Using full adaptive control, Mitsui Seiki has developed a single platform hybrid vertical machining centre (VMC) able to create in a fully integrated cycle 3-D printed parts from scratch, add material to existing workpieces such as in the repair of expensive aerospace components as well as performing conventional subtractive cutting for material removal.
Indeed, according to Robb Hudson, Technology & Business Development Manager of Mitsui Seiki USA: “Such has been the level of development of the single platform hybrid concept that it can be extended in the near future to integrate further nozzles for laser drilling and cutting, localised heat treatment, specific surface cleaning operations for a workpiece as well as the drying of coolant residue.”
Now available through 2D CNC Machinery of Hinckley, the Mitsui Seiki Vertex 55X-H combines traditional high precision Mitsui Seiki machine tool build technology integrated with spindle–adapted laser Direct Energy Deposition (DED) / power feed nozzles. Said Mr Hudson: “The process is under full adaptive control as the workpiece is being produced thus ensuring that it is able to alternate back and forth between additive and conventional subtractive cutting cycles with the intended surface or feature being accurately maintained.”
The combined two process system uses a common adaptive programming language to enable seamless changes between say, conventional machining of internal or external features on the workpiece, then through the toolchange magazine, bring into operation nozzles as well as angle heads to enable the most suitable rates of flow for 3-D printing powder to be applied.
As a result, exact control of positioning and deposition of powder for 3-D printing can be applied through selectable laser beam profiles. Said Mr Hudson: “The benefits of the new highly productive and repeatable process is that good surface finish is maintained and due to the use of the powder bed based additive process, significant reductions over more traditional methods involving long cycle times can be achieved while preventing significant wastage of highly expensive materials.”
As the nozzles can be loaded into the tool magazine, similar to any conventional VMC, changes are performed automatically alongside normal milling and drilling tools for production cycles. For example, a workpiece can be surface machined ready for the layering of specific materials or the part can be 3-D printed to completion and then machined in normal production cycles.
Typical examples given by 2D CNC Director David Holden are the repair of aerofoil parts such as high-pressure blades, blisks and impellers typically used in the aerospace, power generation as well as oil and gas sectors. He said: “As OEM’s and designers are progressively introducing super hard materials for their part production, hybrid technology such as this becomes ideal for cost-effective repairs or even part recovery. This can enable a possible scrap component to be re-engineered and brought back into a serviceable condition.”
The hybrid Mitsui Seiki Vertex 55X-H machine range has a working envelope of 550 mm to 750 mm in X, 600 mm to 800 mm in Y and 400 mm to 750 mm in Z. Spindle speeds are available between 15,000 and 30,000 revs/min and the machine development incorporates an integrated coolant system to suit both wet and dry production cycles.
The machine design also claims an added advantage against other hybrid systems in that integrity is maintained around a common centreline between the positioning of each nozzle and the cutting tool. This feature has the benefit of ensuring the highest precision (volumetric accuracy is claimed at sub-15 microns within the working envelope) and thus accommodating any number of changes in the operational cycle between either process using the adaptive nozzle and the cutting tool.