IMS / NASA-Bearing — fault classification from the envelope spectrum (reasoning track)

Second signal dataset in the AI4Manufacturing FORGE corpus (Category C, task T-C1), from three run-to-failure experiments. Each record is the envelope spectrum of a 1 s vibration window with fault frequencies marked — the representation for faithful compute-then-check CoT. reasoning is empty; a planned IMS-annotated sibling will fill it (not yet published).

Records: 542 (splits {'train': 434, 'test': 108}); labels {'normal': 195, 'inner_race': 36, 'ball': 30, 'outer_race': 281}; evidence_tier {'confirmed': 542}.

Schema (7-field unified record)

field	meaning
query	the classification instruction (one of 30 deterministic paraphrases per representation)
image	the rendered signal image (bytes embedded)
annot	gold fault class: normal / inner_race / outer_race / ball
reasoning	chain-of-thought (empty here; a planned -annotated sibling will fill it — not yet published)
cate / task	C / T-C1 (signal fault classification)
metadata	JSON string: representation, set, timestamp, time_frac, channel, bearing, bearing_group, rpm, fs, fr_hz, features, fault_freqs, computed_verdict, computed_snr, evidence_tier, image_sha256, split

Provenance & reproducibility

Generated deterministically by forge_agent/examples/ims/convert.py (250c7e5f89) → forge_model/IMS/convert_ims.py (229ee98152); see provenance.json.

Gold = the documented end-state defect (readme / manufacturer teardown): Set 1 → bearing 3 inner-race + bearing 4 roller(ball); Set 2 → bearing 1 outer-race; Set 3 → bearing 3 outer-race. normal = the early files of each run; fault = the late files of the failed bearing (per-set window from the degradation onset). A computed evidence_tier (confirmed/weak/absent) flags detectability.

Caveats

• Evidence-gated, conflict-free release — every image supports (and never fights) its label. IMS faults are WEAK run-to-failure signatures (the dataset's own reference paper, Qiu/Lee/Lin JSV 2006, studies weak-signature detection), so we curate by a computed evidence_tier: the spectrum/reasoning track keeps only confirmed records (the label-independent envelope-spectrum detector independently finds the documented fault → faithful compute-then-check CoT); the perception tracks keep confirmed + non-conflicting weak — weak records where the detector confidently found a different pattern than the gold are dropped (notably ball windows scoring as cage: ball faults are cage-modulated, so the single-label gold and the detector legitimately disagree there).
• inner_race is the scarce class — excluded from the first release, REINSTATED here. The original band-limited detector confirmed only ~8 inner-race spectrum windows ("too few to form a class"); the current full-band demodulation search recovers IMS's weak Set-1 signature and confirms 36 windows — more than the published ball class (30) — so the same evidence standard that excluded it now reinstates it. It remains the weakest class: ~78% of its raw windows are absent-tier (dropped per-record by the gate), and Set 1 ran two degrading bearings (inner-race B3 + ball B4) on one shaft. outer_race (Sets 2-3) is the clean, strong class.
• Few distinct bearings — each fault class comes from one run-to-failure bearing, so a strict bearing-wise split is impossible within a class; the split is file-stratified. Treat cross-bearing generalization claims with care.

Source & license

Source: IMS / NASA-Bearing — NSF I/UCR Center for Intelligent Maintenance Systems (imscenter.net) with Rexnord Corp.; three test-to-failure runs on Rexnord ZA-2115 bearings at 2000 rpm. Reference: H. Qiu, J. Lee, J. Lin, J. Sound and Vibration 289 (2006) 1066–1090. Distributed via the NASA Prognostics Data Repository.