Traditional Machining Technology

Machine Tools and Operations

Helmi Youssef, Hassan El-Hofy

• Editore: CRC Press
• Anno: 2020
• ISBN:
  9781000097139
• Edizione: 2
• Argomento: Technology & Engineering
• Categoria: Materials Science

Traditional Machining Technology describes the fundamentals, basic elements, and operations of general-purpose metal cutting and abrasive machine tools used for the production and grinding of cylindrical and flat surfaces by turning, drilling, and reaming; shaping and planing; and milling processes.

Special-purpose machines and operations used for thread cutting, gear cutting, and broaching processes are included along with semiautomatic, automatic, NC, and CNC machine tools; operations, tooling, mechanisms, accessories, jigs and fixtures, and machine-tool dynamometry are discussed. The treatment throughout the book is aimed at motivating and challenging the reader to explore technologies and economically viable solutions regarding the optimum selection of machining operations for a given task.

This book will be useful to professionals, students, and companies in the industrial, manufacturing, mechanical, materials, and production engineering fields.

1 Machining Technology

1.1 Introduction

Manufacturing is the industrial activity that changes the form of raw materials to create products. The derivation of the word manufacture reflects its original meaning: to make by hand. As the power of the hand tool is limited, manufacturing is done largely by machinery today. Manufacturing technology constitutes all methods used for shaping the raw metal materials into a final product. As shown in Figure 1.1, manufacturing technology includes plastic forming, casting, welding, and machining technologies. Methods of plastic forming are used extensively to force metal into the required shape. The processes are diverse in scale, varying from the forging and rolling of ingots weighing several tons to the drawing of wires less than 0.025 mm in diameter. Most large-scale deformation processes are performed at high temperatures, so that a minimum of force is needed, and the consequent recrystallization refines the metallic structure. Cold forming is used when smoother surface finish and high-dimensional accuracy are required. Metals are produced in the form of bars or plates. On the other hand, casting produces a large variety of components in a single operation by pouring liquid metals into molds and allowing them to solidify. Parts manufactured by plastic forming, casting, sintering, and molding are often finished by subsequent machining operations, as shown in Figure 1.2.

FIGURE 1.1 Classification of manufacturing processes.

FIGURE 1.2 Definition of manufacturing.

Machining is the removal of the unwanted material (machining allowance) from the workpiece (WP) so as to obtain a finished product of the desired size, shape, and surface quality. The practice of removal of machining allowance through cutting techniques was first adopted using simple handheld tools made from bone, stick, or stone, which were replaced by bronze or iron tools. Water, steam, and later electricity were used to drive such tools in power-driven metal cutting machines (machine tools). The development of new tool materials opened a new era for the machining industry in which machine tool development took place. Nontraditional machining techniques offered alternative methods for machining parts of complex shapes in hard, stronger, and tougher materials that are difficult to cut by traditional methods. Figure 1.3 shows the general classification of machining methods based on the material removal mechanism.

FIGURE 1.3 Classification of machining processes. AJM, abrasive jet machining; WJM, water jet machining; USM, ultrasonic machining; AFM, abrasive flow machining; MAF, magnetic abrasive finishing; CHM, chemical machining; ECM, electrochemical machining; EDM, electrodischarge machining; LBM, laser beam machining; PBM, plasma beam machining.

Compared with plastic-forming technology, machining technology is usually adopted whenever part accuracy and surface quality are of prime importance. The technology of material removal in machining is carried out on machine tools, which are responsible for generating the motions required for producing a given part geometry. Machine tools form around 70% of operating production machines and are characterized by their high production accuracy compared with metal-forming machine tools. Machining activities constitute approximately 20% of the manufacturing activities in the United States.

This book covers the different technologies used for material removal processes in which traditional machine tools and operations are employed. Machine tool elements, drives, and accessories are introduced for proper selection and understanding of their functional characteristics and technological requirements.

1.2 History of Machine Tools

The development of metal-cutting machines (once briefly called machine tools) started with the invention of the cylinder, which was changed to a roller guided by a journal bearing. The ancient Egyptians used these rollers for transporting the required stones from a quarry to the building site. The use of rollers initiated the introduction of the first wooden drilling machine, which dates back to 4000 BC. In such a machine, a pointed flint stone tip acted as a tool. The first deep-hole drilling machine was built by Leonardo da Vinci (1452–1519). In 1840, the first engine lathe was introduced. Maudslay (1771–1831) added the lead screw, back gears, and the tool post to the previous design. Later, slide ways for the tailstock and automatic tool feeding systems were incorporated. Planers and shapers have evolved and were modified by Sellers (1824–1905). Fitch designed the first turret lathe in 1845. That machine carried eight cutting tools on a horizontally mounted turret for producing screws. A completely automatic turret lathe was invented by Spencer in 1896. He was also credited with the development of the multispindle automatic lathe. In 1818, Whitney built the first milling machine; the cylindrical grinding machine was built for the first time by Brown and Sharpe in 1874. The first gear shaper was introduced by Fellows in 1896. I...

Indice dei contenuti

• Cover
• Half-Title
• Title
• Copyright
• Dedication
• Contents
• Preface
• Acknowledgments
• Author Biographies
• List of Symbols
• List of Acronyms
• Chapter 1 Machining Technology
• Chapter 2 Basic Elements and Mechanisms of Machine Tools
• Chapter 3 General-Purpose ­Metal-Cutting Machine Tools
• Chapter 4 General-Purpose Abrasive Machine Tools
• Chapter 5 Thread-Cutting Machines and Operations
• Chapter 6 Gear-Cutting Machines and Operations
• Chapter 7 Turret and Capstan Lathes
• Chapter 8 Automated Lathes
• Chapter 9 Numerical Control and Computer Numerical Control
• Chapter 10 Automated Manufacturing Systems
• Chapter 11 Machine-Tool Dynamometers
• Index