MedTech Terms
    The authoritative reference
    All terms

    Process Capability and Cpk

    Statistical measures (Cp, Cpk, Pp, Ppk) of how well a process output fits within specification limits.

    Reviewed by Christian Espinosa, Founder, Blue Goat CyberLast reviewed May 5, 2026

    Definition

    Cpk relates the distance between the process mean and the nearest spec limit to process variation. Cpk ≥ 1.33 is a common minimum target for critical characteristics; ≥ 1.67 for safety-critical attributes.

    What this means in practice

    PPAP, supplier scorecards, and process validation routinely use Cpk as a lever; 'Cpk theater' (manipulated samples) is a recurring audit concern.

    Primary references

    3 sources
    Link health: 3 verified· last checked 2026-05-09
    AIAG·1IMDRF/GHTF·1FDA·1
    1. 1
      AIAG SPC Manual
      Verified
      AIAGaiag.org
    2. 2
      GHTF/IMDRF Process Validation Guidance
      Verified
      IMDRF/GHTFimdrf.org
    3. 3
      FDA - Device Manufacturing
      Verified
      FDAfda.gov

    Inline markers like [1] jump to the matching reference above.