Abstract: The heating system of cork drum in YJ29 assembler existed some problems,such as not convenient to threading the hot wires,ill-contact,short armature life,not convenient to check and maintenance.The cork drum was improved as following:the body of cork drum was made of magnet-conductive martensitic steel and heated by a stationary electromagnetic coil free of contact with the cork drum instead of the electric heater;the shaft of cork drum was machined rather than casted;power line was connected to the coil and the armature was removed.The improvement simplified the cork drum,shortened its heating time,and increased its running reliability.