Mazak Corp. (Florence, Kentucky) introduced its line of Nexus machine tools at IMTS 2002. Now the company is expanding the line with more models and different types of machines. The new Nexus machines were recently on display during the company’s Touch The Future 2004 event, which took place at the company’s facilities in Florence. The company also showcased its new lean manufacturing system.
Machine tool builders usually designate related models of the same type of machine with a name that characterizes their common features or properties. Mazak’s Nexus line is an exception. The original Nexus line included CNC turning centers and vertical machining centers. Although these machines were different types (milling versus turning), they represented the builder’s effort to design machine tools that could be manufactured efficiently, yet deliver advanced technology. According to the company, this combination of performance and attractive pricing has proven to be a timely offering for shops facing intense competition from low-cost manufacturers overseas.
The new additions to the Nexus family include models featuring multitasking capability and a horizontal machining center. The two new multitasking models are the QTN250MS and the larger QTN350M. Both turning centers feature integral spindle/motor technology on the main turning spindle. On the smaller machine, the 25-hp spindle produces a maximum 4,000 rpm with a 10-inch chuck. On the larger machine, the 40-hp spindle produces a maximum 3,500 rpm with a 12-inch chuck. The rotary tool spindle for milling, drilling, tapping and boring is 7.5 hp/4,500 rpm on the QTN250MS or 10-hp/4,000 rpm on the QTN350M.
The QTN250MS features a second spindle (6-inch chuck, 10 hp, 6,000 maximum rpm). A workpiece can be quickly transferred between the first and second headstock for a smooth, continuous operation. The QTN350M features a fully programmable tailstock, which is driven by a servomotor. According to the builder, this feature reduces setup time by 90 percent. Both machines can be equipped with an optional bar feeder, allowing users to take advantage of a novel feeder scheduling function in the control unit software. Different parts can be scheduled and cut in varying quantities out of the same barstock. Because multitasking permits each part to be machined completely, the schedule can be set to sequentially produce each part in a set or kit. The complete kit or set can be delivered at once to meet kanban (pull) production requirements, a key aspect of lean manufacturing.
The Nexus HCN-6000 is the horizontal machining center entry debuted at the event. Like other machines in the line, it features advanced integral spindle/motor technology (50 hp, 10,000 rpm maximum speed) with a 50-taper spindle. The spindle maintains a stable operating temperature in heavy-duty or high speed machining conditions because of an integrated spindle chiller unit and oil/air lubrication system for the spindle bearings. Pallet size is 19.69 inches by 19.69 inches, and maximum workpiece dimensions are 35.43 inches around and 39.37 inches high.
A significant enhancement to the Nexus vertical machining center line is found in the VCN-510C/HS model. This machine has an advanced high speed spindle with built-in motor and temperature control that delivers a top speed of 15,000 rpm in 1.4 seconds and a maximum 123 foot-pounds in torque. The high speed rapid traverse rate of 1,968 ipm at 0.7 G acceleration and 2.6 seconds chip-to-chip time helps reduce non-cutting time. The machine also provides a large machining area, with X-axis travel of 41.3 inches, Y-axis range of 20 inches and Z-axis travel of 20 inches. Overall machine dimensions, however, are 16 percent smaller than previous models.
The Nexus machine concept has spurred the builder to revamp its approach to building machine tools at its Florence plant. The company reports that it invested $20 million to implement a lean manufacturing system called Production on Demand.
“The design and production goals for Nexus were to produce machines with higher performance features that were more accurate, but still would be very reasonable in price,” says Mazak President Brian Papke. “The intent was to be able to respond quickly to changing market conditions and product design changes. Building to order on demand has resulted in significantly lower finished-goods inventory while realizing the goal of delivering Nexus machines in weeks instead of months.”
The new Integrex Palletech cell installed as part of this reorganization is emblematic of this new approach. The cell can machine more than 80 different part numbers, including spindle shafts and chucks for the Nexus machines. The four Integrex machines in the cell make parts that were previously made on 11 different machines, all requiring individual fixtures and setups. Now the machines in the cell turn, mill on multiple faces, bore, tap and complete parts in a single setup. Overall throughput time on the new cell is down 54.7 percent for shaft work and down 49.4 percent for producing chucks, the company says.