DN grease is primarily used for lubrication between the shaft and the electricity feeding shoe of the rotating electrode head in seam welding machines. Since the rotating electrode head is a mechanism that bears heavy stress in supplying a large current and transferring applied pressure while rotating, lubrication is very important. DN grease, whose state is that of a consistent paste, works as a solid lubricant when the head temperature is low to prevent wearing of the contact surfaces that feed electricity. DN grease works as lubricating oil when the temperature at the electricity feeding point reaches the dropping point. Another advantage of DN grease is that it does not corrode the metal of the head. In light of these factors, DN grease is the most suitable grease for maintaining the functions of the rotating electrode head.