Fitting & Turning. NQF Level 2. LL Maraschin LECTURER S GUIDE TVET FIRST

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Clyde Lawson
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1 Fitting & Turning NQF Level 2 LL Maraschin LECTURER S GUIDE TVET FIRST

2 Fitting & Turning NQF Level 2 Lecturer s Guide LL Maraschin

3 Fitting & Turning NQF Level 2 Lecturer s Guide LL Maraschin, 2012 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying, recording, or otherwise, without the prior written permission of the copyright holder or in accordance with the provisions of the Copyright Act, 1978 [as amended]. Any person who does any unauthorised act in relation to this publication may be liable for criminal prosecution and civil claims for damages. First published in 2012 by Troupant Publishers [Pty] Ltd PO Box 4532 Northcliff 2115 Distributed by Macmillan South Africa [Pty] Ltd ISBN: It is illegal to photocopy any page of this book without written permission from the publisher. While every effort has been made to ensure the information published in this work is accurate, the authors, editors, publisher and printers take no responsibility for any loss or damage suffered by any person as a result of reliance upon the information contained herein. The publisher respectfully advises readers to obtain professional advice concerning the content. While every effort has been made to trace the copyright holders and obtain copyright permission from them, in some cases this has proved impossible due to logistic and time constraints. Any copyright holder who becomes aware of infringement on our side is invited to contact the publisher. Note: Any reference to Further Education and Training (FET) in this book should be taken to mean Technical and Vocational Education and Training (TVET). To order any of these books, contact Macmillan Customer Services at: Tel: (011) Fax: (011) customerservices@macmillan.co.za

4 Contents Topic 1: Grinding and sharpening...1 Module 1 Correct safety procedures and care when grinding tools and drill bits...1 Module 2 Understanding the grinding processes associated with tools and drill bits...2 Module 3 Plan and prepare for tool grinding...3 Module 4 Grind tools and drill bits...4 Module 5 Store equipment and record information on completed work...5 Topic 2: Drilling machines...7 Module 6 Work safely with drilling machines...7 Module 7 Demonstrate an understanding of drilling machines and drilling processes...7 Module 8 Prepare for work activity and set the drilling machine...9 Module 9 Perform drilling operations...9 Module 10 Apply quality checks and record information on completed work...10 Topic 3: Hand threading and reaming...13 Module 11 Working safely during threading and reaming work...13 Module 12 Screw-threads...13 Module 13 Hand taps, stocks and dies, and reamers...14 Module 14 Planning and preparing materials and equipment for threading and reaming...15 Module 15 Producing threads and reaming a work piece...16 Module 16 Quality checks and storage of equipment...16 Topic 4: Keys and fasteners...19 Module 17 Working safely with keys and fasteners...19 Module 18 Keys and keyways...19 Module 19 Fasteners...20 Topic 5: Centre lathe...24 Module 20 Safety rules and precautions when working with a lathe...24 Module 21 Preparing the operation sheet...24 Module 22 Preparing for the work activity...26 Module 23 Setting the lathe...27 Module 24 Performing turning operations...28 Module 25 Applying quality checks on machined components...29 Module 26 Recognising and reporting problems, changes and/or malfunctions...29 Topic 6: Milling machine...34 Module 27 Parts and uses of a milling machine...34 Module 28 Follow safety rules and maintain safety precautions...34 Module 29 Prepare operation sheet...35 Module 30 Prepare for work activity...36 Module 31 Set milling machine...37 Module 32 Perform milling operations...37 Module 33 Apply quality checks on machined component...38 Module 34 Recognise and report problems, changes and/or malfunctions while operating...38

5 Topic 1: Grinding and sharpening Module 1 Correct safety procedures and care when grinding tools and drill bits Subject Outcome Learning Outcomes Assessment Standards Assessment Tasks/ Activities 1.1: Explain correct safety procedures and care when grinding tools and drill bits. Explain general worksite health and safety practices. Explain good housekeeping. Explain the safety precautions before and after using the grinding machine. Explain the importance of a clean work area. Describe the necessity of cleaning equipment, materials and machines. Identify appropriate personal protective clothing (PPC) and personal protective equipment (PPE) to be worn during the grinding process. Explain why it is important to wear the right PPC and use the right PPE during the grinding operation. Identify and remove any flammable materials present that might cause an unsafe work environment. General worksite health and safety practices are explained. Good housekeeping is explained. Safety precautions before and after using the grinding machine are explained. The importance of a clean work area is explained. The necessity of cleaning equipment, materials and machines is described. Appropriate personal protective clothing (PPC) and personal protective equipment (PPE) to be worn during the grinding process are identified. The importance of wearing the right PPC and using the right PPE during the grinding operation is explained. Flammable materials that might cause an unsafe workenvironment are identified and removed. Assessment activity 1.1 Assessment activity Not following good housekeeping procedures can lead to: injury to workers and others financial consequences due to loss of productivity a demoralised workforce. 2. Solvents should be disposed of by following company policies and procedures. If there are no policies and procedures, then they should be placed in a marked container, sealed, stored and labelled. A company dealing with the disposal of hazardous materials can then be contacted to remove them. 3. PPE required to carry out grinding operations safely: safety glasses or face mask SABS-approved overall safety shoes or boots ear protection cap or hair net if you have long hair. Topic 1: Grinding and sharpening 1

