Abstract: The invention provides an apparatus and method for controlling a heat bonding process in a heat bonding apparatus. The temperature is sensed at an interface between the pressing means and the article to be pressed and a signal processing means detects a rapid change in temperature at the interface to provide a start-of-cycle signal indicating initiation of the heat bonding cycle. The signal processing means then detects the attainment of pre-set temperature reached at the interface to provide an end-of-cycle signal signifying the completion of the heat bonding cycle. The heat bonding apparatus may comprise a heat seal press, a heat fusion machine, apparatus for transfer printing and fusion, apparatus for hot melt printing, thermal fixing apparatus, apparatus for the lamination of, for example, two substrates via hot melt adhesives in which the substrates are held in position by means of clamps or frames, and moulds for the curing of materials, such as, for example, rubber.