In the manufacture of castings, the molten metal’s temperature is still often measured manually with immersion thermometer. For measuring, the immersion probe is dipped into the melt. A new element is necessary for each measurement. Because of costs of about 1 euro per element, the mere running costs arise up to several thousand euros a year. The costs for the operating personnel aren’t taken into account so far.
With modern infrared thermometers, the operator is nowadays able to measure the infrared radiation and thus the temperature of the molten metal from distance. The especially for measuring of molten metals developed devices are able to detect the correct temperature of slag and oxide free surfaces within seconds, due to an analytical filter function. The two-colour or dual wavelength measuring method ensures stable and accurate temperature readings, despite of dust and smoke in the field of view. The rectangular measuring area of the pyrometer also plays part in contributing a reliable measurement, even in case of a fluctuating pouring stream.
The devices are used at runner of blast and cupola furnace, when pouring into the ladle and especially when pouring the melting into the moulds. Particularly this measuring location is decisive for the process and enables the control and documentation of the compliance with the allowed pouring temperature for each produced casting.
Because the temperature is measured in the furnace or ladle far before it is filled by using immersion probes, a proof of compliance with the necessary pouring temperature cannot be provided. Especially complex components have a clearly higher scrap rate than 10%. Thanks to the measure with the pyrometer, the scrap rate can be reduced to far below 3 %. The thereof resulting cost savings amount to several thousand euros a month, depending on the output quantity.
Fixed measuring systems with connection to the central data acquisition, as well as mobile devices for quick checks in between, are available on the market. Infrared thermometers are wear-free, maintenance-free and extremely long-lasting. Investment costs between 3,500 and 6,000 euros are therefore amortized in the shortest possible time.