Titanium is a robust material, boasting great mechanical strength combined with remarkable lightness, is highly resistant to corrosion, and can withstand extreme temperatures. In addition to all this, titanium is a nontoxic and biocompatible material, meaning it has no harmful effect on the organisms with which it comes into contact.

Because of these peculiar properties, titanium, or its alloys, are used for a vast range of purposes, in a great many productive sectors: from everyday objects and tools to components for the most sophisticated equipment used by man. They range, thus, from aerospace to shipbuilding, from chemical instrumentation to prosthetics in the medical field.

Origin, properties and mechanical properties of titanium

The main ore from which titanium is extracted is ilmenite, whose deposits are found in Ukraine and Norway, as far as the European continent is concerned, and in Canada and Australia, for the rest of the globe.

Titanium can also be made from a second mineral, rutile, which is abundant in North America and South African soil.

Why choose titanium: physical and mechanical characteristics

Titanium is a material with prodigious mechanical properties. Non-magnetic, it boasts excellent tensile strength, equal to that of the most common steel alloys, and a significantly higher density than that of the most common aluminum alloys.

Characteristics, these, that make titanium particularly suitable for the production of mechanical parts, such as frames and small parts, for example.

But these are not the only physical characteristics that make titanium the best possible choice as a material in multiple applications.

Physical and technical characteristics of titanium

Corrosion resistance

After platinum, titanium is the metallic material with the best corrosion resistance. In contact with oxygen in the air and water, by an electrochemical phenomenon-passivation-titanium develops a dense oxide layer on its surface that exerts a protective function from external agents.

Because of this phenomenon, titanium is used in the marine industry, for the production of parts in contact with seawater, such as engine propellers.

The oxide layer that lines the surface of titanium is also responsible for the material’s characteristic color change.

Resistance to thermal stresses

Titanium is a material with good heat transfer properties; it has a coefficient of thermal expansion only slightly lower than steel and about half that of aluminum.

One of the most important properties of titanium, is its melting point of 1725 °C, about 400 °C higher than that of steel and about 1000 °C higher than that of aluminum, a factor that makes it a suitable material For all those applications where you reach extremely high temperatures, as is the case with the aerospace sector.

Low specific volume

Another physical property of titanium, which makes it a perfect material for many applications, is its low specific volume: an object made of titanium weighs roughly half as much as the same one made of steel.

Titanium: processing difficulties

While the special properties of titanium mean that finished products offer significant and numerous advantages, they can also be a hindrance during processing. In particular, making titanium turning and milling difficult are:

Reduced thermal conductivity

The heat developed by friction during machining is not dissipated fast enough; it concentrates in the cutting area and in the tool itself, damaging it.

High chemical reactivity

It causes welding between the chip and the tool used for its removal, causing abrasion on the material and rapid wear of the tool itself.

Low modulus of elasticity

It causes the material in the cutting zone to deflect away from the tool, causing it to vibrate. This phenomenon reduces cutting efficiency, adversely affecting machining quality and accelerating tool wear.

From this it follows that, for the mechanical processing of titanium, special attention should be paid to several factors:

• the specifications of the machine
• the specifications of tools and tool holders
• The pressure and volume of cutting fluid for chip removal.

It is, moreover, essential to carefully follow clear guidelines for machine programming and machining execution.

Similarly, it is essential to perform thorough preliminary checks on the quality and composition of the raw material, as well as rigorous checks on the finished piece.

What Lomec Aerospace can do

Nowadays, the market demands high-quality titanium products, often with very low iron and hydrogen values. Therefore, upon request, Lomec performs specific chemical analysis on the composition of the material to be processed and ascertains its correct composition.

In parallel, the material can be subjected to mechanical tensile and resilience tests.

Internally, “Non-destructive tests,” i.e., ultrasound (level II) and color-contrast liquid penetrant (level II), are, then, performed in accordance with the international European UNI EN ISO 9712 and American ASNT-TC-1A standards.

List of possible machining operations

Here are the processing steps that Lomec can perform on titanium:

• Roughing: consists of removing from the raw material the natural “protective” crust formed by oxidation on the outer surface of titanium, especially in the case of forging processes. This process is done through the use of particularly robust lathes and milling machines and tungsten carbide tools.
• Finishing to drawing: performed by means of precision lathes and CNC machining centers with certified processes.
• Control: guaranteeing the quality of titanium processing is not enough, in Lomec a scrupulous control of material characteristics is performed for each of the different stages of the production cycle, from the procurement of raw material, to the delivery of the finished product. This step is critical to ensure that the most reliable titanium material and machined products are brought to market.
• Testing, checking and testing: not only checks on the quality and physical structure of the material, rigorous checks are carried out in Lomec to verify the goodness of processing. This is a crucial step, especially in all those critical situations where even one slight imperfection could jeopardize the proper functioning of large facilities and endanger the structure within which they are located as well as the safety of workers.

In order to achieve a quality product, one must rely on a reliable partner with a proven track record in titanium processing, as well as an appropriate machine fleet and processes.

Lomec supports you not only by performing state-of-the-art titanium machining, but also stands by you, putting all the accumulated know-how at your disposal, offering consulting and co-engineering services.