Loeser BF 400

Belt grinding uses a continuous abrasive belt driven over contact rolls to abrade the workpiece surface. The belt conforms somewhat to the workpiece surface (the contact roll's rubber hardness determines how much the belt follows surface irregularities), producing surface finish improvement and stock removal without the precise diameter control of centerless grinding. Centerless grinding uses a precision grinding wheel and regulating wheel to produce tight diameter tolerance (±0.005 mm) and roundness (< 0.002 mm) on the bar. Belt grinding is used for scale removal, surface finish improvement, and moderate material removal where dimensional precision is secondary; centerless grinding is used for precision diameter and roundness control. Many bar stock operations use belt grinding (BF 400) first for scale removal, then centerless grinding for precision sizing.

Stainless steel bar grinding requires abrasive belts that resist loading (clogging with stainless steel smear) and generate minimal heat. Zirconia alumina (ZA) belts are preferred for stainless steel — ZA abrasive grains are tougher than standard aluminum oxide and fracture to expose fresh sharp cutting edges rather than dulling and loading. Silicon carbide belts are used for stainless applications requiring minimum surface heat. Belt grit for scale removal on hot-rolled stainless is typically 36–80 grit; for final finish on cold-drawn stainless, 120–240 grit. Open-coat belt construction (abrasive grains spaced wider than on close-coat belts) reduces loading on sticky materials like stainless and aluminum.

Yes, with appropriate tooling and parameters. Titanium is notoriously difficult to grind due to its low thermal conductivity (heat builds up at the cutting zone) and tendency to work-harden and smear rather than cut cleanly. For titanium bar grinding on the BF 400, silicon carbide (SiC) belts in medium-fine grit (60–120) are preferred, with the lowest practical belt speed (10–15 m/s) to minimize grinding temperature and lightest practical contact pressure to prevent workpiece surface burning. Titanium generates highly flammable titanium swarf — the machine must be equipped with appropriate spark containment, fire suppression, and titanium-safe dust collection. Loeser provides titanium-safe machine configurations for aerospace bar grinding applications.

In pass-through mode, the BF 400's bar feed conveyor drives the bar stock axially through the belt grinding head zone continuously — the bar rotates in driven V-rollers while advancing axially past the stationary belt contact zone. Belt grinding head position, contact force, and bar rotation speed are CNC-programmed. Bar feed rate (axial advance speed) determines the helix angle of the surface texture relative to the bar axis and the material removal depth per pass. Multiple passes (reverse direction) with the same or different belt grit produce the target surface finish. Pass-through mode handles bars up to the V-roller conveyor length — typically 2,000–6,000 mm — far beyond the 400 mm fixturing capacity.

The Loeser BF (Belt Finish) series uses flat or curved abrasive belts running longitudinally against the bar surface to produce a longitudinal surface texture — primarily for bar stock preparation and shaft surface finishing. The Loeser RF (Rotary Finish) series uses rotating abrasive discs or pads in a face-contact geometry against the component, producing a more isotropic (non-directional) or circumferential surface texture — primarily for round component end-face finishing, bearing surface polishing, and round component decorative finishing. BF is for cylindrical OD surface finishing; RF is for face finishing and round component all-surface polishing. Some components require both operations: BF for the cylindrical surface, RF for the face surfaces.