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PHM 2010 milling tool wear — reasoning track (angle-folded cutting force)
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---
license: cc-by-4.0
task_categories:
- image-classification
pretty_name: PHM 2010 Milling Tool Wear Angle-Folded Cutting Force (signal→VLM, Category C)
tags:
- tool-condition-monitoring
- milling
- cutting-force
- signal-to-image
- compute-then-check
---
# PHM 2010 milling — is this cutter still fit to cut? (reasoning track)
Part of the AI4Manufacturing FORGE corpus (Category **C**, task **T-C1**), and the corpus's **first machining dataset**. Each record is one cut's **axial cutting force folded onto a single spindle revolution**: the horizontal axis is rotation angle over a full 360 degrees, the vertical axis is newtons. Three flutes cut once each per turn, so a sharp cutter shows three modest humps and a worn one shows the same three, swinging much further.
That representation is the one a stated rule can be applied to, which is why it carries the reasoning track. Only the axial force folds into a countable per-flute structure: on the same cutter and the same section, vibration's hump count moves 9 -> 6 and drifts in phase, and acoustic emission has no per-flute structure at all — only a level that rises two orders of magnitude. The other channels ship as **`PHM2010-perception`**.
**The query states the limit, and that is deliberate.** A cutter has no characteristic fault frequency to look up: tooth passing is present on a brand-new tool, because cutting *is* the periodic impact, and wear raises existing lines rather than creating one. So the question is not *which fault* but *has this crossed the limit* — and the limit is a shop-floor convention, stated rather than derived. What the image supplies is the number to compare against it. `reasoning` is empty here; the **`PHM2010-annotated`** sibling fills it.
**Records:** 858 (splits {'train': 597, 'test': 261}); labels {'serviceable': 646, 'worn': 212}; by cutter {'c1': 293, 'c4': 304, 'c6': 261}.
**What was filtered.** 87 of 945 cuts are held back from this track: those where the stated rule, applied to the image, does not land on the gold label. A record where it does not would teach a model to compute correctly and then ignore its own arithmetic. **The filter uses gold, so this track is easier than the raw dataset**, and what it removes is the boundary — cuts sitting near 74.5 N. The four `PHM2010-perception` configs are **not** filtered and carry the whole 945-cut population.
## Rig
| | |
|---|---|
| Process | dry high-speed milling of stainless steel HRC52, down-milling |
| Cutter | 3-flute tungsten-carbide **ball-nose** end mill, 6 mm diameter |
| Cut | 0.2 mm axial depth, 0.125 mm radial depth, 10400 rpm, 1555 mm/min feed |
| Sensors | Kistler 3-axis dynamometer + 3-axis accelerometer + acoustic-emission RMS |
| Sampling | 50 kHz, 7 channels; a cut is 2.5-5 s |
| Population | 3 instrumented cutters x 315 cuts = **945 records** |
| Wear label | flank wear VB per flute, read offline on a LEICA MZ12 microscope |
## Schema (7-field unified record)
| field | here |
|---|---|
| `query` | the paraphrased question; for the reasoning track it also states the decision rule |
| `image` | the rendered PNG, bytes embedded |
| `annot` | `worn` or `serviceable` |
| `reasoning` | `None` — filled by the annotation pass, not here |
| `cate` / `task` | `C` / `T-C1` (signal fault classification) |
| `metadata` | JSON: cutter, cut index, measured period and rpm, wear in um (all three flutes), the measured peak-to-valley and the threshold it was compared with, split |
## Splits
`train` / `test` = **by cutter**, never by cut. See caveats 1-2 for why a per-cut split is not usable on this dataset.
## Provenance & calibration
Produced by `forge_agent/examples/phm2010_milling/convert.py` (forge_agent `e8726e30f2`) and packaged by `forge_model/PHM2010/convert_phm2010.py` (forge_model `7985ec9066`).
**Gold.** `worn` = mean flank wear >= **125.0 um**. Chosen by us, from label-only properties; see caveat 3.
**The measurement in the query.** Peak-to-valley of the angle-folded axial force. The threshold, **74.5 N**, is fitted on the TRAIN cutters (c1, c4) only and applied blind to c6 — the same discipline as this corpus's other calibrated gates. Fitting it across all three cutters instead reaches a flattering number by fitting on the test set; both are recorded in `provenance.json`.
| cutter | cuts | rule agrees with gold | majority baseline | missed worn | false worn | |
|---|---|---|---|---|---|---|
| `c1` | 315 | 93% | 71% | 22 | 0 | train |
| `c4` | 315 | 97% | 78% | 0 | 11 | train |
| `c6` | 315 | 83% | 59% | 54 | 0 | **held out** |
The threshold does not transfer cleanly between cutters — per leave-one-out fold it lands at different values, because the three cutters' healthy baselines differ about fourfold. That is a property of the rig, and it is why the rule is absolute newtons rather than a ratio to a cutter's own first cut: at equal wear the ratios spread 3.5x while the absolute forces spread 1.5x.
**Query pool.** Domain `cutting_force`, angle_profile 30, spectrogram 30, scalogram 30, waveform 30, reshaped 30 paraphrases.
## Caveats
1. **The wear labels are interpolated, not measured per cut.** The archive ships 2835 values and the source paper says each cut was read under a microscope. The values do not support that: none ever decreases, 231 repeat the previous cut exactly, and two of the nine flutes are reproduced to 0.0017 um by piecewise-linear interpolation through 15 cut indices. The test that settles it is not monotonicity — NASA Ames' genuinely per-cut-measured milling set is monotone too, at a *higher* rank correlation — it is predictability: hide a value and predict it from its neighbours, which costs 0.0017 um here and 12.5 um there, a factor of 7494. A microscope does not read to a thousandth of a micrometre.
2. **Which is why the split is by cutter and the cut index never appears in an image.** On a random per-cut split a nearest-neighbour model that reads no sensor at all matches the published deep models. Nothing rendered here encodes how far into a cutter's life a record sits.
3. **The wear threshold is ours.** The archive contains no threshold, no pass/fail column and no documentation — it was a regression challenge scored in micrometres. ISO 8688-2's 300 um end-milling criterion is never reached (the run stopped at 315 cuts; worst flute 234.7 um). We chose the limit from label-only properties, not from any detector's accuracy.
4. **Three cutters is at most three folds.** One is held out. This says nothing about transfer to another machine, another workpiece or another cutter geometry.
5. **The task is serviceability, not wear regression.** Predicting the micrometre value on this dataset trains the interpolation formula back.
## Source & license
PHM Society 2010 Data Challenge, milling tool wear. Rig and protocol: Li X, Lim B S, Zhou J H *et al.*, *Mechanical Systems and Signal Processing* **23**(8), 2009, `doi:10.1016/j.ymssp.2009.06.008`. The official distribution host has lapsed; the archive used here is a byte-identical mirror, verified against four independent copies of the label files.