In the CNC machining industry, titanium and aluminum are both quite common metal materials. Both materials are lightweight and corrosion-resistant, and can be made into many types of parts, which are widely used in various industries. Their versatility has also made them popular in many manufacturing industries, such as 3D printing, casting, etc. But because of this, many manufacturers and engineers have doubts about the choice of the two, and do not know which material is more suitable for their plans. This article compares various aspects of titanium and aluminum to provide you with decision-making ideas.
What is Titanium?
Titanium (Ti) is a silver-white transition metal with an excellent strength-to-weight ratio. It is about 45% lighter than steel, but has the same strength as steel. The melting point of titanium is also extremely high, at around 1688°C. In addition, the material is non-toxic, non-magnetic and has excellent biocompatibility, so it can be used in medical implants.
What is Aluminum?
As the most common metal in manufacturing, aluminum (Al) is often considered the “friendliest” metal. It is a silvery-white light metal. It has excellent ductility and thermal conductivity, so it can be used as an excellent raw material for many types of parts. However, pure aluminum is too soft and sticky for CNC machining. Therefore, aluminum alloys are generally commonly used. The most common aluminum alloys include the 6xxx series (such as 6061-T6), the 7xxx series (such as 7075-T6), and the 2xxx series (such as 2024).
Material Properties of Aluminum and Titanium
Below is a specific specification data table, which allows you to see the specific data comparison more intuitively.
| Property | Unit | Aluminum (6061-T6) | Titanium (Ti-6Al-4V) |
| Density | g/cm3g | 2.70 | 4.43 |
| Hardness | Brinell (HB) | 95 | 334 |
| Tensile Strength | MPa | 310 | 950 |
| Modulus of Elasticity | GPa | 68.9 | 113.8 |
| Thermal Conductivity | W/m⋅K | 167 | 6.7 |
| Melting Point | ℃ | 582 – 652 | 1604 – 1660 |
Comparison: Aluminum vs. Titanium
Next, we will compare the two materials in detail from multiple angles and analyze the differences between the two in a certain aspect.
Titanium vs Aluminum Weight
First of all, there is the weight issue that you are concerned about. This can be said to be a typical characteristic of titanium and aluminum. And which one is lighter, Titanium or Aluminum? Here I can tell you the answer directly – aluminum is lighter. Because at the same volume, titanium weighs about 1.6 times as much as aluminum. The density of aluminum is 2.7 g/cm3, and the density of titanium is 4.5 g/cm3.
If you need a part that is as light as possible, aluminum is a good choice. As for why aircraft landing gear or engine blades are made of titanium, we have to mention another important feature of them, which we will talk about below.
Impact of Density on Weight Ratio
Density can be said to be an important factor in determining weight. To calculate the weight ratio, we need to know the most basic physical equations first:
m (Weight) = ρ (Density) × V (Volume)
According to the above formula, as long as aluminum and titanium are produced into two parts with absolutely equal shape and volume. Then the ratio of their weights is equal to the ratio of their densities. We already know the density of the two materials, so we can directly calculate the weight ratio:
2.7 / 4.5 ≈1.67
That is to say, as long as the volume of the object is fixed, the weight of the titanium product is always 1.67 times that of the aluminum product.
Titanium vs Aluminum Strength
In fact, parts in many industries require not only lightweight properties but also exceptional strength. Aerospace components are a typical example. Comparing the strength of titanium metal to aluminum metal, titanium wins by far. The tensile strength of titanium alloy can reach an extremely high 950 MPa. While the highest tensile strength of the highest grade aluminum alloy can only reach 572 MPa.These figures clearly show you the strength difference between them.
Furthermore, titanium metal also has another “killer” strength property – fatigue strength. Fatigue strength refers to whether a metal will crack under repeated stress (such as vibration, bending). Aluminum materials have no fatigue limit, so aluminum parts may break after being used in extreme pressure environments for a long time. However, titanium material has a definite fatigue limit. Therefore, as long as the stress on titanium parts remains below a certain threshold, these parts can withstand cyclic loading indefinitely without breaking.
At the same time, there is a big difference between the two materials in terms of hardness and wear resistance. Aluminum is relatively soft, even if it is an aluminum alloy, it is relatively easy to scratch. On the other hand, titanium’s performance is much better. It is difficult to be scratched and has better wear resistance.
