This article begins with a discussion on the factors considered in the selection of bending methods. It presents a detailed description of the types of bending method, machines and tools used in the bending and forming of tubing. The article provides an overview of bending tubing with and without a mandrel and hot bending. It concludes with a discussion on the bending of thin-wall tubes and lubrication for tube bending.

Bending is a common metalworking operation to create localized deformation in sheets (or blanks), plates, sections, tubes, and wires. This article emphasizes on the bending of sheet metal along with some coverage on flanging. It informs that variations in the bending stresses cause springback after bending, and discusses the variables and their effects on springback, as well as the methods to overcome or counteract them. These methods include overbending, bottoming or setting, and stretch bending. The article provides information on elastic bending, non-cylindrical bending, elastic-plastic bending, and pure plastic bending. Sheet metal bendability is a critical factor in many forming operations. The article illustrates the derivation of two relevant bend-ductility equations.

This article describes various bending methods: draw bending, compression bending, roll bending, stretch bending, and ram-and-press bending. It discusses the machines used for the bending of bars. These machines include devices and fixtures for manual bending, press brakes, conventional mechanical and hydraulic presses, horizontal bending machines, rotary benders, and bending presses. The article illustrates the tools used in bending and other bending process. It also tabulates the lubricants required for bending specific metals.

A characteristic feature of bending is the inhomogeneous (nonuniform) nature of the deformation. Therefore, in a bent specimen, the strain and stress at a given point are dependent on the location of the point with respect to the neutral axis of the cross-sectional area of the specimen. This article discusses the stress-strain relationships, strain curvature, and stress-moment equations for elastic, noncylindrical, elastic-plastic, and pure plastic bending conditions. It also reviews the distribution of residual stress and springback.

Bending fatigue of carburized steel components is a result of cyclic mechanical loading. This article reviews the alloying and processing factors that influence the microstructures and bending fatigue performance of carburized steels. These include austenitic grain size, surface oxidation, retained austenite, subzero cooling, residual stresses, and shot peening. The article describes the analysis of bending fatigue behavior of the steels based on S-N curves that represents a stress-based approach to fatigue. It discusses the types of specimen used to evaluate bending fatigue in carburized steels. The stages of fatigue and fracture of the steels, namely crack initiation, stable crack propagation, and unstable crack propagation, are reviewed. The article analyzes the intergranular fracture at the prior-austenite grain boundaries of high-carbon case microstructures that dominates bending fatigue crack initiation and unstable crack propagation of direct-quenched carburized steels.

Bend tests are conducted to determine the ductility or strength of a material. This article discusses the different bend tests with emphasis on test methods, apparatuses, procedures, specimen preparation, and interpretation and reporting of results. The types of bend tests discussed are bending ductility tests, bending strength tests (ASTM E 855), bend tests as per EN 12384 and JIS 3130, and computer-aided bending tests. The three standard bending strength tests are the cantilever beam bend test, the three-point bend test, and the four-point bend test. European Standard EN 12384 specifies a bend test to determine the modulus of elasticity in bending. Japanese Industrial Standard JIS 3130 specifies two tests to determine the elastic limit of spring plate or strip: the repeated deflection spring test and the moment type spring test.