- August 3, 2024
Lightweight metals are important in part manufacturing alongside other materials, especially in the automotive, aerospace, and consumer electronics industries. Here, metals like aluminum and titanium are common because their lightweight properties mean reduced weight and improved aesthetics.
There are several lightweight metals, but only a few are common in part manufacturing. Hence, this article will introduce the common ones, grades, properties, applications, and how to choose the right one.
Why Choose Lightweight Metals for Your Projects?
Lightweight metals offer several advantages in conjunction with their inherent properties, making them a good choice for many projects. Here are a few reasons for you to consider choosing a lightweight metal for your project.
Strength to Weight Ratio
Compared to other materials, lightweight metals are a better option for structural parts because of their high strength-to-weight ratio. For example, a trend in the automotive part manufacturing industry is adopting lightweight materials like aluminum and titanium alloys because of their high strength-to-weight ratio, which helps increase fuel efficiency.
Furthermore, their lower density than other traditional metals makes them suitable for parts requiring less weight.
Corrosion Resistance
Some lightweight metals, like titanium, are corrosion-resistant. Hence, they are suitable for making parts exposed to harsh chemical conditions. For example, the marine industry manufactures parts that come in contact with salt water, and using a corrosion-resistant part will reduce the cost of maintenance and significantly extend part longevity.
Thermal Properties
Lightweight metals like copper and aluminum have high thermal conductivity and low thermal expansion, making them perfect for heat transfer applications. Parts made using these materials do not experience significant thermal stress and distortion.
Sturdy and Durable
Lightweight metals are sturdy and durable even though they have the characteristic of being lightweight. Metals such as titanium and magnesium can function in different environments due to their wear resistance.
Recyclability
Compared to other lightweight materials, lightweight metals are highly recyclable. As a result, there is reduced waste and the production process is sustainable.
Types of Lightweight Metals
Lightweight materials are very important in several industries. Here are a few common metals peculiar to aerospace, automobile, and military industries.
Aluminum and Aluminum Alloy
Aluminum is a lightweight metal with high strength and excellent corrosion resistance. It is alloyed with non-ferrous and other materials for improved mechanical properties or physical attributes. For example, one of the types of aluminum alloy, aluminum alloy 6061 is a mixture of silicon and magnesium, a lighter metal. It has excellent ductility, strength, and corrosion resistance.
Alloys also conduct heat and electricity effectively and are also an alloying material to other materials like titanium and steel. They are machinable due to their hardness and castable due to the moderate melting point and flow ability in the molten state.
Grades of Aluminum and Aluminum Alloy
Common grades of aluminum alloys suitable for use as lightweight materials include:
- Aluminum 2024 is an aluminum-copper-manganese-magnesium alloy (Al-Cu-Mg) with high fatigue resistance and machinability. It is a wrought alloy applicable in the aerospace industry because of its strength and lightweight.
- Aluminum 6061 is an aluminum-silicon-magnesium alloy (Al-Si-Mg) with excellent corrosion resistance, formability, and weldability.
- Aluminum alloy 7075 is a high-strength aluminum-zinc alloy (Al-Zn) with good corrosion resistance and machinability.
- Aluminum alloy 5052 is an aluminum-magnesium alloy (Al-Mg) with excellent corrosion resistance and formability.
Advantages of Aluminum and Aluminum Alloy
- Excellent corrosion resistance by forming a protective oxide layer;
- Aluminum is approximately 1/3 the weight of steel, making it a perfect material for reducing overall weight;
- It is recyclable without losing its properties;
- Excellent conductivity and thermal properties;
- Aluminum alloys are formable and machinable.
Limitations of Aluminum and Aluminum Alloy
- Some aluminum alloys are expensive for example 2024 and 7075 aluminum alloys;
- Some aluminum alloys require heat treatment to achieve optimal properties therein.
Application of Aluminum and Aluminum Alloy
- Marine Industry: Boat hulls, ship superstructures, and propeller shafts;
- Automotive Industry: Car bodies, engine blocks, and wheels;
- Aerospace Industry: Aircraft fuselages, wings, and spacecraft components;
- Construction Industry: Window frames, roofing, and facades;
- Electronics Industry: Housings, heat sinks, and circuit boards;
- Consumer Goods Industry: Sports equipment, kitchen utensils, and furniture.
Titanium and Titanium Alloys
Titanium is a lightweight metal found in nature only as an oxide. It is a lustrous transition metal with a characteristic silver color, low density, high strength, and corrosion resistance. Titanium alloys contain a mixture of titanium and other chemical elements. As a result, they have improved tensile strength and toughness (even at extreme temperatures).
