| --- |
| 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) |
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| 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. |
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| 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`**. |
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| **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. |
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| **Records:** 858 (splits {'train': 597, 'test': 261}); labels {'serviceable': 646, 'worn': 212}; by cutter {'c1': 293, 'c4': 304, 'c6': 261}. |
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| **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. |
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| ## 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. |
|
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| ## 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`). |
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| **Gold.** `worn` = mean flank wear >= **125.0 um**. Chosen by us, from label-only properties; see caveat 3. |
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| **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** | |
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| 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. |
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| **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. |
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