Search Results for roll forging

Roll forging is a process for simultaneously reducing the cross-sectional area and changing the shape of heated bars, billets, or plates. This article provides an overview of the process capabilities, production techniques, machines and machine size selection considerations, and types of roll dies and auxiliary tools for the roll forging. It concludes with information on the production examples of roll forging.

Forging machines use a wide variety of hammers, presses, and dies to produce products with the desired shape, size, and geometry. This article discusses the major types of hammers (gravity-drop, power-drop, high speed, and open-die forging), and presses (mechanical, hydraulic, screw-type, and multiple-ram). It further discusses the technologies used in the design of dies, terminology, and materials selection for dies for the most common hot-forging processes, particularly those using vertical presses, hammers, and horizontal forging machines. A brief section is included on computer-aided design in the forging industry. Additionally, the article reviews specific characteristics, process limitations, advantages, and disadvantages of the most common forging processes, namely hot upset forging, roll forging, radial forging, rotary forging, isothermal and hot-die forging, precision forging, and cold forging.

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.

Control of grain flow is one of the major advantages of shaping metal parts by rolling, forging, or extrusion. This article shows the effects of anisotropy on mechanical properties. Cylindrical forgings commonly have a straight parting line located in a diametral plane. The alternate classes of parting lines are called either "straight" or "broken" for brevity. Regardless of whether draft is applied or natural, the forging will have its maximum spread or girth at the parting line. Proper placement of the parting line ensures that the principal grain flow direction within the forging will be parallel to the principal direction of service loading. The article reviews the mutual dependence of parting line and forging process. It provides a checklist for the forging designer that suggests a systematic approach for establishing parting line location. Finally, the article contains examples, with illustrations of parting line locations, accompanied by tables of design parameters.

This article discusses the properties of threaded fasteners made from carbon and low-alloy steels containing a maximum of 0.55% carbon. It provides guidelines for the selection of steels for bolts, studs, and nuts intended for use at temperatures between -50 and 370 deg C. The article also discusses steels rated for service above 370 deg C and describes internationally recognized grade designations. The specifications provided can be used to outline fastener requirements, control manufacturing processes, and establish functional or performance standards. The most commonly used protective metal coatings for ferrous metal fasteners; zinc, cadmium, and aluminum; are described as well.