Northeast Manufacturing News • Jan 19 • Multi-Spindle Machines For High-Productivity Cellular Production

New multi-spindle, 5-axis machine tools from SW North America feature integrated robotic loading and unloading, plus vertical pallet storage for workpiece blanks and finished parts. “In addition to high-speed, high-precision machining, these plug & play manufacturing cells feature decreased commissioning time so customers can realize productivity benefits and profitability quicker,” said a company spokesperson.

“The benefits of independent cellular manufacturing include high-level availability and easily scaled capacity, all while increasing production efficiencies and lowering costs,” added the spokesperson.

“Cells are especially well-suited if a company is relying more on multi-shift operation, where one employee is responsible for several machines,” noted Wolfgang Armleder, SW Director of Development. “Independent cells can also deliver reliable tracking of quality and process data. Loading modules are an ideal basis for this because their deposit pattern is always nearly identical and outward transfer of SPC-measured parts can be planned.”

These cells consist of dual-spindle SW BA 222 or BA WO2-22 machining centers together with integrated 6-axis robot for loading and unloading and vertical pallet storage unit for blanks and finished parts. “Many conventional automation solutions consist of two-part systems requiring a good deal of time to commission and integrate into production. The SW cells by comparison are a crane-hook system for straightforward installation and set-up,” said the spokesperson. The robot is mounted overhead for increased freedom of motion and the pallet storage unit is set off to the side, allowing manual loading and unloading if needed while occupying a compact footprint.

“Components are mechanically connected and completely set up before the cell leaves SW,” Armleder added. “Coolant return, swarf conveyor and electrical installation all take place, with the result being a complete, independent manufacturing cell for customer use.”

The two-spindle BA W02-22 machining center with linear and torque motors features a compact 4 sq m footprint; shops can manufacture complex workpieces made of non-magnetic materials at high speeds. That makes this machine suitable for a diverse range of applications in precision engineering, including the watchmaking industry and impeller manufacturing in the automotive industry. Wear-free direct drives help ensure a low total cost of ownership due to maximum availability.

Linear and torque motors in the feed axes allow positioning accuracy of less than 0.006 mm, even at maximum machining speeds. The BA W02-22 achieves a Kv factor of 10 and a jerk of 1,200 m/s3 for high-precision micro movements. “Together with the low weight of the planetary axes, this reduces cycle time in comparison to conventional machines, depending on workpiece geometry,” said the spokesperson.

With a spindle distance of 250 mm, feed axes on the BA W02-22 accelerate at up to 24 m/s2 to a rapid traverse of up to 120 m/min. In the first configuration level, the HSK-A40 motor spindles reach the maximum speed of 25,000 RPM within 0.7 seconds. Chipto- chip time for a tool change is only 1.75 seconds. The double swiveling workpiece carrier allows loading the BA W02-22 in parallel to production time, increasing production efficiencies.

Together with a patented monoblock construction critical to stability and accuracy, the SW BA 222 and BA W02- 22 design makes overhead mounting of the loading and unloading robot advantageous. Since the robot can be flexibly configured for specific parts, there is freedom of movement and room for other tasks, such as integrating reclamping, labeling or scanning. The loading module is fitted with standard aluminum support profiles for holding additional devices.

The 7 kg robot can accommodate workpieces up to 100 mm x 100 mm x 50 mm up to 1.0 kg in mass, and can use multiple grippers to load and unload in parallel with machining time. For small batch sizes, manual loading can also take place. “This design features a special arc-shaped robot loading door, allowing nearly unrestricted access for all set-up tasks at the loading station,” Armleder added. “We created a special solution for this so that swarf and coolant can be reliably diverted from the entire robot area to the swarf conveyor.”

The vertical pallet storage unit can be fitted with a maximum of 24 pallets 600 x 400 mm in dimension. System runtime at 1 minute per every two workpieces is 9.6 hours, the equivalent of a 64-meter belt conveyor. In contrast to chain systems, pallet transport is based on an elevator-car approach employing a wear-free ball screw drive, allowing pallet loading and unloading at optimum and consistent heights.