In the case of thermal impulse welding, the welding heat is created in a thin metallic heater band by means of electrical impulses (resistance heating). The heater band is made from a special alloy and can come in the form either of a straight heater band with a welding width of 3 to 45 mm, or as a contoured heater band as required. The welding temperature for this process can be precision regulated. Owing to the low mass of the heater band, it can be heated (to 20 to 200°C in approx. 0.5 seconds) and cooled quickly. The option of further cooling under pressure ensures that the quality of the seam is very high.