Measurement of CQI-9 and AMS 2750 E standards

Increasing demands on quality and stability in production processes also impose greater demands on heat treatment in industry. The furnace or heat treatment equipment must be manufactured in such a way as to reproducibly meet demanding specific requirements, eg the prescribed charge temperature. These requirements are defined by CQI-9 (for the automotive industry) and AMS 2750 E (for the aerospace and defense industries). Requirements for thermal processing equipment are eg:

  • TUS (Temperature Unifomity Survey) - measurement of temperature uniformity by prescribed number of thermocouples (TC) at the boundary and in the middle
  • SAT (Accuracy Test System) - comparison of the temperature measured by the furnace control system and the temperature measured by the test gauge (the so-called SAT difference allowed)
  • Instrumentation
  • Accuracy of the system (instrumentation), calibration of path measurements and thermocouples
  • Archiving and documenting test measurements

General requirements and instrumentation for the AMS 2750 E standard

Furnaces or ovens meeting the heat treatment accreditation process in the National Aerospace and Defense Accreditation Program (NADCAP) shall be so manufactured as to reproducibly meet the requirements of AMS 2750 E:

  • Compliance temperature range
  • Temperature uniformity class required - either class 1, 2, 3, 4, 5 or 6 (see below)
  • Temperature type - either type A, B, C, D or E (see below)
  • Uniform zone requirement - define H x W x D
  • Temperature Uniformity Survey (TUS) - required with either full or empty chamber
  • System Accuracy Test (SAT) Requirements



Furnace class:


The customer determines according to heat treatment requirements:

Furnace class

General requirements for CQI-9 standard

The special heat treatment process CQI-9 is an evaluation of the heat treatment system and must be carried out at least once a year. This standard is an annex to ISO TS 16949 according to the “customer-specific requirements” and is valid for all automotive suppliers worldwide who have concluded a quality contract in the automotive supply chain.


Offer of LAC s.r.o. 

  • Temperature measurement by calibration measuring instruments on heating equipment according to CQI-9 and AMS 2750 E standards
  • Preparation of documentation according to the relevant standard

LAC engineers are always familiar with the current state of national and international standards and their technological background. If you are interested in furnace temperature uniformity measurement services or other questions, please contact our service department:


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