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Manufacturers of products are not only interested in low-cost manufacturing, but also in the consistently high quality of their products. Of course, this also includes in particular a reproducible heat treatment at a high level and this depends primarily on whether the products are always heated up at the same speed and always brought to the same final temperature. In order to achieve this, the furnace used must have comparable temperatures at all positions in its usable space and this is precisely specified in DIN 17052-1, CQI-9 and AMS 2750.
This standard specifies in several quality classes how precise the temperature uniformity in the unloaded usable space or on the product must be during the steady state and how this must be determined.
This means that either the empty furnace is heated to its working temperature and then the uniformity is measured and documented at several points in the furnace (different numbers depending on the size) or that a representative product is fitted with several sensors and then heated to the working temperature.
The standard specifies the position and the minimum quality of the sensors, as well as a recommendation of the quality class to be selected.
Example: A furnace up to 300 °C for the annealing of non-alloy steels should have the quality class C and therefore achieve a uniformity of +/-10K.
In practice, a uniformity of +/-5K has proven to be sufficient in the vast majority of cases – which is why all Airtec furnaces satisfy this value as standard. This means that we lie exactly between quality class A and B in the standard and therefore offer the best compromise between price and performance – but can, of course, also deliver furnaces with quality class A or even better at the request of the customer.
CQI-9 is not a German standard but a standard developed by the Automotive Industry Action Group (AIAG) for the automotive industry and its suppliers. In this standard, not only the quality of the furnace – similar to DIN 17052 – is specified in terms of uniformity but also the regular inspection of these by so-called SAT and TUS measurements. It stipulates how precise the temperature uniformity in the unloaded usable space or on the product must be during the steady state and how this must be determined, as well as the exact structure and accuracy of the measurement chain and the periodic repetition of the measurements.
This means that either the empty furnace is heated to its working temperature and then the uniformity is measured and documented at several points in the furnace (different numbers depending on the size) or that a representative product is fitted with several sensors and then heated to the working temperature.
CQI-9 specifies the position and quality of the sensors or the entire measurement chain, as well as a specification of the maximum deviation.
Example: A furnace for solution annealing or ageing of aluminium must achieve a uniformity of +/-5K; a furnace for annealing aluminium must achieve +/-15K.
As Airtec furnaces achieve a uniformity of +/-5K as standard, you are always safe when working with our products in the automotive sector. If you have specific, more demanding requirements, do not hesitate to contact us – we are also happy to supply systems that meet even higher requirements.
AMS 2750 is not a German standard but a standard developed by SAE Aerospace for the aviation and aerospace industries and their suppliers. In this standard, not only the quality of the furnace – similar to DIN 17052 – is specified in terms of uniformity but also the regular inspection of these by so-called SAT and TUS measurements. It stipulates in different furnace classes how precise the temperature uniformity in the unloaded usable space must be during the steady state and how this must be determined, as well as the exact structure and accuracy of the measurement chain and the periodic repetition of the measurements.
This means that the empty furnace is heated to its working temperature and then uniformity is measured and documented at several points in the furnace (different numbers depending on the size).
AMS 2750 specifies the position and quality of the sensors or the entire measurement chain, as well as a specification of the maximum deviation.
Example: A furnace of furnace class 3 must achieve a uniformity of +/-8K; a furnace of furnace class 1 must achieve +/-3K.
As Airtec furnaces achieve a uniformity of +/-5K as standard, you are always safe when working with our products in the areas of furnace class 2. If you need furnace class 1, we are happy to design your furnace accordingly so that you can fulfil any audit.
Airtec Thermoprocess GmbH
Heinrich-Hertz-Str. 2
DE-46414 Rhede
