The drive today seems to be for people to do more in less time. For machining this tends to mean that people are looking for machines that not only have spindles that turn faster but axes that position in a virtual blur (but accurately, of course). Although some companies are providing ultrafast machining centers that utilize linear motors to move their axes around, there is some concern that, perhaps, the linear motors have some reliability problems that automotive OEMs and suppliers can ill-afford to risk. Consequently, some machine tool builders—including Mazak Corp. (Florence, KY)—are utilizing ballscrews on their axes. Don't imagine for a minute (or, in the context of this discussion of speed, "a fraction of a second") that these mechanical arrangements are in the least bit sluggish. They move like mad.
Because different folks literally need different strokes, Mazak has engineered an array of high speed machines suited for varying requirements. The one thing that they do share is their ability to provide fast cycle times. Not only does this mean that the spindles rotate rapidly and the axes fly back and forth, but that non-cut time associated with such things as tool changes are also addressed.
One of the machines offered is the FH-680, a horizontal machining center that can be used to cut either aluminum or steel. The machine has X-Y-Z motion of 1,050 × 800 × 825 mm; the table handles a 630 × 630-mm pallet. The tool taper is a CAT 50. Now here's where things really get interesting...
The machine is equipped with a 40-hp spindle drive motor that provides a top-end speed of 10,000 rpm. The spindle will ramp from 0 to 10,000 rpm in just 2.3 seconds. It can also provide 418 ft-lb of torque. The rapid traverse and maximum speed rate are 32 m/min. The tool-to-tool change time is 2.3 seconds.
Recognizing that users of the FH-680 will be using tools in a rapid-fire manner, the machine is available with the Mazak Tool Management System, which makes use of an ID chip in the toolholder. The system works by having tool data input manually once. Then the tool information is with the tool and is updated (e.g., amount of time used) without additional manual intervention; the system does the job.
Another offering is the FH-5800, a horizontal machining center with a slightly different configuration: it has a column traverse design. This means that the spindle head moves vertically and laterally. One result is that there is good access to the tool and the spindle during setup. The table in this arrangement moves in the Z-axis. So far as the move-ments go, the X, Y, Z coordinates are 710 × 610 × 660 mm. Axis acceleration is 0.7 g. The maximum cutting feed is 50 m/min. The 30-hp spindle provides a maximum speed of 12,000 rpm. Toolchanges (chip to chip) can be made in just 3.2 seconds.
To help assure that heat from chips don't affect the precision of the machined surface, there's what's called the "Niagara" coolant discharge, which really does come down in a cascade to flush the chips away from the cutting area and into a separate cooling tank.
The FF-510, which is equipped with a 400 × 400-mm table and has X, Y, Z travels of 510 mm in each axis, provides a positioning speed of 60 m/min; the acceleration is 1.0 g. The horizontal machining center features a 20-hp motor that ramps up to 15,000 rpm in 1.3 seconds. Toolchanges (chip to chip) are effected in just 2.8 seconds. Ensuring that changes are done of useful tools, there is tool breakage detection performed by the automatic toolchanger when the tool is in the standby position, not during the machining operation. Pallets can be changed in just 6.3 seconds.
And there's the FF-660. This machine handles a 500 × 500-mm pallet and has X, Y, Z travels of 660 mm in each axis. The rapid traverse rate is 90 m/min, and acceleration is 1.5 g. The top end of the spindle is 15,000 rpm; the spindle taper handles CAT 40 tools. The machine is equipped with two pallets: the pallet change time is 6.3 seconds. The machine is available with optional packages that make it suitable for cast iron or aluminum parts.