Moving into Phase 2 of its programme for Low Frequency Vibration (LFV) cutting technology, Citizen Machinery UK is launching its Miyano BNA-42GTYLFV, a 42 mm bar diameter hybrid development, moving headstock turn-milling centre.
The new machine extends the advantages of the Citizen patented LFV process from the existing 20 mm and 12 mm bar sizes of its Cincom sliding head turn-mill centre range that first featured the breakthrough in cutting technology, to extend applications and provide a greater machining capacity.
LFV has enabled a massive impact to be made to Citizen’s sliding head machine build operations with some 500 machines being installed worldwide during 2017. In the Miyano BNA-42GTYLFV moving headstock configuration it enables users to benefit by machining larger size components with the true influence of total programmable control over the size of swarf generated. It also has the benefit of creating a significant improvement in tool life and overcoming surface finish problems experienced when machining difficult materials such as super alloys, copper and plastics.
The operation of LFV is based on initiating a sequence through the servo axes of the drive system to oscillate the tool in the direction of feed in phases involving tens of microns which are precisely synchronised to the rotation of the spindle. The resulting programmable ‘air cutting’ breaks the swarf into a designated chip size which prevents ‘bird nesting’ and can be applied to turning, drilling and even threading cycles. LFV can be switched in or out of the machining cycle as required.

To ensure the cutting performance, the Miyano BNA machining platform has been significantly developed around its compact frame which is similar in area to a Cincom M32 sliding head turn-mill centre requiring just 2.3 m by 1.5 m of space. This also enhances the level of rigidity and damping while helping to maintain control over thermal influences.
For instance, plain hand-scraped slideways are used on each axis rather than the use of linear rails, special ballscrew designs and roller bearings are employed on the X1 cross-feed axis to the headstock while a special lubrication system is included with hydraulic clamping without the use of a guide bush.
For machine control, the well-proven and advanced Cincom operating system is interfaced to the Mitsubishi based control platform incorporating Citizen’s ‘Superimposition’ which allows simultaneous cutting with up to three tools to maximise cutting efficiency and shorten cycle times. As a result, part programming is also straightforward using the same data format as Citizen’s sliding head range.
The machine is configured with two spindles with a 3-axis X1, Y1 and Z1. It has 42 mm diameter, 11 kW 6,000 revs//min headstock and 34 mm diameter, 5.5 kW 5,000 revs/min 2-axis X3 and Z3 sub-spindle. The maximum machining length is 110 mm and up to 45 tools can be carried on the machine.
It has a single eight-station 3-axis X2, Y2 and Z2 turret with 1 kW power, 6,000 revs/min driven tools. The turret has a half-indexing capability enabling up to 16 tools to be employed. Also, using the range of optional multi-holders for tools, the number of tool positions can even be further increased. There is also a gang tool slide with 13 tool positions of which three can be driven, powered by 1.5 kW, 6,000 revs/min motor.