TECNA S.p.A., a company situated in Castel S. Pietro Terme (BO) - ITALY, has been working in the field of resistance welding since the beginning of the‘70s. During these years it has become a well-known company specialized in the production of a vast range of spot and projection welding machines briefly listed hereafter: spot and projection bench welding machines 16-150 kVA single-phase linear action welding machines 35-315 kVA D.C. three-phase linear action welding machines 100-630 kVA automatic air operated suspended guns with built-in transformer 16-75 kVA production spot guns medium frequency 56-140 kVA, from 16 to 45 kA rocker-arm pedestal spot welders 12-50 kVA modular spot welders: twin spot, rocker arm, linear action spot welders for car body repair, portable and self-contained, hand and air operated, single and three-phase versions D.C., 2-20 kVA powers. Moreover, TECNA manufactures a line of products which can be considered “accessories” to the resistance welding machines: adaptive and digital welding control units, with microprocessor, ammeter, constant current and standard versions test and measurement instruments for resistance welding machines balancers from 0,4 to 180 kg.