Capable combos: Turning Performance

Like their predecessors, the latest multitasking machines handle two or more processes, each of which traditionally would require a different machine. As always, combining processes in one of these models reduces overall setup time and floor space occupied by machines while also eliminating inaccuracies that result from moving parts from one machine to another. What’s new, however, are a host of features and innovations aimed at making the current crop of multitasking machines more capable and easier to use than before.

In the machining industry, the word “multitasking” usually brings to mind machines that can handle both turning and milling. These include lathes that can mill, normally referred to as turn/mill machines, and mills that can turn, usually called mill/turn machines, said Jeff Wallace, general manager of national engineering at DMG Mori USA Inc. in Hoffman Estates, Illinois. He said turn/mill machines offer very long x-axis travel like a lathe, making them a good choice for creating lengthy components that need both turning and milling. On the other hand, he said, shorter components that require both operations might be a better fit for mill/turn machines.

The NTX 2000 machines workpieces with complex geometries. Image courtesy of DMG Mori USA

DMG Mori USA’s latest lathe-based multitasking machines are a refresh of the company’s NT series. Among the features offered by these NTX machines are software programs called technology cycles, which make it easier for users to program the machines for special tasks, such as gear hobbing. Instead of programming a hobbing sequence by entering traditional commands, users simply enter relevant data into a table via a human-machine interface. Then the technology cycle takes over, producing the G code needed to cut a part. The business now has 42 such programs in its technology cycle library.

New Option

A more recent development from DMG Mori USA is its new DMU/DMC 65 H monoBlock mill/turn machine for complete machining up to 1,200 rpm. For greater stability, this machine features stiff construction from one casting. The machine also includes a telescoping spindle for faster movement.

“A traditional mill of that type moves a large, heavy column that carries the spindle,” Wallace said. “But this machine just moves the spindle and carrier in the z-axis, which allows very fast acceleration and deceleration rates.”

Like all mill/turn machines, the DMU/DMC 65 H monoBlock is easier to automate than lathe-based alternatives. He said this has become more important than ever in the COVID-19 environment.

“Everybody is rethinking how they do business,” Wallace said, “and there is a much greater focus on automation and running machines even longer unattended. We offer many off-the-shelf automation solutions for mill/turn platforms. The mill/turn platform is a palletized system, so we can put a pallet changer in front of a five-axis mill/turn.”

He said turn/mill machines are more difficult to automate because individual parts rather than pallets must be moved. So parts usually require automation, such as stand-alone robotics or gantry systems.

Another trend affecting multitasking machines is the move toward Industry 4.0, which involves connecting machines and collecting large amounts of data. While this can benefit machining operations very much, it also creates complications on a shop floor.

“If you spill out terabytes of data on the floor,” Wallace said, “what do you do with it and how do you utilize the different features of a machine to take advantage of it?”

To help shop floor personnel deal with data deluges, DMG Mori USA offers Celos, a human-machine interface that the company lays on top of third-party machine controls to make them easier to use. While Celos works with all DMG Mori USA machines, he said it can be especially helpful to users of multichannel, multi-axis multitasking machines.

“There’s so much going on in those machines,” Wallace said, “but Celos makes interfacing with them a lot more straightforward.”

Twin Turrets, Short Spindle

Other companies offering new multitasking options include Sudbury, Massachusetts-headquartered Methods Machine Tools Inc. The company now sells the Nakamura-Tome JX-250 multitasking turning center, which is said to provide the largest machining envelope in its class and comes in both single and twin lower-turret configurations.

With the twin lower turrets and the upper mill spindle, “you could have three tools cutting at the same time,” said Sergio Tondato, Nakamura-Tome product manager.

Built by Nakamura-Tome Precision Industry Co. Ltd., the new JX-250 comes in both single and twin lower-turret configurations. Image courtesy of Methods Machine Tools

Like all Nakamura machines, the JX-250’s spindles don’t share guide ways. He said they are kept independent of each other to prevent transmission of vibration from one spindle to another.

“You could be doing finished turning on one spindle and heavy milling on another,” Tondato said, “so to Nakamura it’s very important that they do not share guide ways.”