Aluminum vs Titanium: The Engineer’s Guide

When an engineer thinks about lightweight metals, they often come up with two options: titanium and aluminum. Though these two materials are often lumped together, they’re very different. Our machinists at Rapid Axis have experience working with both, and this engineer’s guide will teach you which material is right for your next project. 

What Is Aluminum?

Aluminum is a low-cost, lightweight metal that has incredible machinability, weldability, and good corrosion resistance. Pure aluminum is really soft, but alloyed aluminum is stronger and more durable. 

With a density roughly 60% lower than titanium, aluminum is the much lighter option. If your project demands a lightweight material but doesn’t require excessive strength, then aluminum might be the no-brainer option.

Aluminum also has great thermal and electrical conductivity, and it’s used in heat sinks and electronic housings. Since aluminum is non-ferrous, you won’t have to worry about its interaction with electronic or magnetic fields.

Aluminum is one of the less expensive metals that can be CNC machined, bent, welded, and assembled.

Common Aluminum Alloys in Machining

Aluminum can be found in a lot of different alloys, which are combinations of aluminum with other elements. With dozens of alloys to pick from, you can fine-tune the mechanical properties that you’re looking for.

Although you can find aluminum alloys ranging from 1000 to 7000 series, the 6000 series is definitely the most common. This series adds magnesium and silicon to the aluminum base, creating a strong, versatile, corrosion-resistant, easily machinable, durable alloy.

6061 aluminum is an incredibly common alloy that combines these favorable mechanical properties with the ability to easily machine, weld, bend, and manufacture the parts.

Pros of Aluminum

Aluminum is a great material choice for a lot of different industries. You can find aluminum blocks, bars, sheets, plates, and structural shapes to start with, potentially minimizing the machining required. In addition, stock aluminum pieces are very affordable, and machining is quick and easy. This results in lower manufacturing quotes and more money in your pocket.

We can use aluminum in rapid manufacturing cycles, since it deals with heat well and dissipates it quickly. Often, this translates to lower turnaround times and quicker manufacturing. 

6061 aluminum can be anodized, powder coated, painted, and more. These finishing steps can refine how your parts look, ensuring a uniform finish that matches your branding or required aesthetics. 

Since aluminum is so readily available, we might have the correct stock piece in our inventory, so we can start working on your projects sooner.

Cons of Aluminum

The biggest limiting factor for aluminum is its ultimate strength, the total amount of force that can be supported before the part catastrophically fails. 6061 aluminum has an ultimate tensile strength of 310 MPa, and Grade 5 titanium’s is 1,100 MPa, so aluminum offers about 1/3 the total strength of titanium. This can be a decision-making factor for many projects that require parts to support heavy loads.

Another thing to consider is that aluminum starts to fail sooner in a high-temperature environment. While aluminum has decent thermal properties, they pale when compared to titanium’s.

Another drawback of aluminum is that it’s a softer metal, so surface imperfections happen quicker. Aluminum is more susceptible to surface wear, scratches, dents, and dings. You’ll have to worry about aesthetic imperfections as well as failure due to high-friction applications. Anodizing can help with some added durability.

What Is Titanium?

Titanium is a high-strength, lightweight metal that is incredibly corrosion-resistant and very strong. It is significantly more expensive than aluminum, but it also offers mechanical properties that are significantly better.

With a lower density and much higher strength, titanium has one of the best strength-to-weight ratios for any stock metal.

You’ll find titanium used across industries, especially where engineers want to minimize overall weight without sacrificing the strength of the part.

Common Titanium Alloys in Machining

Although you can find a few different grades of titanium on the market, the two most common options are Grade 2 and Grade 5.

• Grade 2 Titanium is easier to machine and has better corrosion resistance. This is the better option for applications in high-moisture environments.
• Grade 5 Titanium is the more popular titanium alloy. It has a higher strength and low weight, making it a good choice for aerospace and defense projects. Typically, this is the alloy of titanium that people think about using for projects, unless there are specialized requirements. 
• Grade 7 Titanium is reserved for applications that involve regular exposure to moisture or chemicals. It is a commercially pure alloy that includes palladium for incredible corrosion and chemical resistance. However, Grade 7 is weaker than Grade 5, so it shouldn’t be used for structural parts.

