Machine Tool Vibration Acceptance Checker

Per ISO 10816, up to 0.71 mm/s RMS is new-machine condition (zone A) and up to 1.8 mm/s is acceptable for unrestricted long-term operation (zone B). Between 1.8 and 4.5 mm/s the machine should be scheduled for corrective maintenance (zone C), and above 4.5 mm/s vibration is severe enough to cause damage (zone D).

Isolation and distance, in that order. Measure floor vibration at the grinder feet during press strokes; if velocity exceeds a few tenths of a mm/s in the band that matches the chatter spacing, install tuned isolation mounts or an inertia block, and don't bolt the grinder rigidly to a floor shared with impact machines.

On the spindle housing and the slideway/column while the machine idles at test speed — as close to the bearing as possible, on stiff metal (never on covers or guards). Take horizontal, vertical and axial readings if you can; use the highest for the ISO grade and always re-measure at the same spot, load and speed.

The usual suspects are floor-transmitted vibration from neighbouring machines, unbalanced tooling, worn spindle bearings, and ballscrew/servo-induced vibration. A frequency spectrum tells them apart: imbalance shows at 1× running speed, misalignment at 2×, bearing defects at non-synchronous frequencies, and looseness as a raised noise floor with harmonics.

Velocity in mm/s RMS, 10–1,000 Hz. ISO 10816 zone tables are defined on broadband RMS velocity because it weights low- and high-frequency faults evenly for general machines. Acceleration (g) suits high-frequency bearing analysis and displacement (µm) suits low-speed machines, but neither maps onto these zone boundaries.