Rotary Engineering Corporation 1968 Expanding Mandrel, Hydraulic Expanding Mandrel, Gear Grinding Mandrel, expanding mandrel manufacturers, Clamping Solution, expandable hydraulic arbor. High precision clamping elements for modern CNC operated tooling machines. CONCENTRIC™ Rotary Clamping Technology has been one of the most innovative companies in this industry for decades. The product program includes tool clamping equipment such as clamping Arbours/mandrels and chucks in hydraulic, mechanical or hydro-mechanical design, which are used in leading mechanical engineering and industrial companies under the CONCENTRIC™ brand.