6 Module 2 Understanding the grinding processes associated with tools and drill bits Subject Outcome Learning Outcomes Assessment Standards Assessment Tasks/ Activities 1.: Demonstrate an understanding of grinding processes associated with tools and drill bits. Identify different types of grinding wheels. Determine the rotational speed of a drilling machine. Identify the types of angles of grinding tools and drill bits. Identify types of material using typical tests in the workshop. Explain the correct sequence of activities when grinding cutting tools and drill bits. Describe the implications of not adhering to the correct sequence of activities and operations. Different types of grinding wheels are identified. The rotational speed of a drilling machine is determined. Types of angles of grinding tools and drill bits are identified. Types of material using typical tests in the workshop are identified. The correct sequence of activities during grinding cutting tools and drill bits is explained. The implications of not adhering to the correct sequence of activities and operations are described. Assessment activities 2.1, 2.2 and 2.3 Assessment activity 2.1 Assessment activity 2.2 Assessment activity 2.3 Assessment activity When switching on the grinder, stand to one side in case the wheel bursts so that pieces of abrasive fly past you. 2. The two main types of abrasives and the symbols used to identify them are: A = aluminium oxide C = silicon carbide. 3. The structure of a grinding wheel refers to the grain spacing. 4. Mounting a grinding wheel: Select the correct wheel for the material you want to grind. Check for the wheel for soundness. Clean all the components including the wheel bay. Use new paper blotters on each side of a new wheel. If required, use new plastic spacers in the bore of the wheel. Never force the wheel onto the spindle. Tighten the wheel gently without tapping the spanner and only enough to hold the wheel firmly. Over-tightening can damage the wheel. Correctly replace the safety guards. Stand aside and set the machine in motion. Let the machine run idle for at least one minute. Then trim up the wheel with a wheel dresser. Finally, stop the machine and reset the tool rest to within 2 mm of the wheel and parallel to it. 2 Topic 1: Grinding and sharpening

7 Module 3 Plan and prepare for tool grinding Subject Outcome Learning Outcomes Assessment Standards Assessment Tasks/ Activities 1.3: Plan and prepare for tool grinding. Demonstrate knowledge of different grades and shapes of grinding wheels. Establish material to be cut/drilled with the tool/ drill bit. Identify the types of angles (helix, rakes, clearance etc.). Identify the type of material a tool is made of. Identify different types of grinding wheels and codes of classification. Inspect grinding wheels. Dress grinding wheels and adjust the tool rest. Identify damaged or substandard components and equipment and take appropriate corrective action. Knowledge of different grades and shapes of grinding wheels is demonstrated. The material to be cut/ drilledwith the tool/drill bit is established. The types of angles (helix, rakes, clearance etc.) are identified. The type of material a tool is made of is identified. Different types of grinding wheels and codes of classification are identified. Grinding wheelsare inspected. Grinding wheelsare dressed and the tool rest is adjusted. Damaged or substandard components and equipment are identified and appropriate corrective action is taken. Assessment activities 3.1, 3.2, 3.3 and 3.4 Assessment activity 3.1 Assessment activity 3.2 Assessment activity 3.3 Assessment activity A detailed explanation of the term tempering is as follows: Because hardened steel becomes brittle, even a slight impact may cause the metal to fracture. Tempering is a heat treatment that reduces the brittleness of a metal without significantly lowering its hardness and strength. All hardened steels must be tempered before use. 2. Case hardening is a simple method of hardening steel. It is less complex than hardening and tempering. This technique is used for steels with a low carbon content. Carbon is added to the outer surface of the steel to a depth of approximately 0,03 mm. Advantages of this method of hardening steel are that the inner core is left untouched and therefore still has properties such as flexibility, and the steel remains relatively soft. 3. A chip breaker is a tool that can be ground into a cutting tool. A chip breaker is particularly important when cutting ductile metals such as mild steel, aluminium and copper as they tend to produce a long, continuous chip. These chips are difficult to handle, take up a lot of space, are razor sharp and can be highly dangerous if not controlled. Topic 1: Grinding and sharpening 3

