This chapter discusses the use of finite-element methods for modeling cold forging processes. The discussion covers process modeling inputs, such as geometric parameters, material properties, and interface conditions, and includes several application examples.

This chapter discusses the process of cold forging and its effect on various materials. It describes billet preparation and lubrication procedures, cold upsetting techniques, and the use of slab analysis for estimating cold forging loads. It likewise describes extrusion processes, explaining how to estimate friction and flow stress and predict extrusion loads and energy requirements. The chapter also discusses the tooling used in cold forging, the parameters affecting tool life, and the relative advantages of warm forging.

This chapter addresses the issue of die failures in hot and cold forging operations. It describes failure classifications, fatigue fracture and wear mechanisms, analytical wear models, and the various factors that limit die life. It also includes several case studies in which finite-element modeling is used to predict die failure and extend die life.

This chapter discusses the design and operation of forging presses and hammers. It covers the most common types of presses, including hydraulic, mechanical, and screw presses, explaining how they work and comparing and contrasting their load and displacement profiles, stroke lengths, ram velocities, and energy and stiffness requirements. It also includes information on gravity- and power-drop hammers and where and how they are typically used.

This article presents six case studies of failures with steel forgings. The case studies covered are crankshaft underfill; tube bending; spade bit; trim tear; upset forging; and avoidance of flow through, lap, and crack. The case studies illustrate difficulties encountered in either cold forging or hot forging in terms of preforge factors and/or discontinuities generated by the forging process. Supporting topics that are discussed in the case studies include validity checks for buster and blocker design, lubrication and wear, mechanical surface phenomenon, forging process design, and forging tolerances. Wear, plastic deformation processes, and laws of friction are introduced as a group of subjects that have been considered in the case studies.

This chapter discusses bulk deformation processes and how they are used to reshape metals and refine solidification structures. It begins by describing the differences between hot and cold working along with their respective advantages. It then discusses various forging methods, including open-die and closed-die forging, hot upset and roll forging, high-energy-rate forging, ring rolling, rotary swaging, radial and orbital forging, isothermal and hot-die forging, precision forging, and cold forging. The chapter also includes information on cold and hot extrusion and drawing operations.

This chapter discusses the factors that affect die steel selection for hot forging, including material properties such as hardenability, heat and wear resistance, toughness, and resistance to plastic deformation and mechanical fatigue. It then describes the relative merits of various materials and the basic requirements for cold forging dies. The chapter also covers die manufacturing processes, such as high-speed and hard machining, electrodischarge machining, and hobbing, and the use of surface treatments.

This chapter discusses the effect of friction and lubrication on forgings and forging operations. The discussion covers lubrication mechanisms, the use of friction laws, tooling and process parameters, and the lubrication requirements of specific materials and forging processes. The chapter also describes several test methods for evaluating lubricants and explains how to interpret associated test data.

This chapter defines near-net shape forging as the process of forging parts close to their final dimensions such that little machining or only grinding is required as a final step. It then describes the causes of dimensional variations in forging, including die deflection, press deflection, and process inconsistencies, and discusses related innovations.