Titanium vs Aluminum Price and Cost
Price is also an issue that many manufacturers will consider when formulating project plans. Typically, titanium is 10 to 20 times more expensive than aluminum. If your parts also involve complex processing techniques, then the price gap will widen.
As of the writing of this article, the price of aluminum is about US$2-2.5 per kilogram, and the price of titanium is about US$12 per kilogram. By the way, if you want to know more about the price of titanium metal, you can check out another article on the website: “Cost of Titanium Per Pound“.
There’s another factor I want to talk about here which is scrap recycling. Scrap recycling is also plays a huge role in material costs. Aluminum scraps can be easily recycled and melted down, so their cost recovery rate is high. Titanium is easily contaminated at high temperatures, and it is very difficult and expensive to recycle titanium chips and re-refine them into high-quality titanium.
Factors to Consider When Evaluating Cost-Effectiveness
When considering the cost-effectiveness of a project, you can start with these factors. The first is the initial acquisition cost, and you cannot ignore the difficulty of material machining. The second point is operational savings. Whether the properties of the material meet your usage needs. Whether the parts made of these two materials can play their due role. The third point, which is maintenance cost, is a key factor for you to consider. For example, although aluminum materials are relatively cheap, they require maintenance in extreme environments, which is also a cost. Although titanium metal costs a lot upfront, it requires almost no maintenance or replacement.
Titanium vs Aluminum Machinability
When it comes to machinability, titanium and aluminum materials can be said to be at two extremes. Aluminum is easy to process, has good ductility, fast cutting speed, and low tool loss, so aluminum has become one of the most commonly used materials. It can be made into parts of various shapes through CNC milling, CNC turning and other processes.
Titanium is different. It has high hardness and poor thermal conductivity. The heat generated during cutting does not dissipate, but rather builds up completely on the cutting edge and workpiece surface. This leads to quick overheating, softening, or burning of the cutting tool. Therefore, when machining titanium part,s you must flood it with high pressure coolant. Another thing to keep in mind is that titanium is prone to galling at high temperatures.
Titanium vs Aluminum Thermal Conductivity
The thermal conductivity difference between aluminum and titanium is enormous. The thermal conductivity of aluminum is very high, second only to copper and silver, about 205 – 237 W/(m·K). Aluminum can rapidly absorb heat and dissipate it into the surrounding air, making it an ideal machining material. And the tool is not prone to overheating when custom aluminum machining. However, for this reason, various titanium parts are often used at high temperatures to prevent heat transfer.
Titanium vs Aluminum Corrosion Resistance
Titanium is undoubtedly one of the best metals when it comes to corrosion resistance. Titanium forms a dense oxide film (titanium dioxide) on its surface, which is stable and has excellent self-healing properties. So titanium typically does not need any kind of anti-corrosion coating. Aluminum also forms an aluminum oxide film on its surface, which allows the metal to gain stronger corrosion resistance. But you should be careful not to use aluminum parts in chlorine-containing environments (such as seawater). This is because chloride ions will penetrate the oxide film and cause corrosion inside the aluminum parts. At the same time, aluminum parts still need to undergo anodizing or painting surface treatment processes to improve their anti-corrosion capabilities
Titanium vs Aluminum Applications
Titanium and aluminum are very clearly divided in actual application areas. Aluminum occupies 90% of daily and factory areas, while titanium is used in the other 10% of high-end and extreme scenes.
First, let’s talk about the application fields of titanium. Titanium parts are expensive to machine, but their high strength and low thermal expansion are the reasons why these parts are popular. Therefore, titanium metal is often used in aerospace (such as jet engine blades, landing gear), medical (such as artificial joints, dental implants), sports equipment (such as customized bicycle frames) and other industries.
The application range of aluminum is obviously much wider than that of titanium. Its excellent properties such as lightness and corrosion resistance allow the metal to be used in many industries, such as aerospace, automobiles, construction, daily necessities, etc. 7075 can be made into aircraft wings and internal frames because of its high strength, 6063 can be made into radiators because of its thermal conductivity, and 6068/6061 can be made into car chassis suspension arms because of its forging performance.
Titanium vs Aluminum Post-Processing
You also know that in the machining industry, the post-processing of parts is a very important link, which determines the properties and appearance of the parts. The post-processing methods of titanium and aluminum metal parts are also different.
