Mikrosa KRONOS M 250

The Mikrosa KRONOS M 250 is a CNC production centerless grinding machine from Mikrosa — the United Grinding Group's specialist centerless grinding brand based in Leipzig, Germany — engineered for production grinding of medium-diameter cylindrical components up to 250 mm diameter in infeed mode. The '250' designation indicates the maximum infeed workpiece diameter, which significantly expands the machine's application range beyond the KRONOS S's 150 mm infeed limit. The KRONOS M 250 occupies the mid-to-large tier of Mikrosa's KRONOS platform, targeting heavy industrial components such as large bearing races, hydraulic cylinder rods, camshafts, crankshafts, and large-diameter shaft components that fall outside the capacity of smaller production centerless grinders.

The KRONOS M 250 uses a substantially larger grinding wheel than the KRONOS S — a 600 mm diameter grinding wheel versus 400 mm — which provides greater wheel life per dress, more consistent cutting geometry across the contact zone, and higher material removal rates for the larger workpiece diameters in this machine's range. The regulating wheel is correspondingly larger at 350 mm diameter, providing a wider, more stable support surface for the heavier workpieces this machine handles. Both wheels are mounted on thermally-stable Granitan mineral casting heads, providing the vibration-damping base that distinguishes Mikrosa machines from cast iron competitors in demanding production environments.

CNC control on the KRONOS M 250 is provided by a Siemens 840D sl system with Mikrosa's KRONOS-specific grinding software, which manages wheel dressing cycles for both the grinding wheel and regulating wheel, infeed rates, workpiece rotation speed through regulating wheel RPM control, and parts handling sequencing for robotic or bowl-feeder automation. The grinding software stores complete recipes for each part family — all dressing parameters, gap settings, blade height and angle, feed rates, and sparking-out cycles — enabling fast changeover between part families with program recall rather than manual setup adjustment. The KRONOS M 250's larger size requires a more substantial foundation than smaller centerless grinders, and United Grinding provides detailed foundation drawings as part of the machine installation documentation.

The KRONOS M 250 is priced in the $350,000 to $550,000 range new, reflecting the larger machine scale, bigger wheel system, and higher processing capability. This positions it as a significant capital investment justified by production volumes of large bearing and shaft components where centerless grinding's throughput advantage over cylindrical grinding remains compelling even at larger diameters. Primary buyers include automotive transmission suppliers grinding camshafts and crankshafts, large bearing manufacturers processing industrial bearing outer rings, and hydraulic cylinder manufacturers grinding large rod diameters to tight surface finish and diameter tolerance specifications.