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QualityTracking¤

Track NOK (defective) parts and quality metrics from OK/NOK counter signals.

Module: ts_shape.events.production.quality_tracking Guide: Production Monitoring

When to Use¤

Use for quality tracking on production lines. Computes scrap rates, first-pass yield, and defect Pareto by reason code per shift. Pairs naturally with the OEE calculator's quality component and with part-level tracking for per-SKU quality analysis.

Quick Example¤

from ts_shape.events.production.quality_tracking import QualityTracking
import pandas as pd
import numpy as np

np.random.seed(42)
ok_counts = np.cumsum(np.random.choice([0, 1], size=480, p=[0.05, 0.95]))
nok_counts = np.cumsum(np.random.choice([0, 1], size=480, p=[0.97, 0.03]))
df = pd.DataFrame({
    "timestamp": pd.date_range("2024-01-01 06:00", periods=480, freq="1min"),
    "ok_counter": ok_counts,
    "nok_counter": nok_counts,
    "part_id": ["PN-100"]*240 + ["PN-200"]*240,
    "defect_reason": np.random.choice(
        ["SCRATCH", "DIMENSION", "CRACK", "COSMETIC"], size=480
    ),
})

qt = QualityTracking(df, timestamp_column="timestamp")
by_shift = qt.nok_by_shift(ok_counter_uuid="ok_counter", nok_counter_uuid="nok_counter")
by_part = qt.quality_by_part(
    ok_counter_uuid="ok_counter", nok_counter_uuid="nok_counter", part_id_uuid="part_id"
)
by_reason = qt.nok_by_reason(nok_counter_uuid="nok_counter", defect_reason_uuid="defect_reason")
daily = qt.daily_quality_summary(ok_counter_uuid="ok_counter", nok_counter_uuid="nok_counter")
print(by_shift)

Key Methods¤

Method Purpose Returns
nok_by_shift(ok_counter_uuid, nok_counter_uuid) Compute NOK count and scrap rate per shift DataFrame with shift, ok_count, nok_count, and scrap_rate
quality_by_part(ok_counter_uuid, nok_counter_uuid, part_id_uuid) Break down quality metrics by part number DataFrame with part_id, ok_count, nok_count, and first_pass_yield
nok_by_reason(nok_counter_uuid, defect_reason_uuid) Pareto of defect reasons by count DataFrame with defect_reason, count, and cumulative percentage
daily_quality_summary(ok_counter_uuid, nok_counter_uuid) Daily summary with total parts, rejects, and quality ratio DataFrame with date, total, nok, and quality_ratio

Tips & Notes¤

Use monotonic counters, not deltas

Pass cumulative OK and NOK counters — the module computes deltas internally and handles counter resets. If your PLC provides per-cycle OK/NOK flags instead, convert them to cumulative sums first.

Related modules

See Also¤