Thermocouples and Samplers
The constant progress of technique and production technologies requires the continuous improvement of the characteristics of metallic materials, subject to increasingly demanding conditions of use.
To satisfy this requirement, materials, and castings made with them must be subjected to improved control methods. In the past, the foundry industry has mainly concentrated its efforts only on production operating systems, especially on design, structures, and procedures. Nowadays, it is imperative that process control is addressed in its entirety, and that all functions that influence it are controlled.
The temperature control of the liquid metal plays a role of fundamental importance in modern foundries, as does the control of the analytical composition and the solidification methods by means of thermal analysis. For this reason, Proservice supplies a series of type-S thermocouples ITACA Temp with high efficiency, Made in Italy, with lengths from 300 to 1200 mm, with and without anti-splash. Furthermore, some types of products available are part of the so-called “multi dip” class, i.e., with them it is possible to carry out multiple temperature measurements with the same thermocouple, thus offering the possibility of saving on costs and further protecting the environment thanks to less use of material.
Proservice also supplies a series of anti-splash thermocouples. This solution allows to obtain a series of undoubted advantages. First of all, the absence of splash generation when the thermocouple is immersed, which consequently imply an increase in operator safety. Furthermore, the anti-splash thermocouples allow you to make more measurements and therefore reduce operating costs.
OUR EQUIPMENT, OUR SOLUTION: ITACA DPS
Proservice also supplies the ITACA DPS temperature portable measurer, very robust and very reliable, with Wi-Fi transmission of temperature data. The measurement can also be read in a clearly visible display at considerable distances. To acquire the temperature, ITACA Temp thermocouples are used which, together with the specially designed electronic circuit, guarantee high precision and reliability of the measurement.
Proservice can also carry out instrument calibration, a free service for our customers.
THE KEY-ROLE OF OUR RESEARCH AND DEVELOPMENT
The high experience gained in the cast iron foundries that use ITACA thermal analysis, has offered us the possibility to test our thermocouples and measurer directly in the field and to compare them with those available on the market, thus being able to search for the best possible solution, in terms of geometries and materials, to obtain the temperature value quickly and with very high precision and repeatability.
THE TEMPERATURE OF THE MELT CAST IRON
As mentioned before, the temperature of the melted cast iron is one of the most important process parameters. In fact, the temperature at which the metal is melted, maintained, treated, and cast heavily affects the quality of the castings and it is considered a key variable of the entire melting and casting process. It must therefore be carefully monitored with a view to producing defect-free castings.
The choice of casting temperature normally considers aspects concerning the geometry and dimensions of the casting and must be chosen in such a way that the root cavity is filled during the pouring phase and solidifies in the absence of defects.
In fact, pouring temperatures that are too low lead to defects such as incomplete casting and cold joints or misruns, but also to macro-porosity from shrinkage, gas entrapment, and slag inclusions, while pouring temperatures that are too high could lead to micro-porosity.
The temperature also has an impact on its interaction with the molding sand. Too-high temperatures could lead to defects such as sintering, surface roughness, and penetrations due to chemical reactions and scrubbing, while too-low temperatures could lead to lustrous carbon inclusions and pinholes.
The temperature also strongly influences the metallurgy of the cast iron and particularly the shape and distribution of the graphite particles, both in the case of lamellar and nodular cast iron. In the specific case of nodular cast irons, the higher the temperature of the metal, the higher the rate of fading of the magnesium.
Therefore, if a high pouring temperature is required, it is necessary to provide an overdose of spheroidizing alloy to compensate for the greater losses of magnesium and this can obviously lead to a greater risk of non-compliant spheroidizing. Furthermore, the high temperature of the metal affects not only the spheroidisation treatment, but also the inoculation process and the nucleation potential: if the molten metal is preserved for a prolonged period at a high temperature, the inoculants fading is more facilitated, and graphite defects could occur such as malformed spheroids, but also exploded graphite, chunky graphite and, in the worst cases, the appearance of cementite or carbides.