Comprehensive upgrade of popular Citizen lathe - Citizen Machinery

The Citizen Miyano BNJ-51SY turn-milling centre has seen a significant increase in machining functionality following an extensive reconfiguration. Availability in Britain and Ireland is through Citizen Machinery UK.

The innovative, CNC, fixed-head, automatic barfed lathe has been re-engineered from the ground up to address the demands of modern manufacturing. It offers superior rigidity, expanded machining capabilities and advanced features designed for efficient unmanned operation. It also represents a major advance in Citizen’s commitment to its EcoBalance machine philosophy, focusing on sustainability.

Central to the BNJ-51SY’s upgrade is an improved cast structure that dramatically increases machine rigidity and hence tool life, as well as minimising thermal movement, ensuring the lathe maintains high-precision performance even under demanding machining conditions.

The machine is equipped with two spindles, both capable of reaching a speed of 5,000 rpm. A key upgrade is the expanded machining area at the sub spindle side, which now allows a 51 mm diameter chuck to be mounted on the opposed spindle, matching the main spindle’s capacity. Identical chuck diameter on both sides significantly broadens the range of workpieces that can be processed in a single setup and allows a seamless, integrated approach to complex workpiece production for greater versatility and efficiency in the workshop.

A notable addition to the new, seventh-generation BNJ-51SY is the integration of Citizen’s proprietary LFV (low frequency vibration) technology. The function reduces swarf-related issues by breaking up the ribbons generated when cutting some materials into smaller, manageable fragments. Furthermore, the lathe now has simultaneous four-axis control, meaning that LFV can be used in the X and Z axes on both the main spindle and the sub spindle at the same time, allowing more convenient division of front-end and reverse-end cutting operations.

The flexible, multi-tasking machine features two turrets, with 12 live tool stations in the main turret and eight live tool stations in the second turret. The 3-axis main turret benefits from vertical Y-axis movement, while torque has been raised to 25 Nm on the second turret to match the first, ensuring stable and powerful cutting. The distance between the work spindles has been increased by nearly one-half to 825 mm, greatly expanding the size of component that can be produced. Rapid feed rates are fast – 24 m/min for the X1, X2, Z1, Z2 axes and 18 m/min for Y1 – ensuring minimal non-cutting times.

The machine is controlled by a FANUC 0i-TF Plus CNC system with a 10.4-inch colour LCD screen. Standard NC functions include collision detection, automatic power-off, a tool offset capacity of 128 pairs, and various interpolation and turning, milling and drilling functions. LFV modes, geometry support and a power consumption monitor are included.

Optional features like a spindle brake, an in-machine unloader for automated workpiece transfer, a chip conveyor, and various air blasts and detectors ensure the BNJ-51SY can be customised to suit a wide array of specific manufacturing requirements.