Anodizing
Aluminum will form a dense aluminum oxide film on its surface through an electrochemical reaction. This film not only improves the hardness of the aluminum parts but also allows the aluminum to be dyed any color you want due to its microporosity. The cost to you is also very cheap.
As for the anodizing process of titanium, you can control the thickness of the titanium oxide film by adjusting the voltage.Different thicknesses will refract different wavelengths of light.
Polishing
Aluminum is a soft material, so aluminum parts can be easily polished to a brilliant mirror finish, but they are also prone to scratches. Due to its tendency to stick to the knife, titanium can easily form an orange peel texture on its surface during polishing. The entire polishing process requires a lot of patience on your part.
Coating
Electroless nickel is the most commonly used functional coating on aluminum, providing extremely high hardness and corrosion resistance to aluminum parts. PVD is the best coating solution for titanium metal. For example, you can coat titanium with a black DLC. Such titanium parts have extremely high hardness and an extremely low friction coefficient.
Welding
Welding is a relatively difficult post-processing method for aluminum parts. Because aluminum has high thermal conductivity, aluminum parts are easily welded through and can easily produce pores. The welding process of titanium is more complicated. When welding, not only the welding gun must be sprayed with argon gas, but the back side must also be filled with argon gas for protection. You even need to perform welding operations in a vacuum box. This is because titanium absorbs oxygen, nitrogen and hydrogen at high temperatures, causing the weld to become brittle. And I must remind you that the color of the weld must be silver-white. If it is blue or purple, it means the welding failed and the part is scrapped.
Titanium vs Aluminum DFM
DFM is something that many engineers must consider when drawing. You definitely want the parts you design to be easy to use, easy to make, and affordable.
Geometry
In CNC machining, geometric structural parts are common. If you want to use aluminum to make structural parts, then you should consider the stiffness of the aluminum parts. To ensure their strength, you often need to increase the wall thickness of the aluminum part or add stiffeners when designing. If you want to use titanium to make structural parts, then you should avoid making thin-walled deep cavities, because titanium is highly elastic, so the thin titanium wall will vibrate violently, which will cause the surface of the part to deform.
Threads & Assembly
This is a problem-prone part of DFM. Aluminum parts need to pay attention to anti-slip, especially in screw holes that need to be disassembled frequently, you need to use Helicoil or Key-sert to enhance thread strength when designing. Titanium has serious cold welding problems, so you must specify in the drawings the use of anti-seize agents or special coatings on the threads.
Tolerances
Tolerance is also something engineers will pay attention to when designing. Aluminum has stable dimensions, so you can confidently specify tight tolerances on drawings. The factory is also easy to process into corresponding parts, and the cost does not rise. For titanium, you should pay attention because titanium will rebound after being machined under force, and the heat accumulated by processing will also cause the part to expand. In order to solve these problems, my suggestion is that unless there are special requirements, you should not mark too high accuracy requirements on the titanium part drawings. The second is that you need to consider the margin, and the design should take into account the stress release during processing.
Material Utilization
This is the core of cost control. Aluminum itself is cheap, so reasonable material waste caused by the subtractive manufacturing process is acceptable. Since titanium itself is expensive and difficult to process, you should consider casting, forging or 3D printing processes when designing parts.
Conclusion
The above is all the comparison content. I hope it can give you a deeper understanding of the two materials. Of course, our dsr is an experienced CNC machining manufacturer. If you have custom CNC aluminum parts or custom titanium machining service needs, you can contact us, I believe we can provide you with high-quality parts.
FAQ
Q1: What are the disadvantages of titanium?
A: First, titanium has a very high overall cost. Second, titanium is difficult to process, resulting in low processing efficiency.
Q2: Does titanium last longer than aluminum?
A: Yes. In most harsh environments, titanium has a service life far longer than aluminum.
Q3: What is the top 5 strongest metal?
A: Tungsten, Titanium, Chromium, Inconel, steel.
Q4: Is diamond or titanium stronger?
A: In terms of hardness, diamond is greater than titanium. But in terms of toughness and tensile strength, titanium is greater than diamond.
Q5: What is the enemy of titanium?
A: Reactive gases at high temperatures and hydrofluoric acid.
Q6: What are the disadvantages of aluminum?
A: No fatigue limit and poor heat resistance.
