A Literal "New Spin" on Hybrid Milling/Grinding Machines

Mitsui Seiki’s Vertex hybrid machine borrows a jig grinder’s motion to complement high precision five-axis milling.


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“The concept is to emulate jig grinding equipment,” says Robb Hudson, CEO of Mitsui Seiki USA, when describing a new family of Vertex five-axis hybrid vertical machining/grinding centers in booth 338519. Hudson explains that this concept is literally a “new spin” on milling/grinding hybrids, because the machines can apply a part spinning process that produces tangential planetary work spindle alignment, much like the U-axis motion of jig grinding equipment. Combine this with high speed 3+2 or full five-axis milling that is capable of 0.0003-inch (5.5 µm) precision, and the result is a machine that can carry out critical applications such as lights-out machining of die/mold, optical and tooling components, Hudson says.

The Vertex Hybrid G 55-5X machine on display has two larger siblings in the family, the 75-5X and the 100-5X. The show machine is demonstrating its capabilities with a combination of milling and grinding operations on a D2 steel plate, hardened and heat-treated to 60 to 62 HRC. A form milling tool is roughing and pre-finishing corner relief, followed by a form-grinding wheel for finishing. After a rounded triangular pocket is milled in the part’s center, a variety of grinding wheels form critical step features.

“We are claiming it has CMM-level precision because the engineered accuracy and rigidity meet volumetric calibration according to ISO10320-2 using the latest FANUC 3D volumetric compensation features, while enabling us to apply in-process 3D measuring capability traceable to the National Institute of Standards and Technology,” Hudson says. He adds that the machine’s structure, which features hand-scraped guideways, is configured to attain positioning accuracy in the X, Y, and Z-axes of 0.000040 inch (0.001 mm), ±6 arc seconds in the A axis, and ±4 arc seconds in the C axis.

“But the grinding aspect of this machine is the cool part,” Hudson says. “It’s not tacked-on. We have automatic, in-process grinding wheel dressing, size measurement and wheel calibration, plus an advanced thermal compensation system to enssure size consistency”

Hudson invites attendees to check out the machine for themselves. “They can see that this is not just a spin we put on the story.”