Mikrosa Kronos M
Key Specifications
max workpiece diameter through feed
max workpiece diameter in feed
grinding wheel diameter
regulating wheel diameter
grinding wheel speed
throughput reference
Overview
The Mikrosa Kronos M is a CNC centerless grinding machine from Mikrosa, the United Grinding Group member that is the global leader in centerless grinding technology. Centerless grinding is a high-production grinding process for rotationally symmetric components — bearing races, hydraulic cylinders, valve stems, fuel injector needles, and precision shafts — where the workpiece is supported between the grinding wheel and a regulating wheel without center or chuck fixtures, enabling continuous through-feed or in-feed grinding at rates impossible with conventional cylindrical grinding.
The Kronos M is Mikrosa's mid-range centerless grinder, designed for production grinding of components up to 100 mm diameter in through-feed mode and up to 150 mm in in-feed mode. The machine's centerless grinding process excels where three conditions apply: the part is rotationally symmetric, production volumes are high (hundreds or thousands of identical parts per shift), and surface finish and roundness are critical (Ra 0.1-0.4 µm, roundness < 0.002 mm). Automotive bearing manufacturing is the primary application — virtually every ball and roller bearing race in modern vehicle manufacturing passes through centerless grinding at some point in its production.
Mikrosa's Kronos M uses a CNC-controlled grinding wheel head, regulating wheel head, and work rest blade angle with servo-adjustable gap setting between the grinding and regulating wheels. This CNC configurability enables rapid changeover between different part diameter families by reprogramming wheel gap, blade height, and regulating wheel angle rather than physical tooling changes. For production facilities running multiple part families on the same machine, this CNC flexibility significantly reduces changeover time compared to conventional mechanical-setup centerless grinders.
At $300,000-$500,000 new, the Kronos M competes with Cincinnati Milacron and Koyo centerless grinders in the mid-range production segment, with Mikrosa's United Grinding service network and C.O.R.E. platform integration providing ecosystem advantages for multi-brand grinding facilities.
Full Specifications
| Parameter | Value |
|---|---|
| Max Workpiece Diameter Through Feed | 100 mm (3.9 in) |
| Max Workpiece Diameter In Feed | 150 mm (5.9 in) |
| Grinding Wheel Diameter | 400 mm (15.7 in) |
| Regulating Wheel Diameter | 250 mm (9.8 in) |
| Grinding Wheel Speed | Up to 63 m/s |
| Throughput Reference | Up to 1,000 parts/hour (small bearing races) |
| Roundness | < 0.001 mm |
| Surface Finish | Ra 0.05 - 0.4 µm |
| CNC Control | Fanuc with C.O.R.E. platform |
| Machine Weight | ~5,500 kg (12,125 lb) |
Strengths & Limitations
Strengths
- Through-feed centerless grinding achieves throughputs up to 1,000 small parts per hour — far exceeding cylindrical grinding rates
- Centerless support eliminates workpiece deflection, enabling high-precision roundness (< 0.001 mm) on long slender shafts
- CNC-adjustable wheel gap and regulating wheel angle enables fast changeover between part families without mechanical disassembly
- Mikrosa is the global reference for centerless grinding — widest installed base in automotive bearing and shaft manufacturing
- Ra 0.05 µm achievable for bearing race applications requiring ultra-fine surface finish
- C.O.R.E. platform integration for facilities running Studer, Schaudt, and other United Grinding brands
Limitations
- Centerless grinding requires matching wheel gap, regulating wheel angle, and work rest height to each part diameter — process setup requires experienced grinding engineers
- Through-feed mode requires straight cylindrical form — parts with features (shoulders, tapers) require in-feed mode and longer cycle times
- Centerless grinding produces a slightly lobed form (odd-numbered lobes not detectable with two-point measurement) requiring 3-point or V-block measurement for accurate roundness assessment
- $300K-$500K requires high production volume of suitable parts to justify over cylindrical grinding
Best For
Frequently Asked Questions
01
Through-feed centerless grinding feeds the workpiece axially through the gap between the grinding wheel and regulating wheel — the workpiece enters one side and exits the other side with the OD ground. This mode is used for straight cylindrical parts without flanges or shoulders. The regulating wheel is angled slightly to provide the axial feed force. In-feed centerless grinding holds the workpiece at a fixed axial position while the grinding wheel advances to remove material — used for parts with non-cylindrical features (tapered ODs, multiple diameters, flanged ends). Through-feed is faster; in-feed handles more complex geometries.
02
Centerless grinding achieves 5-10x higher throughput than cylindrical grinding for bearing race ODs, with comparable or better roundness. Since the workpiece has no chuck or center to create runout, centerless grinding naturally corrects roundness errors — each revolution of the workpiece averages out the previous roundness, converging on a near-perfect cylinder. This self-correcting roundness behavior, combined with the through-feed ability to process hundreds of parts per hour, makes centerless grinding the standard process for bearing race production.
03
The work rest blade height and angle are determined by the part diameter, the ratio of grinding to regulating wheel diameters, and the desired roundness correction rate. For production centerless grinding, these parameters are calculated from Mikrosa's application charts or process simulation software and verified by trial grinding. A higher blade position (above centerline) corrects lobing faster but risks instability; lower positions are more stable but correct roundness more slowly. Mikrosa's application engineers provide setup parameter recommendations for new part families.
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