A continuous furnace is the type mostly used for in-line large quantity production. It typically has a horizontal work chamber and a mechanical means of conveying the work from one end to the other. Heating may be electrical or done by burning fuel. Many furnaces have different temperatures precisely controlled in several zones for multistage heat-treating.

Some authorities call only those furnaces continuous in which the workpieces all move at the same rate from one end to the other. The name of cycling or semicontinuous furnace is given when the work is held for a different present time in each section of the furnaces. In either case, small pieces may be carried through in baskets or on trays.