We use a conveyor furnace for our heat treatment processes. A vibratory conveyor ensures that the parts are spread out evenly on the belt on which they travel into the inert gas tunnel furnace. Inside the furnace, and protected by a special inert gas, they are heated to a temperature of up to 900°C after which they are quenched in an oil bath to around 70°C. They then arrive at the washing unit, where first of all the oil is removed by centrifugal action. At a second station we wash the fasteners with water and detergent.
In a third and final step they are dried. Now the clean and dry parts move on to the tempering furnace where they obtain the required hardness, toughness and strength characteristics. Tempering temperatures are generally between 340° and 620°C. For improved handling we then cool the fasteners down to room temperature inside an emulsion bath. Finally, the hardened and tempered items are dried and then moved on for a number of different checking operations.