Multiple spindles, each capable of complete part machining.
A single structure: a smaller footprint.
Let’s assume that the task at hand is production machining of aluminum or other light metal parts, such as ABS housings, brake calipers, main brake cylinders, and valve housings. Further, that the production requirement (or the production probability, inasmuch as changes are the order of the day) is such that you are considering the utilization of multiple machining centers to handle the task. Of course, an abiding consideration is space efficiency, or simply floor space requirements. And the footprints of multiple machining centers is sizable—or at least likely to be greater than the 81-in. wide and 221-in. long (and 149-in. high, although ceiling height tends not to be such a concern) that is the size of the AL 204 multiple-spindle, five-axis machining center from Alfing Corp. (www.alfing.com; Plymouth, MI). The AL 204, which is part of a series of AL models that range up to the model AL 602 (the numeric designation is based on the spindle distance, or working envelope of the X-axis, so it is 200 mm for the 204 and 600 for the 602, and the number of spindles deployed, as in four for the 204 and 2 for the 602), can be fitted with either ballscrew drives or linear motors. Those opting for the former can realize a maximum speed of 90 m/min with an acceleration of 10 m/s2; the linear drive-equipped machine has a speed of up to 180 m/min and an acceleration rate of up to 20 m/s2.
The spindles on the machine have a maximum drive capacity of 58 kW; the maximum torque is 70 Nm. The tool taper is HSK-A63. The maximum speed generated is 16,000 rpm. Each of the four boxed spindles are individually driven in their Z-axis. Each spindle motor is individually cooled. Assuming that there would be an average of 30 tools used per spindle, the AL 240 would be equipped with a 120-slot toolchanger. Toolchange time—chip-to-chip—is said to be 3 seconds. Bigger magazines are available (up to 320 tools). Also, there is the ability to add up to 8 B-axes (four on each side of an A-axis bracket) for complete part machining. The machine has a standard 160 iMB Fanuc control; a Siemens Sinumerik 840 D is an option.
As mentioned, the AL line is available with a single multi-spindle module or multiple single spindles. AL 303 is available with the three spindles; the AL 402 with two, and the aforementioned 602 with two.