Turn, Mill And Laser-Harden In One Setup

A different breed of turn-mill machine was recently introduced at EMO 2007 in Hannover. The UniCen 504 from Monforts combines turning and four-axis milling with integral laser hardening and laser welding in one workpiece setup. The machine platform enables shops to bring often-outsourced laser treatment in-house to reduce lead times, allow better control over secondary laser operations and offer improved flexibility to respond to changing customer needs.

The multipurpose UniCen machine, which is currently available in the United States from Sunbelt Machine, Inc., is the result of a German Federal Department of Education and Research (BMBF) project. It was developed by Monforts (Monchengladbach, Germany) in cooperation with partners including the Fraunhofer Institute for Production Technology, Laserline GmbH, Precitec KG, EXAPT GmbH and Sempell AG.

The turn-mill machine can accept workpieces as long as 900 mm and offers maximum swing diameter over bed of 600 mm. In addition to its turning turret, the UniCen has a 12,000-rpm, B-axis spindle that provides ± 95 degrees of rotation for milling and drilling operations. The turn-mill’s two modular laser units—one for hardening and the other for welding—each install via HSK 63 interface into the B-axis spindle. This allows the laser units to be automatically removed from the spindle and stored outside the machining environment, protecting sensitive optical components from damage by coolant and chips during turning and milling operations.

The laser welding unit can perform deposit welding and alloying at specific areas of a workpiece. This is often done to repair worn or damaged components—weld material is added and then the workpiece feature is machined back to original specifications. The coating unit contains the optics to form and guide the laser beam in addition to a welding wire feeder and a process sensor. A coaxial gas supply protects the focusing lens against contamination during the welding process. Laser-deposit welding is said to cause virtually no workpiece distortion, as the localized absorption of laser energy causes minimal heat induction.

The laser hardening unit performs case hardening of specific workpiece features that will encounter wear due to mating components, such as bearing journals, keyways and splines. The maximum hardening depth is 1.5 mm with almost no workpiece distortion. The unit can generate a variable laser spot as large as 20 mm by 50 mm on the workpiece. This is appropriate for quenched and tempered steel, cold- and hot-forming steel, high-speed steel, stainless steel and cast iron.

The machine’s high-power diode laser source delivers a beam through a guiding system to each laser unit. All the laser and machining processes are controlled by the machine’s central control system. The control units for the laser equipment are connected via a profibus interface to the machine’s control. The machine control includes a CAD/CAM module that offers an intuitive, user-friendly interface for programming multiple operations.