However, as seen in the titanium vs aluminum comparison, titanium alloy has low machinability because of its hardness. Furthermore, it has low thermal conductivity, which reduces heat dissipation, which is necessary in machining. As a result, specialized tools are required for effective and efficient manufacturing.
Grades of Titanium and Titanium Alloy
Common grades of titanium alloys suitable for various applications include:
- Titanium Grade 1 (CP4) is pure titanium with the highest ductility and softness. Furthermore, it has high corrosion resistance.
- Titanium Grade 2 (CP3) is another pure titanium with high strength and ductility.
- Titanium Grade 3 (CP2) is stronger than Grades 1 and 2. It also has moderate ductility and weldability.
- Titanium Grade 4 (CP1) is the strongest, but it has moderate ductility.
Advantages of Titanium and Titanium Alloy
- High strength-to-weight ratio;
- Excellent corrosion resistance;
- Titanium is recyclable;
- Its low modulus means it is less stiff (more flexible) than other metals.
Limitations of Titanium and Titanium Alloy
- Titanium has low machinability because of its hardness;
- Some titanium alloys have low ductility;
- Titanium alloys are expensive.
Application of Titanium and Titanium Alloy
Titanium alloys’ high strength-to-weight ratio and corrosion resistance make them widely applicable in industries requiring structural and high-performance parts.
- Marine Industry: Propeller shafts, heat exchangers, and subsea components;
- Automotive Industry: Engine components, exhaust systems, and suspension parts;
- Aerospace Industry: Structural components, landing gear, and jet engine parts
- Medical Industry: Implants, surgical instruments, and prosthetics;
- Sports Equipment Industry: Golf clubs, bicycle frames, and sports gear;
- Power Generation Industry: Turbine blades, heat exchangers, and condenser tubing.
Magnesium and Magnesium Alloy
Magnesium is a shiny gray metal with a low density, low melting point, and high chemical reactivity. It is considered the lightest metal, 33% lighter than aluminum and 75% lighter than steel.
Its alloys are mixtures of magnesium and other metals like aluminum, zinc, manganese, silicon, copper, etc., each giving it improved properties such as corrosion resistance, strength, ductility, and density.
Grades of Magnesium and Magnesium Alloy
Common magnesium alloy grades include:
- AZ31 is a magnesium-aluminum-zinc alloy with good strength, ductility, and excellent weldability;
- AZ61 is another magnesium-aluminum-zinc alloy with higher strength and good corrosion resistance;
- AZ80’s high strength and good machinability make it a choice when machining magnesium parts;
- AZ91 is a popular magnesium-aluminum-zinc alloy with balanced strength, corrosion resistance, and castability;
- ZE41 is a magnesium-zinc-rare earth alloy with high strength, good creep resistance, and excellent corrosion resistance.
Advantages of Magnesium and Magnesium Alloys
- Magnesium is one of the lightest structural materials with a high strength-to-weight ratio;
- Excellent dimensional stability;
- High Impact resistance;
- Its high castability makes it a common material in metal casting.
Limitations of Magnesium and Magnesium Alloy
- It is highly flammable;
- Magnesium and its alloys are susceptible to corrosion;
- It has a low melting point.
Application of Magnesium and Magnesium Alloy
- Automotive Industry: Engine blocks, transmission cases, and wheels;
- Aerospace Industry: Landing gear and interior parts;
- Industrial Uses: Power tools, machinery components, and structural frames;
- Commercial Applications: Electronics casings, sporting goods, and household appliances.
Beryllium and Beryllium Alloy
Beryllium is a silvery-white soft metal with a low density, high rigidity, high strength, structural stability, and reflectivity. It is distinguished among metals in terms of specific rigidity. Beryllium has the second lowest density compared to metals like magnesium, aluminum, and titanium, and high thermal conductivity, and corrosion resistance in ambient and elevated temperatures.
Grades of Beryllium and Beryllium Alloy
Beryllium and its alloys are classified into several grades, each with unique properties and applications.
- S-200 is a strong and stiff lightweight beryllium.
- S-65 has a good balance of strength, ductility, and machinability.
- I-220-H has excellent thermal conductivity and dimensional stability.
Advantages of Beryllium and Beryllium Alloy
- High dimensional stability, i.e., it is less prone to expand and shrink with temperature changes;
- It is transparent to X-rays, hence its use as medical imaging equipment;
- A superior thermal conductivity compared to alternative materials;
- It is a better electrical conductor than many other materials;
- Excellent corrosion resistance.
Limitations of Beryllium and Beryllium Alloy
- Beryllium is brittle which can limit its applications in environments that require flexibility;
- It is costly compared to other lightweight materials;
- Low machinability due to its brittleness and toxicity;
- Beryllium toxicity makes recycling difficult and costly.
