80 percent reductions of cutting cycles, 70 percent less energy demand, up to 60 percent less material waste, and 40% reduced tool expenses - this on top of significantly reduced post-processing effort for cast, rolled and forged rings: All this is made possible with the new ring cutting process on the Giant Ring Cutter (GRC). The processing concept was rigorously honed for optimization - a product of the demanding specifications in the design document:

• extremely fast and very accurate cuts at low thermal energy input and the thinnest possible kerf loss - resulting in minimized material consumption.
• superior plane parallelism down to accuracies of a few tenth of a millimeter, at the best possible surface finish 
• high machining rigidity and precision
• superior occupational safety by reliably securing and removing the cut rings, and dry, short chips without accident hazard
• versatile plant concept with retrofit options for already installed revolver lathes and milling machines
• automation concept with the gripper arm designed for ring diameters of four to eight meters and ring weights of up to 20 tons.

The requirements profile resulted in the replacement of the previous cutting tools by a circular saw blade, installed in very rigid machine structure with brand-name products supplied by highly regarded German and Swiss suppliers. Roller guide rails and ballscrew drives supplied by Rexroth ensure the high rigidity and precision.

A prototype machine based on the patent pending process for rings with diameters up to 1,450 millimeter has been operating at full capacity since the beginning of 2011. It was also awarded the German Material Efficiency Prize: because the Giant Ring Cutter not only significantly reduces machining cycles, but also saves enormous amounts of material. The new process is capable of cutting rings made from stainless steel and alloys with diameters up to 9,000 millimeters and wall thicknesses up to 300 millimeters - dimensions that cannot be attained by bandsaws. The only previously used alternative - cutting with a cut-off blade - causes steps in the ring that need to be machined at considerable loss of material and significant effort.

With superior precision

The GRC initially uses the gripper arms to transport the blanks to the chuck. Three chuck jaws driven by a ballscrew drive supplied by Rexroth secure the ring in its cutting position during the rotating cutting motion, and ensure a clean cut. Rexroth ballscrew drives perform highly accurate feed, positioning and transport tasks with precision leadscrews, pre-tensioned and adjustable anti-backlash single and double nuts. And the rigid Rexroth roller guide rails of installation size 65 reduce vibrations such that the noise emission is a mere 70 to 74 decibel, even for the open version.