This article provides an overview of the capabilities of closed-die forging. One of the most important aspects of closed-die forging is proper design of preforming operations and of blocker dies to achieve adequate metal distribution. The article describes the effects of friction and lubrication in forging. It discusses the types of closed-die forgings, namely, blocker-type, conventional, and close-tolerance. The article illustrates the classification of forging shapes and explains how to predict the forging pressure and the control of die temperature during closed-die forging. It explains the use of heating equipment for closed-die forging and tabulates the maximum safe forging temperatures for carbon and alloy steels. The article concludes with a discussion on a trimming method used for closed-die forgings.

Forgings are classified in various ways, beginning with the general classifications open die and closed die. They are also classified according to how they are made; such as hammer upset forgings, ring-rolled forgings, and multiple-ram press forgings; and in terms of the close-to-finish factor or amount of stock that must be removed to satisfy the dimensional and detail requirements of the finished part. In addition to types and classifications, the article discusses critical design factors and ways to ensure that the resulting forgings measure up to metallurgical, mechanical property, and dimensional accuracy requirements. The responsibility for design verification is vested in material control, which depends on the proper application of drawings, specifications, manufacturing process controls, and quality assurance programs. The article addresses each of these areas as well as related topics; including stress-induced fatigue failure, tolerances, machining allowances; and the fundamentals of hammer and press forgings, hot upset forgings, and hot extrusion forgings.

Forging is the process of working hot metal between dies, usually under successive blows and sometimes by continuous squeezing. This article describes the material selection criteria, quality assurance tests for forged components, and the dimensional tolerances of closed-die steel forgings. It provides an overview of the mechanical properties of wrought materials. The article also includes information on the fundamentals of hammer and press forgings and the design of hot upset forgings.