In the automotive and aerospace industries, the CQI-9 guidelines dictate the requirements of the AMS 2750 standard, which is designed to address the pyrometric requirements to be met by heat/thermal treatment equipment. The requirements of the guidelines include temperature sensors, instrumentation, heat/thermal treatment equipment (furnaces), tests on the accuracy of the systems and research on temperature homogeneity. All of the above is necessary to ensure that parts, materials or raw materials are heat treated to standards. To ensure that your process complies with the guidelines of these standards, we present below the importance of ensuring the temperature homogeneity of the heat treatment equipment and the validation of the furnace according to CQI-9 and AMS 2750F for the above requirements. In connection with the above, we will also discuss the appropriate use of temperature sensors designed for this application.
The CQI-9(Special Process Heat Treat System Assessment and Calibration) guidelines define the requirements for heat treatment in the automotive industry and are essential to ensure the quality of the treated product. In this respect, it is necessary to regularly monitor the performance of the thermal treatment equipment in order to ensure temperature homogeneity (TUS) and the systems accuracy testing (SAT) methodology. The CQI-9 guidelines define requirements that specify the frequency of TUS at least once a year. For aluminium parts, the required frequency of validation is every 6 months, while SAT is usually required quarterly.
In the latest revision of the AMS 2750F aeronautical standard, issued in June 2020, a number of changes have been made to address concerns about the use/reuse of thermocouples and the type of controls required to protect them from creep (“drift”). These requirements are further specified in section 3.1.4.4, which states:
“User procedures shall control the frequency of replacement of sensors in heat treatment equipment, including limits on the maximum lifetime and/or number of uses, based on supporting data such as SAT (Accreditation and Testing System) , TUS (temperature homogeneity measurement) and recalibration and/or analysis.
The client has been challenged by the client to take into account CQI-9 compliance in the manufacturing process of the product. The latter also require audits.
ELPRO LEPENIK experts have carried out the following operations at the client’s site for the full coverage of the CQI-9 standard:
Replacement of existing thermocouples with calibrated thermocouples (calibration in our accredited laboratory);
the replaced thermocouples are of the “on-site” design, whereby, through a calibration port and with a reference calibration sensor, they allow user verification of the temperature during operation (on-site) and whereby the customer meets the requirement for monthly verification;
Simulation of thermocouple to display/controller – verification of cable connection and display, accredited;
mapping or checking the homogeneity of the temperature in the furnace, in 20 points.
For independent monitoring of the furnace temperature, we can supply you with measuring equipment in REFERENCE SET consisting of:
The validation reference set is supplied according to the customer’s application or field of use.
ELPRO LEPENIK, as an example of good practice, offers a solution to ensure temperature homogeneity (furnace validation) in all types of industrial furnaces, for the temperature range.
Furnace validation can be carried out according to the customer’s internal requirements or in accordance with standards. Based on the review, we produce a validation report with a graphical presentation of the results. Benefits for the user:
behaving and acting on accurate temperature data;
has a tremendous impact on product quality by reducing temperature fluctuations and overruns;
Extending the lifetime of the furnace by eliminating the stresses on materials caused by temperature overruns;
shortening or optimising the process;
a major impact on energy efficiency and energy cost savings;
Reduced maintenance and labour cost savings;
taking action and planning to improve process and product quality;
Satisfied customers, reduced complaints and scrap;
extremely high impact on sustainability, demonstrating positive effects externally.
The temperature homogeneity check can be carried out in annealing and/or drying ovens, and in any chamber such as cold rooms or autoclaves.
In accordance with the CQI-9 guidelines, ELPRO LEPENIK can produce temperature sensors perfectly tailored to your application or field of use.
In ELPRO Lepenik & Co. d.o.o. Calibration Laboratory, we provide accredited temperature calibration (thermocouples, temperature gauges) in accordance with CQI-9 guidelines. You can find out more at link .
As part of our technical support services, we are carrying out a complete overhaul of the control and regulation part of the homogenisation and artificial ageing furnace to meet the CQI-9 temperature treatment requirements. More information is available at link .
ELPRO LEPENIK are experts in temperature and humidity for routine control and validation of various thermal processes.
V ELPRO Lepenik & Co. d.o.o. Calibration Laboratory we calibrate thermocouples and measuring equipment in accordance with the requirements of SIST EN ISO/IEC 17025:2017.
☏ Call us: +386 2 62 96 720
They are always available for opinions and explanations:
Aleksandra Lepenik, expert in temperature measurements
Measurement expert Zoran Lepenik
Related articles:
Calibration according to CQI-9 and CQI-11
Refurbishment of a CQI-9 homogenisation and artificial ageing oven
Energy efficiency starts with the temperature sensor
Platinum collection and reuse after recycling
Authors Rok Samec, Katarina Žunko, Aleksandra Lepenik
November 2022; revision June 2023
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