiators and cooling components for graphics systems use aluminum alloys.
Automotive Industry
The best automobiles should be lightweight, durable, and environmentally friendly. Aluminum alloys can achieve this because it is a light and strong material. Therefore cars can be both flexible and strong. In addition, aluminum car parts can be recycled, which makes cars with aluminum metal parts more environmentally friendly.
Conclusion
Aluminum is a very flexible metal that changes its qualities when mixed with other elements. Different types of aluminum are also suitable for different businesses due to their different properties. However, with the wide variety of aluminum alloys available, it may be difficult for you to decide which aluminum alloy to use in your sample design.
At Yonglihao Machinery, we can help you choose the best material for your machining job. Contact us today and we will help you with your material selection. When selecting materials, it is also important to understand the properties of different alloys and how they perform in different applications. You can refer to 316 and 316L stainless steel in rapid prototyping for more specialized information.