Application of Beryllium and Beryllium Alloy
- Automotive Industry: Airbag sensors, brake rotors, engine components, and transmission housings;
- Aerospace Industry: Landing gear bearing, satellite structural components, and rocket nozzles;
- Medical Industry: X-ray windows for mammography, medical laser bores, surgical tools, and medical implants.
Table Comparison of Lightweight Metals
Metal | Density(g/cm³) | Strength-to-weight Ratio MPa/(g/cm³) | Corrosion Resistance | Cost |
Aluminum | 2.7 | 200-400 | Good | Medium |
Titanium | 4.5 | 500-600 | Excellent | High |
Magnesium | 1.7 | 200-300 | Fair | Low |
Beryllium | 1.8 | 300-400 | Excellent | Very High |
Copper | 8.9 | 100-200 | Good | High |
Steel | 7.9 | 100-200 | Good | Low |
How to Select the Suitable Lightweight Metal?
Selecting a lightweight metal depends on the project requirements which might necessitate considering the following factors.
Mechanical Properties
Consider mechanical properties such as metal strength, durability, ductility, machinability, and castability to choose the right material. Strong lightweight metals like aluminum and titanium can withstand the stresses and loads they will encounter.
Another mechanical property to consider is machinability, I.e., the ease of machining metals. For instance, aluminum has high machinability unlike titanium has low machinability due to its hardness and low thermal conductivity.
Thermal Properties
The thermal properties of metals impact their performance in environments with varying temperatures. For example, metals like aluminum alloys give excellent thermal conductivity, unlike titanium. Hence they are applicable in making heat exchangers and cooling systems.
Another thermal property is creep resistance, I.e., the ability to resist deformation under prolonged exposure to high temperatures. Titanium and certain high-strength aluminum alloys have good creep resistance.
Weight Consideration
Weight is a primary concern in many industries, especially in aerospace, automotive, and portable electronic devices. The metal must offer the necessary strength without adding excessive weight. Titanium and magnesium are common metals when considering weight.
Corrosion Resistance
Resistance to corrosion and other chemicals can affect light metal performance. Metals like titanium are popular because they perform well in harsh environments or those exposed to corrosive elements.
Cost
Cost is always a significant factor in material selection. While lightweight metals like titanium offer excellent performance, they are often more expensive than alternatives like aluminum or magnesium.
Manufacturing Technique Available
The available manufacturing technique can also determine the choice of material. For example, metal casting is suitable for alloys with good flowability such as 2024 aluminum and magnesium. Forgin gand stamping is suitable for making high-strength parts using materials like aluminum. Machining is suitable for materials with high machinability such as aluminum and magnesium.
Other Alternatives to Lightweight Metal
Aside from metals, there are other lightweight materials suitable for part manufacturing. Two common ones include:
Composite Materials
Composite materials are engineered by combining two or more constituent materials with different physical and chemical properties. When combined, these materials produce a composite that performs better than the individual components, often with enhanced strength, lightweight characteristics, or resistance to environmental factors.
Properties of Composite
- They exhibit superior strength compared to their individual components.
- Many composites are lighter than traditional materials like metal or wood.
- Composites offer better wear, impact, and corrosion resistance.
- They are customizable which makes them easy to tailor to specific.
Carbon Fiber
Carbon fiber, also known as graphite fiber, is a polymer renowned for its high strength and lightweight properties. It is composed of thin, strong crystalline filaments of carbon and is used to reinforce composite materials.
Properties of Carbon Fiber
- Carbon fiber is five times stronger than steel and twice as stiff, yet much lighter.
- It has high corrosion resistance.
- It can withstand high temperatures.
- Carbon fiber is moldable into various shapes and structures.
Conclusion
Lightweight metals like aluminum and titanium enable weight reduction, which makes them applicable in improving fuel efficiency, payload capacity, and overall performance. Although some are expensive, they are very important in several industries, such as automotive, aerospace, medical, and marine.
FAQs
Can titanium rust?
Pure titanium cannot rust or corrode on exposure to liquids like chemicals, acids, and saltwater.
In what way do lightweight materials affect part design?
Lightweight materials enable complex geometries, reduced material waste, and innovative solutions, allowing for increased design flexibility.
What is the cheapest and lightest metal in part manufacturing?
The cheapest lightweight metal is aluminum, and the lightest metal is magnesium.
Is titanium lighter than aluminum?
Aluminum is lighter than titanium (2⁄3 times heavier than aluminum). However, titanium is stronger and requires less material to achieve the same physical strength as aluminum.