Titanium Alloys

The Complete Guide to CNC Machining Titanium alloys

Titanium alloys are a group of high-performance metals composed primarily of titanium, often alloyed with elements such as aluminum, vanadium, molybdenum, and iron. Titanium alloys are celebrated for their high strength-to-weight ratio, corrosion resistance, and biocompatibility, making them ideal for use in aerospace, medical, automotive, and industrial applications. Titanium is roughly 60% denser than aluminum but has twice the strength, which gives it a unique advantage in applications where both strength and low weight are critical factors.

The inherent corrosion resistance of titanium alloys is due to a stable, protective oxide layer that forms on the surface, making these alloys resistant to many chemicals, including chlorides, acids, and seawater. This corrosion resistance is especially beneficial in industries such as marine, medical, and chemical processing. Additionally, titanium alloys maintain their strength at high temperatures, allowing them to perform well in environments where other metals, like aluminum or stainless steel, might weaken. 

In the context of CNC machining, titanium alloys present specific challenges due to their hardness and tendency to work-harden, which can accelerate tool wear. Titanium is also a poor conductor of heat, causing it to retain heat near the cutting area, which can lead to thermal damage to both the material and cutting tool if not managed correctly. As a result, machining titanium alloys requires careful planning, specific tool materials, and optimized machining parameters to achieve accurate and efficient results.

Subtypes

Alpha Alloys

These alloys contain alpha stabilizers, such as aluminum and oxygen, and have a hexagonal close-packed (HCP) crystal structure. Alpha alloys are known for their excellent corrosion resistance and stability at elevated temperatures, although they have lower strength than beta or alpha-beta alloys. They are non-heat-treatable, making them suitable for applications that demand high-temperature stability, such as jet engine components, chemical processing equipment, and marine environments.

Beta Alloys

Beta alloys include elements like vanadium, molybdenum, and niobium, which stabilize the beta phase and provide a body-centered cubic (BCC) crystal structure. Beta alloys are highly formable and can be heat-treated for higher strength. They are generally used in applications that require a combination of strength, formability, and toughness, such as aircraft structures and biomedical implants. However, they are more susceptible to corrosion than alpha alloys.

Alpha-Beta Alloys

These alloys contain a mix of alpha and beta stabilizers, making them the most versatile type of titanium alloy. The most widely used alloy in this category is Ti-6Al-4V (Grade 5), which has a balanced combination of strength, corrosion resistance, and workability. Alpha-beta alloys are heat-treatable, providing a range of mechanical properties that can be customized for specific applications, from aerospace components to sports equipment and medical devices.

Each subtype of titanium alloy offers specific benefits tailored to different industrial needs, enabling them to be applied in demanding environments where traditional materials might fail.

Surface Finishes

Anodizing

This electrochemical process forms a thicker oxide layer on titanium surfaces, enhancing corrosion resistance and allowing for decorative coloring. Anodizing is commonly used in medical and consumer products to improve durability and aesthetics.

Shot Peening

This process involves bombarding the titanium surface with small spherical particles to introduce compressive stress, which increases fatigue resistance. Shot peening is widely used in aerospace components to improve durability under cyclic loading.

Chemical Milling

Chemical milling is a controlled etching process that removes material from the titanium surface to reduce weight and achieve specific thicknesses. It is commonly used in aerospace applications to optimize the weight of structural components.

Electropolishing

Electropolishing smooths and brightens the titanium surface by removing a thin layer of material. It enhances corrosion resistance and is particularly useful for medical implants and other applications requiring a biocompatible surface.

Design Tips

Use of Carbide or Cobalt Tools

High-quality carbide or cobalt tools are essential for machining titanium due to its hardness and tendency to work-harden.

Optimized Feed Rates

Maintain a moderate feed rate to minimize tool wear and avoid excessive heat generation.

Controlled Depth of Cut

Limit the depth of cut to reduce stress on the cutting tool and prevent thermal damage.

Coolant Application

Apply ample coolant to reduce heat and prevent overheating, which can damage both the material and tool.

Stable Fixturing

Titanium’s lightweight nature requires stable fixturing to prevent movement and ensure dimensional accuracy during machining.

Reduced Cutting Speeds

Use lower cutting speeds to prolong tool life and reduce heat buildup, especially for alloys like Ti-6Al-4V.

Chip Control

Titanium forms long, continuous chips, so chip-breaking strategies or chip removal systems are essential to prevent re-cutting and tool damage.

Post-Machining Finishing

Titanium often requires surface treatments such as deburring, polishing, or anodizing after machining to meet final specifications and improve appearance or corrosion resistance.

FAQ

What are titanium alloys primarily composed of?

Titanium alloys are primarily composed of titanium with other elements like aluminum, vanadium, and molybdenum to enhance strength and other properties.

Why are titanium alloys used in aerospace?

Titanium alloys offer high strength-to-weight ratios and excellent corrosion resistance, making them ideal for aerospace applications requiring lightweight yet strong materials.

What are the main types of titanium alloys?

The main types are alpha alloys, beta alloys, and alpha-beta alloys, each with unique properties suitable for different applications.

What is Ti-6Al-4V?

Ti-6Al-4V (Grade 5) is an alpha-beta alloy known for its excellent balance of strength, corrosion resistance, and workability, widely used in aerospace and medical applications.

Can titanium alloys be anodized?

Yes, anodizing enhances corrosion resistance and adds aesthetic colors to titanium surfaces.

What tools are best for machining titanium alloys?

Carbide or cobalt tools are recommended due to titanium’s hardness and tendency to work-harden.

How is heat managed during CNC machining of titanium alloys?

Ample coolant is applied to prevent overheating, and lower cutting speeds help minimize heat generation.

Are titanium alloys corrosion-resistant?

Yes, they are naturally corrosion-resistant due to a protective oxide layer that forms on the surface.

Which titanium alloys are suitable for high-temperature applications?

Alpha alloys are preferred for high-temperature applications due to their stability at elevated temperatures.

What is shot peening used for in titanium alloys?

Shot peening introduces compressive stress to enhance fatigue resistance, commonly used in aerospace components.

Article about Material

Our Capabilites

CNC Machining Services

Precision CNC machining services including CNC turning, milling, drilling and more.

Injection Molding Services

Discover endless options of our custom injection molding service. No MOQ and tight tolerance.

Sheet Metal Fabrication

Check out our online sheet metal cutting and bending service. Upload your file and get a free quote today.

Custom 3D Printing Services

Get a rapid prototyping or final printed parts with our online 3D printing service.

GET FREE QUOTE

You’re one step from the  factory-direct price of part manufacturing services.