Makino horizontal machining centre is for efficient machining of titanium parts

Makino says the T2 is able to hog up to 500 cubic cm of Ti-6Al-4V per minute and will be capable of much higher metal removal rates when cutting tool technology catches up. Even so, current metalcutting performance is described as five times faster than the industry average. As well as an impressive roughing performance, the machine is also capable of 5-axis simultaneous finishing to very high precision, says Makino The T2, which has a 2,000 by 2,000 by 1,800 mm working envelope and a compact 7 by 9.8 m footprint, incorporates a significant technological advance in that it has three rotary CNC axes. The ±110° A-axis and 360° C-axis are on the spindle head, while the B-axis table also provides 360° of continuous movement. Only two of the three rotary axes can be interpolated simultaneously with the linear axes. The user is able to choose A/C mode and position the B-axis for machining airframe parts, for example. Alternatively, the user can select A/B for efficiently machining engine casings and other circular components, in which case the C-axis is indexed and locked. In either case, the sixth CNC axis can be repeatedly repositioned during a machining cycle. Benefits of being able to choose between the 5-axis modes to suit the job include reduced cycle times and better surface finish, says the company. There are numerous requirements when designing a machine suitable for prismatically machining titanium. The principal ones being: high feed forces and a rigid structure to counter those forces; good damping to resist vibration; a dynamically stiff, high torque spindle; and high volume coolant delivery for efficient cooling at the point of cutting and rapid evacuation of swarf. Makino believes it has delivered a commercially viable solution which includes automatic pallet change and integrated pallet transfer and storage options. The T-Series machines, which include the larger T2.5 and T4 models, are claimed to offer a nine-fold increase in tool life when cutting titanium compared with typical gantry-type machining centres. In addition, the technology allows four times faster surface speeds to be used. The T2's HSK-A125, integral-drive spindle is Makino's most powerful to date, providing 1,000 Nm of continuous torque (1,500 Nm peak) up to 1,000 rpm, 150 kW of power and a tool clamping force of 9.8 tonnes – all values significantly higher than for previous integral-spindle motors. The 4,000 rpm (optionally 8,000 rpm) spindle is of compact, 2-axis design and is supported by a generously sized (150 mm diameter) roller bearing at the front to ensure high rigidity. Absence of gears helps to minimise vibration as well as reduce energy loss, making the machine less expensive to run. Direct drive from the induction motor is more compact than if a gear train were to be used and offers twice the moment of inertia, smoothing entry of the cutter into the material and its subsequent exit. The A-axis is driven through dual helical gears from both sides rather than just one, allowing a continuous cutting force of up to 20 kN, so no longer is this rotary axis the weak link in the 5-axis chain.