Manufacturers of products are not only interested in low-cost production, but above all in a consistently high quality of their products. This includes, of course, and in particular, reproducible heat treatment at a high level and this is primarily dependent on whether the products are always heated up at the same rate 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 working chamber and this is precisely specified in DIN 17052-1, CQI-9 and AMS 2750.
The DIN 17052-1 standard specifies in several quality classes how precise the temperature uniformity in the unloaded working chamber 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 (depending on the size of the product) or that a representative product is fitted with several sensors and then heated to the working temperature.
The standard specifies the position and 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 tempering unalloyed steels should have quality class C and thus 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 meet this value as standard. This means that we lie exactly between quality class A and B in the standard and thus offer the best compromise between price and performance – however, we can of course also deliver according to quality class A or even better at the customer’s request.