The process of automatic hot forging involves putting in mill-length steel bars into one end of the machine and having hot forged products emerge from the other end. The high output rate and ability to accept low-cost materials and minimal labour requirements for operating the machinery are the main advantages of this process.
As compared to conventional forging units in India, automatic hot forging has material savings between 20% - 30%. The tolerance of this process is usually + - 0.3 mm (0.012 in), with clean surfaces and draft angles at 0.5 to 1 degree. Contact times in automatic hot forging are on the order of 0.06-seconds, thereby increasing the tool life in this process. One disadvantage of this process however, is that it is only feasible for smaller symmetric parts.
In this process, the bars are heated by the high power induction coils and then descaled by rollers. The rods are sheared into blanks and then transferred through several successive forming stages. High-speed cold-forming operations can also be coupled with this process. The cold forming operation can take care of the finishing stages. This way the advantages of cold-working can be obtained and the high speed of automatic hot forging can also be maintained.
Neck rings for LPG gas cylinders, stainless steel coupling flanges, tapered roller bearing races, transmission gears, and wheel hub unit bearings are a few parts that are made at automatic hot forging units in India, while manual transmission gears are examples of automatic hot forging used in conjunction with cold working.