ISO 17025 Metrology Accreditation §6.2: Technician Competency Sheet and Eₙ Score Calculation in Excel

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ISO 17025 §6.2 requires that each technician performing calibrations be formally authorized and undergo periodic competence monitoring.

1. The 4 Audited Criteria §6.2

A. Skill Matrix

Authorization dated and signed annually by the Metrology Manager, explicitly covering the relevant instrument family.

B. Training Evidence

  • Handling and cleaning of Grade 1 gauge blocks
  • Uncertainty calculation according to GUM
  • Application of the ILAC-G8 decision rule

C. Performance Monitoring (Eₙ Score)

Annual monitoring by Eₙ Score to prove maintenance of competence.

D. Risk Awareness

The technician must verbally explain the consequences of incorrect calibration on product quality.

2. Metrological Authorization Form (Ref: TR-PERS-025)

Area of Competence Evaluation
Handling & care of Grade 1 gauge blocks ☐ Acquired ☐ To be reinforced
Mastery of uncertainty calculation (GUM) ☐ Acquired ☐ To be reinforced
Application of the ILAC-G8 rule ☐ Acquired ☐ To be reinforced
Handling of non-conformities (§7.10) ☐ Acquired ☐ To be reinforced
  • 🟢 AUTHORIZED for calibration of digital external micrometers (0-25 / 25-50 mm)
  • 🔴 NOT AUTHORIZED / Activity under mandatory supervision

3. Eₙ Score Calculation

Eₙ = |Xtech − Xref| / √(Utech² + Uref²)

  • Eₙ ≤ 1 → Competent technician ✅
  • Eₙ > 1 → Failure — retraining and suspension of authorization 🔴

Excel Formula (cell E2):

=ABS(A2-C2)/SQRT(B2^2+D2^2)

Automatic Decision (cell F2):

=IF(E2<=1;"VALID (Competent technician)";"ALERT (Too significant deviation)")

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