When the Hardinge Workholding Group needed a new turning center to complete the setup of a lean manufacturing cell, it didn’t have to go far. In fact, the machine it needed was being built at another Hardinge facility. The GS 200 MSY offered all the features the company considered most important: fast X- and Z-axis rapid traverse rates, high torque, a subspindle with C-axis indexing capability and sufficient rigidity and repeatability.
The machine’s brand is just a bonus, says Tom Mitchell, general manager of the Elmira, New York-based company’s Workholding Group. “Of course we try to use a Hardinge machine, but we will purchase the best machine to fit our application, no matter what brand,” he explains. He cites the following factors as setting the machine apart from other models in the same class:
• Subspindle and turret design—The GS 200 MSY is part of a cell dedicated to a family of components that begin as carburized steel slugs measuring 2.5 inches long and 4 inches in diameter. Equipped with main and subspindles, the turning center can machine both ends of these workpieces in one setup. This eliminates the need for two lathes. Meanwhile, C-axis indexing capability and turret-mounted live tools enable additional operations that might otherwise require another machine. The result is less operator intervention for loading and unloading as well as reduced floor-space requirements, cost per part and manufacturing overhead, Mr. Mitchell says.
Cell operator Britt Brewster adds that each of the turret’s 12 positions accommodates holders wide enough to grip two separate static or live tools, one for main-spindle operations and one for subspindle operations. Additionally, clearance from the back of the turret to the subspindle head wall is sufficient to enable the use of longer drills and boring bars, eliminating typical subspindle machining restraints. Together, these features reduce change-overs by enabling the company to keep the turret stocked with dedicated tooling that covers the majority of parts processed on the machine, he says.
• Traverse speed and torque—The machine’s X- and Z-axis rapid traverse rates of 1,181 ipm are 25 to 49 percent faster than those of other models the company considered, Mr. Mitchell says. Likewise, the main spindle’s dual-wound motor provides 235 foot-pounds of torque, which is said to be more than twice as much as the other models. This is critical for heavy metal removal during turning and drilling operations, he notes.
• Rigidity and maintenance—Heavy cutting requires a rigid platform, and the GS 200 MSY is said to weigh 3,800 pounds more than another machine in the same class the company had considered. Additionally, its 4,944 pounds of X- and Z-axis thrust is more than twice as much as the competing model, the company says. Mr. Mitchell adds that the machine’s linear guides provide faster motion with less friction compared to the box ways on other brands.
He says that so far, the machine has required little maintenance. For example, the company appreciates the fact that the guideways and ballscrews are greased for life instead of lubricated with oil. This eliminates the need to deal with a lube separation system, coolant contamination or oil removal.
• Chip management—Mr. Brewster says the machine’s coolant options and 280-psi pressure are important for quickly flushing chips to the conveyor to keep the cutting area clean. “In a production environment, we need high coolant pressure for turning and drilling applications,” he explains. “We have the standard headwall flush, plus through-tool coolant to help remove chips from holes and grooves, to flood the cutting edge, and to cool down the cutting area.”
• Program prove-outs—The machine incorporates FANUC’s Manual Guide I programming, which provides a fully animated simulation of operations to help programmers prove out the process before machining begins. Craig Carpenter, manufacturing engineer at the Workholding Group, adds that programmers can also use M codes to control the torque limit for synchronous part transfer from the main spindle to the subspindle. This enables the subspindle chuck jaws to bottom out and locate against the face of a part held in the main spindle during transfer without damaging the machine.