The alloys described below work harden rapidly throughout machining and require extra power to cut Titanium/ hard alloy than the plain carbon steels. The metal is "sticky", with chips that tend to be stringy and strong. Machine tools ought to be rigid and used to no more than 75% of their rated capability. Both work-piece and instrument should be held strictly; instrument overhand ought to be minimized. Rigidity is mainly important when machining titanium, as titanium has a much lesser modulus of elasticity than either steel or nickel alloys. Slender work pieces of titanium tend to avert under instrument pressures causing chatter, instrument rubbing and tolerance problems.
The following speeds are for single point turning operations using high speed steel instruments. This information is provided as a guide to relative machineability, superior speeds are used with carbide tooling. The machinability rating quantifies the machinability of different types of materials. The American Iron and Steel Institute (AISI) determined machinability ratings for a broad range of materials by running turning tests at 180 surface feet per minute (sfpm) and arbitrarily assigned 160 Brinell B1112 steel a machinability rating of 100%. The machinability rating is determined by measuring the weighed averages of the normal cutting speed, surface finish, and tool life for each material. Machinability rating less than 100% is more difficult to machine than B1112 and material with a value more than 100% is easier.
The machining speeds are for single point turning operations using high speed steel tools. This information is provided as a guide to relative machineability, higher speeds are used with carbide tooling.