... . Xkd21 series CNC gantry Boring & Milling machine is of double-column beam gantry lifting structure and consists of such major components as ... the machine bed, the workbench, the columns, the beam, the slide carriage box, the headstock, the ram, the milling ... the both sides and connected on top by the linkage beam, forming a closed gantry frame. The workbench moves longitudinally along ...