INFEED OR PLUNGE TYPE Dies must be wider than the thread length being rolled as infeed rolling dies have full helix angle ground into them, and there is very little part movement. THRUFEED ROLLING ANNULAR RING DIES Annular rings are ground on dies with no helix angle.  The spindles on the machine are tilted to the same helix angle as the work causing the part to feed through the machine.  Annular ring dies can only be used were the helix angle does not exceed the spindle tilt. COMBINATION DIES (HELICAL SLOW FEED) For rolling long threads with high helix angles, part of the helix angle is ground into the dies and the rest of the helix angle is tilted on the machine's spindles. (Combination dies use less power and rolling pressure than annular ring dies.) SPEED-UP DIES (HELICAL FAST FEED) For rolling long threads, bars feed through the machine 1-1/2 to 3 times faster than annular ring dies at the same RPM. THREAD FORMS Most thread forms can be rolled.  Standard "V", ACME, Butress, Worms, Balls, ect. SPECIAL FORMS Knurling, straight and diamond, grooving, annular rings or helical such as oil grooves.  Burnishing for smooth finish and increased strength.