Portable Spot Welding Guns
MFDC Control Unit TE 700 is the control unit to control and manage the MFDC Inverter Booster, which in turns supplies the high frequency power to the welding transformer.
TECNA's medium frequency system works with different frequencies (up to 4kHz) and with six different working modes.
FIX (Partialisation percentage of the delivered power) - This mode is suitable either to short welding processes with big resistance variations or to material heating.
IK (Constant Current) - Constant current welding mode, that facilitates to keep the welding current same, even when the mains voltage, impedance of the secondary circuit, conditions of the welding tools and in the superficial conditions of the material to be welded, keep on changing.
PWK (Constant Power) - This mode is suitable for compensation of the material wear or suitable for materials that change their resistance during the welding significantly. In fact, the system compensates the initial phase of the melting process with a reduction of the current as a function of the resistance. This avoids indentations and expulsion of molten material which would obviously affect the quality of the spot.
ENE (Constant Energy) - This mode is suitable when one needs to apply always the same energy (heat) to the material to be welded, to avoid splashes of molten material and to increase the life of the electrodes.
VEK (Constant voltage) - It keeps constant the secondary voltage during the welding. This mode is useful for special applications for certain materials, where particular electrodes, such as Tungsten are used.
DYNAMIC MODE - This mode is also called ADAPTIVE. In fact, it is able to detect possible abnormal conditions like impurities on sheets, incorrect overlapping, electrodes wear etc., and to dynamically change and compensate parameters during the welding process and try achieving always the same final welding results. This "real time" compensation is carried out by extending or shortening the welding time up to a maximum limit set by the operator. The control unit also compensates the welding current, in this case for avoiding the projection and the expulsion of molten material.
The welding process can be kept under control by using different windows of LIMITS which could be: Current, Voltage to the electrodes, Energy, Power and in FIX. Moreover, it is possible to control the current supply through an analogue signal in voltage of 0-1 0 V (External Input) and to generate a current profile proportional to the voltage signal.
CONCLUSIONS - The medium frequency system allows gaining different advantages, which can be summarized as follows:
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