Movable gantry milling machine Four-Star SDW series

The SDW series by Four-Star is a range of fixed-table gantry milling machines with sliding columns and moving cross-rail, extending the SD series architecture with the W axis for vertical cross-rail travel between 1,000 and 2,000 mm, increasing the working height range without repositioning the workpiece.

The cross-rail is positioned by a free-position synchronous servo system (Patent M503282) at any point within the W travel, with the beam manufactured as a single one-piece casting (Patent M498072). Each column incorporates 3 linear guideways and 1 positioning rail (Patent M511389) to ensure movement precision. A distinctive feature is the free-position ATC system: the tool magazine travels independently along the X axis and performs tool changes at any position in the travel range, regardless of the gantry's working position. On SDW-48 and larger models, both X and Y axes use rack-and-pinion drive.

X-axis travel ranges from 6 to 36 m; Y-axis from 2,400 to 5,400 mm; Z-axis from 800 to 1,400 mm; and W-axis (cross-rail) from 1,000 to 2,000 mm. Column spacing covers 2,450 to 5,450 mm, with a fixed table whose length equals the X travel. The spindle operates at up to 6,000 rpm and 22/26 kW (continuous/30 min). The 32-tool ATC magazine is standard equipment. Positioning accuracy is ±0.015 mm, with repeatability of ±0.003 mm.

A distinctive option is built-in or removable CNC rotary tables from 1 to 3 m in diameter (indexed or simultaneous to 0.001°), combinable with W-axis positioning and 5-axis simultaneous milling heads for complex machining in a single setup.

The SDW series targets manufacturers machining large workpieces with complex geometries or significant height variation — turbines, energy components, large marine structures — where dynamic cross-rail adjustment maximizes effective spindle reach across each operation.