Taking a turn for the better

By packaging both turning and milling functions in a single machining center, machine tool builders believe they’ve hit on a winning combination that can boost part quality while also slashing cycle times, space and costs.

Efforts to include more than one machining capability in a single machine go back a couple of decades, said Errol Burrell, machining center product specialist for Okuma America Corp., Charlotte, N.C. Why the interest in multitask machines?

Turn-Cut is a programming option that enables a horizontal machining center to create surfaces that taper, arc or change in other ways along the Z-axis of a workpiece. Image courtesy of Okuma America.

“Work space is at a premium,” said Burrell, whose company offers Turn-Cut, a programming option that adds turning capabilities to a horizontal machining center. “So, if you have a machine that does both milling and turning, now you’ve got just one machine taking up a smaller space [than two machines].”

Combining turning and milling in one machine also improves machining accuracy by allowing users to keep parts clamped in place, thereby preventing possible stack-up errors.

Additionally, splitting up milling and turning among multiple machines can require users to make four or five setups, said Simon Knecht, NAFTA region sales manager for Germany-based STAMA Maschinenfabrik GmbH. Charlotte-based Chiron America Inc. sells the company’s machines. STAMA has been building its integrated vertical milling and turning centers, called mill-turn machines, since 1999. “On the mill-turn, in the best case, you can finish in one or two clampings.”

Multiple setups on separate turning and milling machines require parts to be handled multiple times, thereby lengthening the production process, said Kelsey Hadley, a STAMA product specialist. “But by combining operations on the mill-turn machine, we can reduce the amount of part handling and the amount of nonproductive machining time.”