Search Results for die hardness

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 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 extrusion technology of hard alloys. The chapter provides an overview of hollow extrusion for aerospace application. It presents extrusion defects related to hard alloys. The chapter describes the extrusion quality requirements for aerospace applications. It also discusses extrusion of aluminum-matrix composites. The chapter outlines the powder metallurgy process for making billets for extrusion.

This chapter discusses many aspects of extrusion die and tooling, including the terminology and function of extrusion die and tooling, the types of dies, the fundamentals of die design, manufacturing, correction, material, and the surface treatments of die bearings and tribology in extrusion dies. It then presents the fundamentals and function of finite-element modeling simulation. The chapter describes the role of tribology and thermodynamics in the die bearing to control the flow and dimensional stability of extrusion exiting the die.

The nitriding process can be applied to various materials and part geometries. This chapter focuses on tool steels, pure irons, low-alloy steels, and maraging steels. Various considerations such as the surface metallurgy requirements of the die, including case depth, compound layer formation, and temperature, are also discussed in this chapter. The chapter also addresses steel selection and surface metallurgy of gears.

This chapter covers the different types of wear encountered in metalworking processes. It discusses the mechanisms involved in adhesive, abrasive, chemical, and fatigue wear and key contributing factors, including the composition and structure of tool and workpiece materials, the characteristics of contact surfaces, and loading forces imposed by the process. It describes the nature of metal transfer between tool and workpiece surfaces and the role of lubricants, coatings, and textures. It also discusses the use of wear maps, the effects of adhesion, and material-lubricant interactions.

In this chapter, process control of each operational stage is discussed, with a detailed process-control flow diagram to provide a better understanding and to create a process-control document of each operational process stage. This chapter also presents fundamental ideas of a complete process- and quality-control framework system of an aluminum extrusion plant, starting from alloy and billet making to the final heat treatment process parameters required to bring the extrusion to the final alloy and temper designation to meet product requirements.

Steels for hot-work applications, designated as group H steels in the AISI classification system, have the capacity to resist softening during long or repeated exposures to high temperatures needed to hot work or die cast other materials. These steels are subdivided into three classes according to the alloying approach: chromium hot-work steels, tungsten hot-work steels, and molybdenum hot-work steels. This chapter discusses the composition, characteristics, applications, advantages, and disadvantages of each of these steels.

The several specific grades or compositions of tool steels have evolved over time and have been organized into useful groupings. This chapter presents the AISI classification system for tool steels, which categorizes tool steels by their alloying, applications, or heat treatment, and briefly describes the characteristics of each major group. It discusses selection criteria for tool steels, along with examples.

This chapter focuses on the failure aspects of tool steels. The discussion covers the classification, chemical composition, main characteristics, and several failures of tool steels and their relation to heat treatment. The tool steels covered are hot work, cold work, plastic mold, and high-speed tool steels.

This data set contains approximately 50 growth curves for a wide range of aluminum casting alloys at various temperatures. Growth curves are used to determine the dimensional changes that must be anticipated during service in applications where close dimensional tolerances are required. Hardness curves are provided for many of the alloys. The hardness values are from corresponding aging response studies in which measurements were made on individual lots considered representative of the respective alloys and tempers.

Mold steels are used for plastic molding and certain die-casting applications and are designated as group P steels in the AISI classification system. The fabrication and performance requirements that differentiate them from other types of tool steels are described in this chapter. It provides information on hubbing and machined cavity grades of mold steels and describes the performance of the corrosion-resistant mold steels. The chapter discusses the processes involved in forging, annealing, stress relieving, carburizing, hardening, and tempering of mold steels. It presents the selection criteria and applications of mold steels.

This chapter discusses the scope of research and development in aluminum extrusion technology. Research in the key technology areas of friction, thermodynamics, and die wear are discussed. The chapter also highlights future developments in extrusion technology.

This chapter familiarizes readers with the design, configuration, and function of tooling and dies used to extrude aluminum alloys. It discuses basic design considerations, including the geometry, location, and orientation of die openings; allowances for thermal shrinkage, stretching, and deflection; and the length and profile of bearing surfaces. It outlines the steps and processes involved in die making, describes the selection and treatment of die materials, and examines the factors that influence friction and wear. It also discusses the general procedures for on-site die correction.