Pit type nitriding furnace is standard energy-saving cycle operation nitriding resistance furnace .Mainly used for nitriding treatment under the medium conditions of ammonia and methanol for all kinds of steel mechanical parts,automobile crankshaft, piston rod, mold , auto slender rods , and can also be used as general pit type heat furnace without any medium in the air .The nitrogen should be firstly supplied into the furnace to exhaust the air in the furnace before heating up the furnace,the nitrogen volume for exhausting air should be at least twice than normal operation .After several minutes's exhausting ,please continue heating to exhaust air, after two hours ,constant pressure nitriding for several hours,after completion of the nitriding process ,denitrogen for 1 to 2 hours , when the temperature has dropped below 150 degrees Celsius ,then nitrogen supply can be stopped and the workpiece can be drawn out of the furnace.