CITIZEN’S A32 DELIVERS EXCEPTIONAL CUTTING PERFORMANCE

The MACH 2008 exhibition has been selected by Citizen Machinery for the European launch of its new high performance, competitively priced Citizen A32 CNC sliding head automatic lathe. This heavy duty machine takes the philosophy of the A20, Citizen’s most successful new machine launch, into the larger material size of 32 mm diameter enabling parts up to 320 mm long to be machined in a single chucking.

The Citizen A32, like the 20 mm capacity A20, is targeted at heavier duty single operation machining cycles with a 7.5 kW main, 3.7 kW two-axis subspindle and 1 kW motors to power its driven tools. It is fast with 45 m/min rapid traverse rates, more than double previous 32 mm machines and has all the advantages of Citizen’s ‘Streamline Control’ software to minimise non-cutting times by providing axis motion overlap and direct C-axis indexing. It also introduces network control of NC programs.

To ensure high metal removal rates when cutting with two tools simultaneously, a totally new heavy duty bed casting that is very compact and with high level of torsional rigidity, means there is 30 per cent advantage added to this machine in overall rigidity to enable the creation of chatter-free and uniform machined surfaces. And, in order to cater for increased productivity, the swarf discharge volume capability has been increased significantly.

As standard 23 tools can be carried on the new machine, six for turning and four are driven for cross machining from the two-axis crosslide. In order to accommodate heavy milling, one driven tool position has higher torque and can be interchanged with a unit able to carry three face driven spindles. Mounted on a substantial overarm attached to the crosslide, are four tool positions for drilling at the main spindle and four for back drilling at the subspindle. As an option to further improve flexibility, two front and two back drilling positions are available. An independent gang tool post also carries an additional five tools for back drilling of which four can be driven. By taking advantage of the options available on the machine, with up to 27 tools can be carried on the A32.

The built-in spindle configuration for both main and subspindle extend the high accuracy, low noise, low energy advantages of the A32 and increase the stability of the machine when running up to 8,000 revs/min. To support the 40 per cent improvement in torque available larger bearings and the thickness of the spindle has also been increased.

It is the Citizen Streamline control software running on Mitsubishi hardware that enables the advantages of heavier cutting cycles to be enhanced with higher speeds, overlapped machining and the creation of smoother movements with shorter idle times. Direct C-axis indexing can also save seconds on a cycle by indexing the spindle position during its rotation.

Meanwhile, an axis overlap feature initiates the next axis movement prior to the current motion being completed. Start up times and switching times are considerably shorter with the added advantage to the operator of immediate visualisation on the screen. A high speed program check function at the control enables confirmation of syntax without the machine being operated. The highly acclaimed Citizen screen layout has also been remodelled and is now compatible with the network LAN that enables full network control of NC programs.