Control Charts
Control charts are statistical tools used to monitor the stability and conformity of production processes. Quality Hub GINEZ implements control charts primarily for sólidos (solids) measurements to ensure products meet specification limits.
Overview
Control charts use two sets of limits to classify product conformity:
- Red Lines (Specification Limits): Define acceptable product ranges from standards
- Yellow Lines (Tolerance Limits): Define warning zones with 5% relative error tolerance
The control chart implementation currently focuses on sólidos measurements. pH and appearance use simpler pass/fail criteria.
Three-Level Classification System
The system classifies measurements into three conformity levels:
Measurements fall between the red specification limits.
if (avgSolids >= specMin && avgSolids <= specMax) {
solidsStatus = 'conforme'
}
if ((avgSolids >= warnMin && avgSolids < specMin) ||
(avgSolids > specMax && avgSolids <= warnMax)) {
solidsStatus = 'semi-conforme'
failedParams.push('solidos')
}
if (avgSolids < warnMin || avgSolids > warnMax) {
solidsStatus = 'no-conforme'
failedParams.push('solidos')
}
Control Limit Calculations
The system calculates control limits from product standards defined in production-constants.ts:
const stdSolids = PRODUCT_STANDARDS[record.codigo_producto]
// Red lines (specification limits)
const specMin = stdSolids.min // Lower specification limit
const specMax = stdSolids.max // Upper specification limit
// Yellow lines (tolerance limits with 5% relative error)
const warnMin = specMin * 0.95 // Lower tolerance limit
const warnMax = specMax * 1.05 // Upper tolerance limit
The 5% tolerance is calculated as a relative percentage of the specification limits, not an absolute value. This means tolerance ranges scale proportionally with specification ranges.
Visual Representation
Yellow Line (warnMax = 1.68)
───────────────────────────
Red Line (specMax = 1.6) ← Upper Spec Limit
═══════════════════════════
CONFORME ZONE
═══════════════════════════
Red Line (specMin = 1.4) ← Lower Spec Limit
───────────────────────────
Yellow Line (warnMin = 1.33)
Measurement Processing
The system averages two sólidos measurements when available:
let avgSolids: number | null = null
if (record.solidos_medicion_1 !== null && record.solidos_medicion_2 !== null) {
avgSolids = (record.solidos_medicion_1 + record.solidos_medicion_2) / 2
} else if (record.solidos_medicion_1 !== null) {
avgSolids = record.solidos_medicion_1
}
Implementation Reference
The complete control chart logic is implemented in lib/analysis-utils.ts:51-73:
let solidsStatus: ConformityLevel = 'na'
if (avgSolids !== null && stdSolids &&
stdSolids.min !== undefined && stdSolids.max !== undefined) {
const specMin = stdSolids.min // Red line (lower)
const specMax = stdSolids.max // Red line (upper)
const warnMin = specMin * 0.95 // Yellow line (lower) - 5% tolerance
const warnMax = specMax * 1.05 // Yellow line (upper) - 5% tolerance
if (avgSolids >= specMin && avgSolids <= specMax) {
// Between red lines = CONFORME
solidsStatus = 'conforme'
} else if ((avgSolids >= warnMin && avgSolids < specMin) ||
(avgSolids > specMax && avgSolids <= warnMax)) {
// Between red and yellow lines = SEMI-CONFORME
solidsStatus = 'semi-conforme'
failedParams.push('solidos')
} else {
// Outside yellow lines = NO CONFORME
solidsStatus = 'no-conforme'
failedParams.push('solidos')
}
}
Best Practices
- Monitor trends: Watch for patterns of Semi-Conforme results approaching No Conforme zones
- Investigate outliers: Any No Conforme result should trigger immediate investigation
- Calibrate equipment: Regular calibration ensures accurate sólidos measurements
- Document deviations: All Semi-Conforme and No Conforme results require documentation
