Seam Welding
Questions and Answers
One of the frequent uses of seam welders is for metal barrels or cylinders. Barrels are used in all sizes and are seam welded on longitudinal welders. Here the part runs into the throat of the machine and then is reversed and run back out. The seams are fluid tight and are used in many industries. Most barrels are roll formed to install a gusset for strength after welding. This gusset will be the lip which holds the top and bottom end pieces. The seam weld will maintain its integrity even after these forming operations.
There sometimes are clearance issues that demand that the two seam welding wheels cannot operate on the same axis. One or both might have to be leaned a little for part clearance. This can be done.
Seam welding can involve large amount of power especially in a continuous seam weld. This generates a lot of heat which must be removed. The weld wheels are cooled through the hub that attaches them to the machine. Unfortunately this can be a long distance from the actual weld face. Just as in spot welding we need cooling near the face to help maintain the wheel integrity. In higher heat applications external water may be required. Water tubes are installed on both sides of the wheel top and bottom and cool water is spray on the wheel and weld area. This of course can be very messy but necessary for some applications.
Seam welds are a series of spot welds in a straight line. They can be overlapping or separated. Overlapped welds are used in fluid tight application and spaced welds in normal structural weld situations. A washing machine drum would be a water tight application. If the welds are separated the process is sometimes referred to as roll spot welding.
Seam welding will generally use the same alloys as spot welding. The higher conductivity lower strength workpieces will be welded using Class 2 and the stronger work pieces will use Class 3. As in the case of spot RWMA Class 2 is the most used product for seam welding. Most seam welding wheels are ideally cross forged to break up the original cast billet grain structure. There are two schools of thought on this forging. One is to forge blanks after being sliced from a cast billet. The other is to forge the cast billet then slice the blank. Both processes break up cast structure but to different degrees. The individual forged blank process will inherently cost more since you forge each blank individually. If you have a difficult heavy wheel wear application you might want to consider paying the extra dollars.
Some wheels are made by cutting ends off rod and others by cutting out of plate. Neither of these products would be expected to hold up in heavy duty applications.
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