Machining Titanium with YG-1 – 01. Materials

Information provided by
Global Industry Project Manager - Aerospace, Power Generation and Medical

Titanium is a pure element that, when combined with various metals or chemical materials, becomes the various titanium alloys that we can encounter in machine shops today. Titanium alloys have a very high tensile strength and toughness, even at extreme temperatures. Due to its light specific weight and extraordinary corrosion resistance, titanium alloys have become very popular in a wide number of applications and parts. However, the high cost for raw materials and processing often limits the use of titanium alloys to expensive military applications, commercial aircraft, spacecraft, and various energy components. Some familiar civilian products made with titanium alloys include high-performance bicycles, medical devices, jewelry, and other highly stressed components, including connecting rods for high-end sports cars, sports equipment, and electronics.

There are six types of titanium alloys: Pure titanium, Alpha alloy – (not heat treatable), Near Alpha alloy, Beta alloy, Near Beta alloy, and Alpha-Beta alloy. Among these alloys, the most popular for the aerospace industry is the Alpha-Beta alloy - specifically, type Ti-6AI-4V (also referred to as Ti 6-4 and Grade 5).

Just as Ti-6AI-4V is the most popular titanium alloy for aerospace, it is also the most commonly used alloy for all titanium applications. Ti-6Al-4V has a chemical composition of 6% aluminum, 4% vanadium, and 0.25% iron (max). The benefits of this grade include the fact that it is heat treatable. Ti-6AI-4V is also an excellent combination of strength, corrosion resistance, weldability and ease of fabrication.

Titanium components are machined in the forged condition or in solid blocks that often require removal of up to 90% of the weight of the workpiece. The high-chemical reactivity of titanium alloys causes the chip to weld to the tool and the low thermal conductivity of these materials do not allow the heat generated during machining, to dissipate from the tool edge to the part. This results in high temperatures at the cutting edge of the tool, which can lead to advanced tool wear. Additionally, excessive cutting speeds produce a chemical reaction between the chip and the cutting tool material, which can result in sudden chipping or breakage with inserts and round tools.

A significant challenge with machining titanium is, only 25% of the heat generated is released with the chip. This means the remaining heat generated during the machining cycle is transmitted to either the part or the cutting tool. Typically, the goal is to have no more than 10-15% of the generated heat transmitted to the workpiece, which means the cutting tool has to absorb as much as 60% to 65% of the heat generated. This is a primary reason for reduced tool life for cutting tools used for machining titanium alloys as compared to other materials such as steels and stainless steels.

A common solution to address heat when machining titanium alloys is the use of high-pressure coolant to mitigate heat as it is generated. An alternative method for heat mitigation is the use of cryogenics. While this method has been available for some time, cryogenics comes with a very high cost of entry. Updating the typical milling machine with cryogenics can cost as much as USD 60,000, so this is a process that shop owners do not arbitrarily adopt.

YG-1 has developed a range of cutting tools tailored for machining titanium alloys. For solid carbide high-performance end mills, YG-1 offers a choice between V7 Plus 4 flute & TitaNox Power, TitaNox Power 5 flute, V7 Plus 6 Flute and 7 flute special end mills designed explicitly for milling titanium alloys. These solid milling options include a combination of unique geometries, coatings, and edge prep for machining titanium alloys. These end mills are designed to perform with conventional or high-speed machining techniques and can operate between 160-500 SFM (55-160 m/min) and 20 -120 IPM (500-3000 mm/min) depending on the application and depth of cut. YG-1’s latest product for milling titanium alloys is the universal TitaNox Power HPC 5 Flute design.

< TitaNox-Power HPC >

YG-1 also offers 4, 5, 6, 8, and 10 flute Tank-Power HSS-PM end mills and Sine-Power cobalt end mills designed for milling titanium alloys. Additionally, YG-1 offers a robust special program for designing and manufacturing custom-made special end mills for any material, including titanium alloys. YG-1 developed the Dream Drills Titanium for hole making with unique geometry, carbide grade, and PVD coating specifically for drilling titanium alloys.

< Dream Drills Titanium >

For threading applications, YG-1 offers YG Tap TiNi – a complete line of HSS-PM taps designed for tapping through and blind holes in titanium and nickel alloys.

< YG Tap TiNi >

The YG-1 Aerospace Team, including Dr. Abdelatif Atarsia (Industry project Manager - Aerospace & Composite Assembly), Mr. Matthieu Guillon (Key Account Manager EMEA - Aerospace), Mr. Kevin McCall (Industry Project Manager North America - Aerospace, Power Generation and Medical) and Mr. Yair Bruhis (Industry project manager of Aerospace, Power generation and Medical), is ready to support you with all aerospace opportunities and titanium alloy applications for any industry.