"Spirited performer."

Automotive Manufacturing & Production, March, 1997 by Gary S. Vasilash

"The case," Gill says, "is subjected to a series of milling, boring, drilling and tapping operations. The traditional method of machining transmission cases required several different machines. This entailed repeated setups and multiple chucking, all of which added variation to the part and time to the process."

So now they are using the capabilities of the machining centers - they have two cells in Shelbyville, one consisting of six A77s and the other with five - to replace the multitude of machines that had been required to do the various machining operations. "We are running two dozen different part numbers on those cells, a half dozen more parts than we originally intended. This variety of parts has been so easily accommodated by these cells that we are continuing to amaze ourselves with how easy it is to manufacture different part numbers," says Gill.

The A77 horizontal machining center is a machine that is ideally suited for a variety of powertrain applications, be they in transmissions, or in engine block machining, as when there are bimetallic milling requirements.

The Features. The A77 is equipped with an integral-motor spindle that runs at 40, hp and with 287 lb.-ft. of torque at 10,000 rpm. When the spindle is wound out to its maximum rpm - 18,000 - it is at 30 hp. The result is that metal removal rates of 256 [in..sup.3]/min. on aluminum and 43 [in..sup.3]/ min. on mild steel can be realized. Getting up to speed is quick, due to the integral spindle motor design, which eliminates power losses from shafts and gears: from 0 to 10,000 rpm in 2.5 seconds. To help assure that there isn't overheating of the spindle during operations, there's a built-in spindle cooling system.

The machine provides axis travels of 31.5 x 29.5 x 30.3 in. The pallet size: 24.8 in.; it can handle a load of 2,640 lb.

The rapid traverse rate is the same as the cutting feed rate: 1,180 ipm. To facilitate quickness while minimizing maintenance concerns, there are dual Y-axis ballscrews employed. Tool-to-tool time for the A77 is two seconds.

Because this machine can generate plenty of chips, the coolant and chip disposal systems are configured to handle the requirements. The machine can send coolant through the spindle at a rate of 8 gallons per minute. The chips are flushed to the rear discharge unit by a nozzle that sends out coolant at a rate of 26 gallons per minute and by 32 overhead shower nozzles that deliver 79 gallons per minute.

Although a given A77 is built just like another A77, Makino engineers realize that there are, at the end of the day, unique attributes or characteristics of particular machines that can have an effect on their performance. So after a machine is built they perform a "mapping" of each machine. The objective is to be able to fine tune the machine dynamics. This information is sent to the Makino Geometric Intelligence software in the CNC control. During operation the control "knows" what the dynamic performance of a particular machine is, and consequently there are automatic compensations, based on the mapping, made in order to provide the required output.