Picking the Right Tools for Machining Titanium
Understanding which tools to use is an important part of any business that machines titanium. If you buy tooling made from the wrong material it
could wear too quickly, which means more wasted changover time and a higher overall tool cost. The challenge is to find the right tooling for the right price. To do this, you must first understand the materials most commonly used in tool making. The majority of tooling breaks down into four categories, which are high-speed steels (HSS), cast alloys, carbides and ceramics.
HSS got its name because it was designed to cut at very high speeds. It is the most highly alloyed tool steel and usually contains tungsten, chromium and vanadium, but this can vary by supplier. High-speed steel tools can be used to machine titanium but they wear quickly and any shop working with high throughput will lose money on the changover costs.
Cast cobalt alloys combine cobalt, chromium and tungsten to provide a tool with good wear resistance. Unfortunately, they have lacklustre hardness at around 60 Rc. This is simply not hard enough for machining titanium but it can still be used for some softer metals.
This is the most common material used when machining titanium. It is incredibly hard over a wide range of temperatures, has high thermal conductivity and has a high modulus of elasticity. Carbide tooling can usually be broken down into two groups. These are tungsten carbide and titanium carbide. Carbide tools come in a wide range of grades and are often used when machining titanium. Most carbide tools will be coated to help improve tool life and disperse heat. Carbide is the preferred tooling material for SGS end mills. We use it in conjunction with specialist coatings to provide the best quality tooling.
Ceramics are chemically inert, which makes them perfect for machining highly reactive metals. Ceramics are also very heat resistant and hard, which means they can be used at high speeds. The only problem with ceramics is their fragility. Ceramics are vulnerable to thermal and mechanical shock, and many experts considered them unpredictable under unfavourable conditions.
To find out which tooling is best for your job, try using the Taylor tool life equation. This can be written as V(T)to the Nth power=C Where V is the cutting speed in meters per minute, T is the tool life in minutes, C is the cutting speed for a tool life of one minute and N is the Taylor exponent. This formula is used by businesses around the world to calculate which tool and tooling material best meets their needs. It is also a quick way to rule out materials that are not suitable for your purposes.
This will give you an approximation of your tool life, which can help you to find the best tooling for your job. For most titanium machining the tooling of choice is coated carbide as this combines long tool life with quality results.