Mastering Difficult-to-Cut Materials in Aerospace

Difficult-to-cut materials are defined as engineering materials with significantly lower machinability compared to typical ones.

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These materials are often referred to as “hard-to-machine,” “tough-to-cut,” or even “nasty” in shoptalk. It is important to note that high hardness is not the only characteristic that makes these materials challenging to machines, as several other factors contribute to their machining difficulties.

In fact, every industrial branch, in one way or another, must deal with such materials. However, the main consumer of these materials is the aerospace industry. It is in this sector, whether in the production of turbine engines, landing gear components, or primary airframe elements, that difficult-to-cut materials have found their greatest application. In the aerospace industry, the key characteristics of required materials are strength-to-weight ratio, robustness, fatigue life, and resistance to corrosion and hot temperatures. It turns out that materials meeting these characteristics are difficult to machine, posing a serious challenge for production. When speaking about such materials, the following information should be considered.

• High-alloy high-strength steel,

• Titanium alloys,

• Hot temperature superalloys,

• Composites.

High-strength steels are used in elements subjected to extreme mechanical load, such as landing gear. Additionally, this is the primary material for various fasteners.

Titanium alloys, with their excellent strength-to-density ratio, high corrosion resistance, and creep resistance, have become the preferred material for producing the main parts of the cold section of a jet engine. These alloys also provide a suitable alternative to steels and stainless steels for weight saving.

Hot Temperature Superalloys (HTSA), which can maintain their strength in high-temperature environments, are common in the components of the hot section of a jet engine.