Forging Notes
CHAPTER 2
Forging Processes: Variables and Descriptions
Manas Shirgaokar
2.1
Introduction
In forging, an initially simple part—a billet, for example—is plastically deformed between two tools (or dies) to obtain the desired final configuration. Thus, a simple part geometry is transformed into a complex one, whereby the tools “store” the desired geometry and impart pressure on the deforming material through the tool/material interface. Forging processes usually produce little or no scrap and generate the final part geometry in a very short time, usually in one or a few strokes of a press or hammer. As a result, forging offers potential savings in energy and material, especially in medium and large production quantities, where tool costs can be easily amortized. In addition, for a given weight, parts produced by forging exhibit better mechanical and metallurgical properties and reliability than do those manufactured by casting or machining. Forging is an experience-oriented technology. Throughout the years, a great deal of know-how and experience has been accumulated in this field, largely by trial-and-error methods. Nevertheless, the forging industry has been capable of supplying products that are sophisticated and manufactured to very rigid standards from newly developed, difficult-to-form alloys. The physical phenomena describing a forging operation are difficult to express with quantitative relationships. The metal flow, the friction at the tool/material interface, the heat generation and transfer during plastic flow, and the relationships between microstructure/properties and
process conditions are difficult to predict and analyze. Often in producing discrete parts, several forging operations (preforming) are required to transform the initial “simple” geometry into a “complex” geometry, without causing material failure or degrading material properties. Consequently, the most significant objective of any method of analysis is to assist the forging engineer
Forging Processes: Variables and Descriptions
Manas Shirgaokar
2.1
Introduction
In forging, an initially simple part—a billet, for example—is plastically deformed between two tools (or dies) to obtain the desired final configuration. Thus, a simple part geometry is transformed into a complex one, whereby the tools “store” the desired geometry and impart pressure on the deforming material through the tool/material interface. Forging processes usually produce little or no scrap and generate the final part geometry in a very short time, usually in one or a few strokes of a press or hammer. As a result, forging offers potential savings in energy and material, especially in medium and large production quantities, where tool costs can be easily amortized. In addition, for a given weight, parts produced by forging exhibit better mechanical and metallurgical properties and reliability than do those manufactured by casting or machining. Forging is an experience-oriented technology. Throughout the years, a great deal of know-how and experience has been accumulated in this field, largely by trial-and-error methods. Nevertheless, the forging industry has been capable of supplying products that are sophisticated and manufactured to very rigid standards from newly developed, difficult-to-form alloys. The physical phenomena describing a forging operation are difficult to express with quantitative relationships. The metal flow, the friction at the tool/material interface, the heat generation and transfer during plastic flow, and the relationships between microstructure/properties and
process conditions are difficult to predict and analyze. Often in producing discrete parts, several forging operations (preforming) are required to transform the initial “simple” geometry into a “complex” geometry, without causing material failure or degrading material properties. Consequently, the most significant objective of any method of analysis is to assist the forging engineer
References: [Altan, 2002]: Altan T., “The Greenfield Coalition Modules,” Engineering Research Cen- Forging Processes: Variables and Descriptions / 15