Pros of Titanium

The major benefit of titanium is its strength-to-weight ratio. Titanium can handle a lot of weight without weighing a lot, so you can create structural parts that weigh a fraction of what a steel or aluminum part would weigh. This reduction of mass is a game-changer for projects that have strict mass requirements or need to optimize the performance of a vehicle or assembly. 

In addition, titanium is naturally corrosion resistant. Titanium parts are known for long-term durability, making maintenance and swapping parts more infrequent throughout the lifetime of your parts. 

With its impressive strength, Grade 5 titanium parts have great fatigue resistance and resistance to failure due to cyclical loading.

Cons of Titanium

A major drawback of titanium is that it is significantly more expensive than aluminum. Not only is the raw material more expensive, but it can be harder to source in different sizes, and the machining is more difficult, so we have to charge more for machining titanium parts as compared to aluminum parts.

The big difference is the low thermal conductivity of titanium: since the heat doesn’t dissipate nicely, the machines’ tooling wears more quickly, and the machinists need to use slower machining speeds to create high-quality parts. The benefit of choosing Rapid Axis instead of a shop that isn’t familiar with titanium is that we already know the perfect machine settings and how titanium reacts. Using an inexperienced shop can lead to even bigger and more expensive issues during machining. 

Aluminum vs Titanium: Key Differences

Although titanium and aluminum are relatively similar on paper, titanium pulls ahead in almost every category. Of course, there’s a big price difference that goes along with these improved mechanical properties. 

Titanium is a lot stronger than aluminum, and it can be cyclically loaded longer before failing, making titanium the better option in structural parts.

Aluminum is more readily available, comes in more stock shapes, and is much easier to machine and more affordable. For larger projects, the machining turnaround time and cost differences will really stand out between aluminum and titanium. 

Applications of Aluminum vs Titanium in Key Industries

In the aerospace industry, both materials are incredibly common. Aluminum is a great general use metal that doesn’t weigh much and is inexpensive to purchase and machine. You can find it used in interior components and even structural panels. Titanium is used in larger parts or areas where weight consideration has a big impact on the functionality of the aircraft. 

Medical devices tend to use aluminum for equipment housings and various components. Titanium is used for implants due to its biocompatibility, corrosion resistance, and durability. If you know someone who recently had a knee, shoulder, or hip replacement, there’s a very good chance their new joint is titanium. 

Automotive companies tend to stick with aluminum (or steel) for consumer vehicles. Battery enclosures, framework, body panels, and suspension components rely heavily on aluminum since they can be machined easily and are affordable. Titanium is reserved for high-performance vehicles to reduce weight and optimize the mechanical performance of the cars.

Which Metal Should You Choose?

It might seem that titanium and aluminum are like-for-like replacements of one another. They are both lightweight metals that can handle weight, and both options are used across industries for similar parts. However, the two metals can’t be compared that way.

Titanium is the more expensive, more durable, stronger older brother to aluminum. In our experience, titanium should only be reserved for projects that need the added mechanical benefits of titanium; whether that’s the increased ultimate strength, better corrosion resistance, or biocompatibility that titanium offers.

In all other cases, aluminum or steel should be used. Aluminum is a fantastic general use metal that you can use for parts that don’t have specific strength requirements. For many engineers, aluminum is the default metal unless the project demands something that aluminum can’t handle.

By structuring your projects this way, you’ll save a ton of time and money in the machine shop. It’s no exaggeration that an aluminum part can be 30 times less expensive than a titanium part, and that rift only gets bigger as you look at larger and more complicated parts.

Conclusion

The good news? Our team at Rapid Axis has extensive experience with both aluminum and titanium. With common alloys in our warehouse, we can get started on your project quicker and offer realistic timelines for every part. We’ve fabricated countless aluminum and titanium parts during our decades in business, and we are confident that we can help with your upcoming project.

In addition, we offer a number of finishing operations that can maximize the functionality of your parts. From anodizing to powder coating and polishing, you can get the most out of your parts when you choose Rapid Axis.

Reach out to our expert machinists today to see which material is right for your next project. Get a free quote and get started with Rapid Axis.