Mechanical Workshop Practice

Transcription

1 Second Edition Mechanical Workshop Practice K.C. John

2 MECHANICAL WORKSHOP PRACTICE SECOND EDITION K.C. JOHN Professor and Head Department of Production Engineering Vidya Academy of Science and Technology Thalakkottukara, Thrissur Kerala New Delhi

3 MECHANICAL WORKSHOP PRACTICE, Second Edition K.C. John 2010 by PHI Learning Private Limited, New Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Second Printing (Second Edition) September, 2010 Published by Asoke K. Ghosh, PHI Learning Private Limited, M-97, Connaught Circus, New Delhi and Printed by Rajkamal Electric Press, Plot No. 2, Phase IV, HSIDC, Kundli , Sonepat, Haryana.

4 Contents Preface... ix Module A: Introduction to Workshop Practice 1. WORKSHOP PROCESSES Classification of Manufacturing Processes Primary Shaping Processes Metal Casting Rolling Forging Extrusion Metal Drawing Powder Metallurgy Oxy-Gas Cutting Press Work Sheet Metal Work Metal Spinning Secondary Shaping Processes Joining Processes Welding 15 iii

5 iv Contents Brazing and Soldering Screwing Riveting Shrink Fitting Adhesive bonding Surface Finishing Processes Processes Changing the Material Properties Heat Treatment of Ferrous Metals Heat Treatment of Nonferrous Metals Cold Working of Metals Hot Working of Metals Shot Peening Materials for Workshop Practice Classification of Engineering Materials 27 Exercises WORKSHOP PRACTICE AND RECORD WRITING Workshop Processes for Practice Safety Measures Preparing for the Workshop Practice Writing of the Work Record Writing of Work Record for a Study Writing of Work Record for a Practice Writing of the Fair Record 40 Exercises 41 Module B: Hand Working Processes 3. FITTING Introduction to Bench Work and Fitting Work Holding Devices Work Bench Bench Vice Hand Vice V-block with Clamp Cutting Tools Files Hack Saw Chisels Hammers Scrapers Drills and Reamers Taps and Dies 56

6 Contents v 3.4 Measuring and Marking Tools Surface Plate Engineer s Try Square Scribers Punches Steel Rule Vernier Caliper Outside and Inside Calipers Dividers Combination Set Micrometer Vernier Height Gauge Miscellaneous Gauges Tools for Assembling Spanners Pliers Screw Drivers Allen Keys Fitting Processes Marking Out Hack Sawing Chipping Filing Scraping Drilling and Reaming Tapping and Dieing Assembling Models for Fitting Practice 70 Exercises ARC WELDING Principle of Shielded Metal Arc Welding Arc Welding Principle Power Supply Welding Positions Welding Electrodes Arc Welding Equipment and Accessories Welding Equipment Operator Accessories Types of Welds Types of Welded Joints Edge Preparation Number and Arrangement of Runs 84

7 vi Contents 4.5 Welding Symbols Defects in Weld Welding Practice Welding Procedure Striking and Maintaining the Arc Tack Welding Weaving the Electrode Safety Precautions 90 Exercises SHEET METAL WORK Metals Used Hand Tools Measuring Tools Marking Tools Cutting Tools Forming Tools Joining Tools Sheet Metal Operations Laying Out of Patterns Cutting or Shearing Bending and Forming Drawing Edge Forming Joint Making Soldering Riveting Sheet Metal Work Practice 104 Exercises CARPENTRY Materials Used in Carpentry Timber Classification of Wood Indian Timber Plywood Auxiliary Materials Tools for Wood Working Measuring and Marking Tools Cutting Tools Striking Tools Planing Tools Work Holding Devices Miscellaneous Tools 121

8 Contents vii 6.3 Wood Working Processes Carpentry Joints Wood Working Machines Carpentry Practice 129 Exercises BLACKSMITHY Principle of Smithing and Forging Heating Equipment Tools and Appliances Work Supporting Tools Hammers Tongs Metal Shaping Tools Measuring Tools Heating of Metal Forging Operations Upsetting or Jumping Drawing Out or Drawing Down Punching and Drifting Bending and Twisting Setting Down and Finishing Cutting Smithing Practice Smithing Procedure Safety Measures 143 Exercises FOUNDRY Introduction to Metal Casting Processes Sand Casting Process Sand Mould Patterns Types of Patterns and Core Boxes Pattern Allowances Pattern Making Tools and Equipment for Hand Moulding Hand Moulding Moulding Sand and Its Preparation Bench Moulding Melting and Pouring Moulding Practice 159 Exercises 161

9 viii Contents 9. PLUMBING Introduction Pipes and Their Joints Pipe Fittings Valves and Meters Plumping Fixtures (Sanitary fittings) Sketching of Piping Layouts Water Supply System Rain Water Disposal System Sewage/Wastewater Disposal System Plumbing for Industries Plumber s Tools Accessories for Plumbing Plumbing Practice 190 Exercises 197 Module C: Machining Processes 10. TURNING Introduction to Turning Principle of Turning Metal Cutting and Chip Formation Cutting Speeds for Turning Types of Turning Machines Centre Lathe (Engine Lathe) Accessories and Attachments Tools for Measuring and Machining Measuring and Marking Tools Cutting Tools Turning Operations Turning Practice 217 Exercises 218 APPENDIX SUGGESTED READING INDEX

10 Preface In the modern engineering curriculum, with the emphasis on engineering science, workshop and laboratory practices have acquired greater importance in the recent years. With major advancements in precise instrumentation and computerized manufacturing techniques, the same has become more sophisticated and specialized field. To gain a basic knowledge of manufacturing process, a student entering the first year of degree or diploma must undertake a course on workshop practice. This gives him/her an overall knowledge about various engineering materials, tools, equipment and processes which are common in the engineering field. Multiple requests from my students and colleagues for a good supporting textbook were my motivation to write the book Mechanical Workshop Practice. The favourable and warm reception of first edition of the book Mechanical Workshop Practice gave me satisfaction and encouragement to bring out the second edition. I have utilized this opportunity to revise the book little and add one chapter on Plumbing. This book consists of three modules. Module A is an introduction to workshop practice. Its first chapter explains general principles and layout of workshop processes such as primary and secondary shaping processes, metal joining methods, surface finishing, heat treatments and the materials for workpieces and tools. The second chapter describes the importance of safety measures to be followed as well as the procedure of writing the work and fair records of the practice. Module B deals with the hand working processes such as fitting, arc welding, sheet metal work, carpentry, blacksmithy and foundry. Each chapter in this module initially ix

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