Our heavy duty four roll machine is a symmetrical roll design. The material is entered into the pinch point between the top and lower pinch roll. The entry side form roll is then placed into position for pre-forming the leading edge of the part. The part is then fed into the machine forming the leading edge. After the leading edge if formed the entry side form roll is lowered and the exit side form roll is placed into position to finish forming the part. The total process is one entry one pass forming.