Production Engineering Technology

Frontmatter

1. Introduction

Abstract

The shaping of materials before they are incorporated into a product usually occurs in a number of stages. Specific examples of the shaping processes used to produce five different parts are illustrated in Fig. 1.1 (a) and an outline of the main groups of shaping processes is shown in Fig. 1.1 (b). It will be seen that some parts which have been cast, sintered or moulded can be incorporated directly into assemblies without further processes, although usually machining is required. Primary forming operations produce a range of products such as forgings, bar, plate and strip, which is either machined or further formed in the factory. Some factory formed parts, however, still have to be machined before they are assembled.

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J. D. Radford, D. B. Richardson

2. Manufacturing Properties of Metals

Abstract

Methods of plastic deformation are used extensively to force metal into a required shape. The processes used are diverse in scale, varying from forging and rolling of ingots weighing several tons to drawing of wire less than 0·025 mm (0·001 in) in diameter. Most large-scale deformation processes are performed hot, so that a minimum of force is needed and the consequent recrystallization refines the metallic structure. Cold working is used when smooth surface finish and high dimensional accuracy are required. Although a growing number of components is manufactured completely from a series of deformation processes, metal forming is primarily used to produce such material as bar and sheet which is subsequently machined or pressed into its final shape. A chart showing the major metal-forming processes can be seen in Fig. 2.1.

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J. D. Radford, D. B. Richardson

3. Basic Plasticity

Abstract

It is intended that this chapter should indicate how metal behaves when plastically deformed and so provide a quantitative basis for dealing with metal cutting and forming in the rest of the book. A rigorous mathematical treatment would be inappropriate and space does not permit a complete discussion of this interesting subject. Those seeking a more comprehensive treatment are referred to the bibliography.

J. D. Radford, D. B. Richardson

4. Hot Forging and Rolling

Abstract

Forging is made up of a diverse group of hot and cold shaping processes and produces parts varying in weight from several tons to a few ounces. In this chapter hot forging has been grouped with hot and cold rolling, as both can be considered primary forming operations which are largely confined to the forge or steelworks. Cold forging is normally a factory forming operation and in consequence has been included with other factory forming processes in Chapter 6.

J. D. Radford, D. B. Richardson

5. Extrusion, Tube-making and Cold Drawing

Abstract

The process of extrusion consists of forcing a billet of metal through a die to produce a continuous length of constant cross section corresponding to the shape of the die orifice. A simple analogy of the process is the squeezing of toothpaste from a tube. Hot extrusion only will be described in this chapter: cold extrusion will be dealt with in Chapter 6 with cold forging processes.

J. D. Radford, D. B. Richardson

6. Sheet Metal Forming and Cold Forging

Abstract

This chapter is concerned with the factory forming processes which produce components that are subsequently assembled into finished products. It is distinct from Chapters 4 and 5, which dealt with primary forming operations for the manufacture of bars, sheets, tubes and forgings—the raw material for factory machining and forming.

J. D. Radford, D. B. Richardson

7. Cutting Tool Geometry and Tool Materials

Abstract

In this chapter some loosely connected aspects of metal cutting are discussed. Tool nomenclature has been dealt with first so that the various tool angles can be defined for use in the other sections. The direction of chip flow across the tool is next considered, to allow a concept of ‘effective’ rake to be established.

J. D. Radford, D. B. Richardson

8. Metal Cutting

Abstract

It is not yet possible to predict with any great accuracy the forces involved in metal cutting, in spite of a large number of theories which have been developed. This is largely due to the extreme complexity and the lack of geometrical constraint which is characteristic of metal cutting. Before explaining the effects of the many variables which are encountered, a description of the simplified theories based on orthogonal machining will be attempted.

J. D. Radford, D. B. Richardson

9. Milling and Broaching

Abstract

At first sight milling and broaching may appear to be vastly dissimilar processes, but this is not so, since surface broaching is somewhat similar to peripheral milling with a cutter of infinite diameter. In fact, surface broaching is being used increasingly in place of milling as a cutting process.

J. D. Radford, D. B. Richardson

10. Economics of Metal Removal

Abstract

The cost of producing components is made up of the raw material, and machining costs and factory overheads. In many machining operations the percentage of raw material utilized in the finished product is extremely low, and in these cases considerable savings can often be made by adopting metal forming or casting rather than metal cutting techniques. By using value analysis, which is an uninhibited approach to reducing product costs, drastic reductions can sometimes be obtained, by changing either the design or the manufacturing process, or both.

J. D. Radford, D. B. Richardson

11. Abrasive Machining

Abstract

Abrasive machining uses hard non-metallic particles to cut the workpiece. Processes within this group include grinding, honing, superfinishing, or abrasive belt machining and lapping. The first three use abrasive particles (often called grits), rigidly held in a wheel, stone or belt, whereas in lapping the particles are contained in a fluid. Unlike most other major machining operations this group of processes can shape workpieces harder than 400 Vickers Hardness Number (HV). Abrasive machining produces smooth surface finishes and enables close control to be maintained over the amount of workpiece material removed; in consequence it is mainly used for finishing operations.

J. D. Radford, D. B. Richardson

12. Recently Developed Techniques of Metal Working

Abstract

A range of new techniques has recently been developed, mainly to cope with (a) the growing use of materials which are difficult to machine, and (b) miniaturization in the electronics industry.

J. D. Radford, D. B. Richardson

13. Fabrication by Welding, Brazing or Adhesion

Abstract

In this chapter it is not proposed to discuss the methods of temporary or semi-permanent attachment of materials such as bolting or riveting, but to confine attention to the more permanent joints produced by welding, brazing or adhesives.

J. D. Radford, D. B. Richardson

14. Casting and Sintering of Metals

Abstract

Casting is a method of producing a large variety of components in a single operation by pouring liquid metal into moulds and allowing it to solidify. Ingots, which are afterwards shaped by further working into a large range of finished products, are originally shaped by casting. Subsequent working improves the mechanical properties of the metal and because of the superior properties of most worked materials, cast parts are often limited to low stress applications.

J. D. Radford, D. B. Richardson

15. Polymer Processing

Abstract

It is estimated that by the 1980s the volume of plastics production will commence to outstrip that of all metals.

J. D. Radford, D. B. Richardson

16. Control of Machine Tools

Abstract

The main headings under which the control of machine tools can be considered are shown in Fig. 16.1. It is not intended to describe the technical details of the various systems, which are amply covered in publications on machine tool design. Rather, it is intended to show the pattern into which the various systems of control fit, and to dwell at greater length on those of comparatively recent introduction, whose potentialities are often not fully appreciated.

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J. D. Radford, D. B. Richardson

17. Metrology

Abstract

Metrology is a branch of engineering concerned with accurate measurement and is of considerable importance to production engineers. It is the purpose of this chapter to indicate briefly some of the ways in which length, angular displacement, shape and surface roughness can be measured. The reader will probably be conversant with some of the simpler measuring equipment, and for this reason the applications of instruments such as the micrometer and vernier caliper will not be discussed.

J. D. Radford, D. B. Richardson

Backmatter