In the past year, a new name in metalcutting equipment has come to the fore in the UK since Whitehouse Machine Tools, Kenilworth, took over the sole sales and service agency for Spinner Werkzeugmaschinenfabrik GmbH, near Munich. It gives British manufacturers the option of buying top quality, European-built machines at prices that are more competitive than those offered by more established names.
A case in point is the Spinner TTC 300SMMCY twin-opposed-spindle, twin-turret CNC lathe. It is equipped to take 6,000 rpm driven tools in all 12 stations of both tool turrets. The upper turret has a ± 40 mm Y-axis and the option of 16 tool positions.
Available in two versions to accept either 42 mm or 52 mm diameter bar, the lathe is of a size and configuration that is proving increasingly popular for turn-milling complex parts to close tolerances. Maximum turning length and diameter are 400 mm and 250 mm respectively, although the lathe will swing parts up to 400 mm diameter.
Optionally, the turning centre can be equipped with robotic loading, unloading and storage of chuck parts. Spinner has its own, specialist company near Stuttgart that manufactures automation equipment for its machines.
The lathe design features a rigid, monoblock, cast iron bed with large, hardened and ground box guideways and oversize, preloaded ballscrews for effective vibration absorption. Installed weight of the machine is 3.5 tonnes.
Heavy cuts can be taken for elevated productivity levels, while ensuring high component accuracy, good surface finish and longevity of the cutting tips. Hard turning is also possible on this machine – an area in which Spinner excels.
Direct-drive spindles with built-in motors and an integrated liquid cooling system ensure compactness and promote dynamic rigidity, low vibration levels and greater machining quality due to the absence of a gear train or belt. The main spindle is rated at 6,000 rpm / 12 kW for the smaller bar machine and 5,000 rpm / 19 kW for the larger model. Both lathes have a 7,000 rpm / 8 kW sub-spindle.
Fast spindle acc/dec increases productivity by shortening non-cutting times. So do the very fast turret indexing time of 0.15 second and the 15 m/min rapids in all linear axes except Z, which travels at 24 m/min. Linear scales are provided as standard for the X1 and X2 axes, while absolute rotary encoders integrated into all other axis drives have a resolution down to 0.1 micron.
Control is by either SIEMENS 840D-SL Solution Line with Shop-Turn 7.x graphical user interface, or FANUC 31i ‘Manual Guide I’. Both have a 15″ colour screen and incorporate powerful shop floor programming capabilities for creating complex turn-milling cycles involving multiple live turrets and the C-axis spindles.
Web page www.spinner-video.com/drehmaschinen/spinner-ttc-300.html has a video showing some of the many advanced machining possibilities using the twin-spindle, twin-turret arrangement of the Spinner TTC 300SMMCY.
It starts with a shaft-type part held between centres being turned at the counter spindle by a tool in the upper turret, while a steady rest in the lower turret supports the workpiece. Next, balanced turning using tools in both turrets performs fast, accurate stock removal from the OD while traversing in the direction of the main spindle.
In a second sequence, a part that has been machined on the OD from bar at the main spindle is synchronously picked up by the counter spindle and parted off. Front-end drilling is performed by the upper turret on the fresh bar end at the main spindle, while simultaneously a turning tool in the lower turret machines the reverse end of the part in the counter spindle. Further simultaneous machining operations follow.