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Add and subtract

A hybrid machine incorporates generative laser deposition welding into a 5-axis milling machine

In times of ever shorter product life cycles and increasingly complex parts being produced in ever smaller production runs, additive manufacturing processes can help companies produce new innovative products more quickly. The market for additive processes has grown rapidly in the past few years. However, up until now these processes have been restricted to the production of prototypes and small complex parts that otherwise would not have been manufactured using conventional methods.

The unique combination of laser deposition welding, integrated into a 5-axis milling machine, gives the user completely new possibilities for applications and geometries. Especially large workpieces with high stock removal volumes are now possible to be machined in an economical way.

The LaserTec 65 3D offers a hybrid solution for combined additive manufacture and 5-axis milling and allows for larger parts to be produced. To enable generative manufacturing, the LaserTec is equipped with a 2-kW diode laser for laser deposition welding. On the same machine, the 5-axis milling machine, based on the MonoBlock design, also makes it possible to carry out highly accurate milling operations.

“Thanks to the fully automatic changeover between milling and laser operations, the LaserTec 65 3D is suitable for the complete machining of complex components, even with undercuts. It can be also used for repair work, the application of various coatings, for moldmaking, aerospace or even medical engineering,” explains Friedemann Lell, sales director for the LaserTec products at Sauer GmbH, a segment of DMG Mori.

Target markets for the LaserTec 65 3D include tool making and mold and die, aerospace, automotive, medical technology, oil and gas, and machine construction.

Adding large parts

In contrast to laser melting in a powder bed, laser deposition welding enables large parts to be built using a coaxial metal powder nozzle. With a deposition rate of up to 2.2 lbs. per hour, on larger components this process is up to 10 times faster than the laser generation of parts with a powder bed.

The combination of deposition and milling operations opens up completely new possibilities. The component can be built up in several steps. The building process can be alternated with milling operations. Therefore, it is possible to build parts with features that are machined in the middle of the building process. These features typically would not be possible to reach afterward with a milling cutter. This can give parts additional functionality, or enable the combination of more parts into a single module.

“In the case of structural components, where today 95 percent of the material is removed by milling, with the additive process material is only built up where it is needed. This leads to significant savings in raw materials and costs,” Lell explains.

The laser additive head, complete with powder deposition head and cooling, is attached to the standard HSK toolholder of the milling spindle. The additive head can be automatically parked outside the working area in a secure station while milling operations are being carried out. The machine and process are operated and controlled by the new DMG Mori CELOS operating panel, which is combined with the Siemens 840D CNC controller.

Using a diode laser source, the metal powder is welded in layers onto a base. The powder forms a high-strength welded bond with the base surface. The welding fuses the material without pores or cracks to form a 99.95 percent dense deposited material. The coaxial nozzle which combines the laser beam and transports the powder with an inert gas, at the same time prevents oxidation during the building process. After cooling, a layer of metal forms that can be machined mechanically.

Added benefits

One strength of this building process is that the option to successively build up layers of materials in lines of 0.063 in. to 0.118 in. (1.6 mm or 3 mm) is possible, depending on the nozzle geometry. The LaserTec machine can also be filled with two different materials, and after a changeover that takes a few minutes, the two materials can be deposited after one another.

Another important application is adding material to an existing part or body. This can be done in order to customize, add functionality and features or react to product changes. The LaserTec machine has the special capability to add material onto an existing 3D surface. Therefore, it is not always that a complete part has to be made, but value can be added to an existing part.

Large machines, such as those used for machining bulky components in the energy or aerospace industries, tend to be expensive. The possibility of carrying out roughing, deposition and finishing on a single machine therefore represents a financially advantageous solution for the customer.

Another example is the energy and oil industry where components often have to be coated with corrosion-resistant alloys to protect them against wear. Laser deposition welding provides protection for parts such as pipes, fittings, flanges and special components that are used in aggressive environments.

With a hybrid solution, machining of the base material, coating and finishing can be carried out on one machine. This results in cost savings and a reduction in production time.

Laser deposition welding has long been established as a standalone technology, but it is also ideal for incorporation into DMG Mori’s CNC machines. “The combination of chip-removal and additive processes will become more important in the future, as it opens up so many new possibilities for the user,” Lell says.

DMG Mori USA