Danobat GS 400

OD (external) cylindrical grinding machines like the GS 400 are optimized for grinding the outer diameter of shafts and rotational parts held between centers or in a chuck. Universal cylindrical grinders add an internal grinding spindle attachment (ID grinding head) that allows bore grinding in the same machine setup, enabling shops to grind both the OD and ID of a workpiece (such as a bearing ring or sleeve) without re-clamping. The GS 400's OD-focused platform provides a stiffer, simpler grinding configuration optimized for external cylindrical work, while a universal machine trades some OD stiffness for the added flexibility of combined OD/ID grinding.

Polymer concrete (also called mineral cast or Granitan) is a composite material made from aggregate bonded with epoxy resin. It offers 8–10x better vibration damping compared to cast iron of equivalent mass, significantly reducing the transmission of external floor vibrations and machine-generated vibrations through the grinding spindle to the workpiece. This damping directly improves achievable surface finish — the grinding wheel stays in continuous, stable contact with the workpiece rather than chattering. Polymer concrete also has lower thermal conductivity than cast iron, reducing temperature-driven dimensional drift during long grinding runs. Most premium European cylindrical grinders use polymer concrete or mineral cast machine bases for these reasons.

The GS 400 grinds hardened and unhardened ferrous materials (carbon steel, alloy steel, tool steel, cast iron) and non-ferrous materials (aluminum, brass, bronze) using appropriate wheel specifications. Precision grinding applications typically involve hardened steel (58–64 HRC) such as bearing steel, carburized transmission shafts, and tool steel components. For hardened steel, conventional aluminum oxide or CBN (cubic boron nitride) wheels are used depending on production volume and required surface finish. CBN wheels offer dramatically longer wheel life in high-volume production of hardened steel but require higher wheel cost and proper machine speed and coolant setup.

In-process gauging uses a contact gauge (measuring probe) that remains in contact with the workpiece OD during the grinding cycle, continuously measuring the actual diameter being ground and feeding the real-time diameter data back to the CNC control. The control uses this feedback to automatically stop infeed when the target diameter is reached, compensating for wheel wear and machine drift without requiring the operator to manually measure and adjust. The GS 400 supports optional in-process gauging from Marposs, Renishaw, or similar gauge suppliers — this option is strongly recommended for high-volume automotive production where consistent size tolerancing (±0.003 mm or tighter) is required with minimal operator intervention.

The Studer S31 (United Grinding Group, Switzerland) is the market-leading mid-size cylindrical grinder in the 1,000 mm center distance class and sets the benchmark for precision, software capability (StuderGRIND), and brand recognition globally. The GS 400 competes at a similar specification level — similar between-center distance, comparable achievable tolerances — at a lower purchase price than the S31. The Studer S31's StuderGRIND programming software is widely regarded as the most capable cylindrical grinding programming environment available, while Danobat relies on Fanuc or Siemens grinding cycles. For North American shops, the Studer/United Grinding service network is considerably stronger. Danobat's advantage is primarily price competitiveness and availability through European automotive supply chains.