The controls found on HF25 series closed loop welders address the challenges of microjoining. Miniature welds are highly sensitive to small heat profile fluctuations in the resistance welding process. Overheating deforms and destroys parts, while under heating results in a weak, unacceptable bond. To achieve consistent, reliable welds of small to microminiature parts, precisely controlled heating is required. This necessitates superior control of the energy output.