8 Module 4 Grind tools and drill bits Subject Outcome Learning Outcomes Assessment Standards Assessment Tasks/ Activities 1.4: Grind tools and drill bits. Inspect and assess drill bits and tool condition. Sharpen the drill bit/tool to the manufacturer s specifications and to meet job requirements. Determine and complete set-up angles using the correct measuring instrument. Position the drill bit on the rest. Sharpen the drill bit to meet the required angle for different materials. Check tool and/or drill bits for compliance with specifications and apply further grinding if necessary. Apply cooling during the grinding to prevent overheating of the grinding surface. Apply appropriate safety practices during the grinding process. Drill bits and tool condition are inspected and assessed. The drill bit/tool is sharpened according to the manufacturer s specifications and job requirements. Set-up angles are determined and completed using the correct measuring instrument. The drill bit is positioned on the rest. The drill bit is sharpened to meet the required angle for different materials. The tool and/or drill bits are checked for compliance according to specifications and further grinding is applied where necessary. Cooling is applied during the grindingto prevent overheating of grinding surface. Appropriate safety practices are applied during the grinding process. Assessment activity 4.1, 4.2 and 4.3 Assessment activity 4.1 Assessment activity 4.2 Assessment activity The included point angle when drilling steel is Two measuring instruments that can be used to check a drill bit are the protractor and the drill gauge. 3. The clearance angle on a drill bit should be The cutting lips should be equal in length and height otherwise the drill will produce oversize holes and holes that are skew. 4 Topic 1: Grinding and sharpening

9 Module 5 Store equipment and record information on completed work Subject Outcome Learning Outcomes Assessment Standards Assessment Tasks/ Activities 1.5: Store equipment and record information on completed work. Clean grinding tools and equipment. Store grinding tools and equipment in a safe place. Accurately record information on completed job. Store information in a safe place. Explain incidents and problems related to tool grinding. Grinding tools and equipment are cleaned. Grinding tools and equipment are stored in a safe place. Information on completed job is recorded accurately. Information is stored in a safe place. Incidents and problems related to tool grinding are explained and reported. Summative assessment Summative assessment 1. The purpose of sharpening is to prepare the cutting edges of tools for cutting materials in manufacturing processes. This is achieved by grinding and whetting blunt edges. 2. The advantage of off-hand drill sharpening is that you can do it at any grinding machine immediately without any time-consuming preparations. 3. Tools that can be treated using off-hand sharpening include steel scribers, the scribers of beam trammels and scribing blocks, centre punches, chisels, all kinds of drill bits, screwdrivers and scrapers. 4. The components of a grinding wheel are the abrasive and the bonding agent. 5. Wheels used for off-hand sharpening are corundum and silicon carbide wheels. 6. A soft to medium-hard corundum wheel with medium grain size is used for sharpening tools made of tool steel. 7. During grinding irregularly shaped abrasive grains shave fine segmental chips from the work piece. 8. Self-sharpening of the grinding wheel means that dull abrasive grains are loosened by the pressure of the work piece and they give way to the sharp abrasive grains behind them. 9. The working movement for sharpening drills is to place the main cutting edge of the drill in a horizontal position and then to press the drill upwards and simultaneously to the right. 10. Angles to be maintained when grinding drills with a standard drill point are: angle of point 118 complementary angle of the drill edge 59 clearance angle of Grinding faults that we can detect by eyesight are: main cutting edges with unequal length main cutting edges with unequal angles hollow-ground main cutting edges. 12. Drill-pointing is the lateral resharpening of the drill edge in a vertical position. 13. It is necessary to dress grinding wheels to guarantee true running and surface finish of the grinding wheel. Topic 1: Grinding and sharpening 5

10 14. The angles that make up a single point right-hand lathe tool are shown in the diagrams below: 15. A chip breaker is a tool that can be ground into a cutting tool. A chip breaker is particularly important when cutting ductile metals such as mild steel, aluminium and copper as they tend to produce a long, continuous chip. These chips are difficult to handle, take up a lot of space, are razor sharp and can be highly dangerous if not controlled. 16. Six different types of cutting tools used on a lathe: Boring Threading tool Parting tool Righthand tool Lefthand tool Left-hand and right-hand side facing tools Round nose tools Recessing tool Form tools 6 Topic 1: Grinding and sharpening

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