How Are Forgings Produced?
Forging--metal shaping by plastic deformation--spans a myriad of equipment and techniques. Knowing the various forging operations and the characteristic metal flow each produces is key to understanding forging design.
Hammer and Press ForgingThe processes
Generally, forged components are shaped either by a hammer or press. Forging on the hammer is carried out in a succession of die impressions using repeated blows. The quality of the forging, and the economy and productivity of the hammer process depend upon the tooling and the skill of the operator. The advent of programmable hammers has resulted on less operator dependency and improved process consistency. In a press, the stock is usually hit only once in each die impression, and the design of each impression becomes more important while operator skill is less critical.
The Precision Forging Advantage
Precision forging normally means close-to-final form or close-tolerance forging. It is not a special technology, but a refinement of existing techniques to a point where the forged part can be used
with little or no subsequent machining. Improvements cover not only the forging method itself but also preheating, descaling, lubrication, and temperature control practices.
The decision to apply precision forging techniques depends on the relative economics of additional operations and tooling vs. elimination of machining. Because of higher tooling and development costs, precision forging is usually limited to extremely high-quality applications.