MEM05 Metal and Engineering Training Package MEM07005C Perform general machining Learner guide Version 1.1 Training and Education Support Industry Skills Unit Meadowbank Product code: 5790
Acknowledgments The TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank would like to acknowledge the support and assistance of the following organisations and people in the production of this learner guide. Hare and Forbes Machinery House Fitting and Machining (Ron Culley) Electricity Commission of NSW (Lathe Manual) BHP (Machinist Manual) Blackwoods ISCAR TAFE NSW, Fitting and Machining (Theory Book 2) Writer: Andrew Gill TAFE NSW Reviewers: Mark Pollard (South Western Sydney Institute) Greg Carrol (Western Institute) Project Manager: Stephen Davies Education Programs Manager TAFE NSW Enquiries Enquiries about this and other publications can be made to: Training and Education Support Industry Skills Unit, Meadowbank Meadowbank TAFE Level 3, Building J, See Street, MEADOWBANK NSW 2114 Tel: 02-9942 3200 Fax: 02-9942 3257 The State of New South Wales, Department of Education and Training, TAFE NSW, Training and Education Support Industry Skills Unit, Meadowbank, 2011. Copyright of this material is reserved to TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank. Reproduction or transmittal in whole or in part, other than for the purposes of private study or research, and subject to the provisions of the Copyright Act, is prohibited without the written authority of, TAFE NSW Training and Education Support Industry Skills Unit, Meadowbank ISBN 978-1-74236-498-8 Developed by Training & Education Support Industry Skills Unit, Meadowbank TAFE NSW 2011
Table of Contents Introduction... 9 1. General introduction... 9 2. Using this learner guide... 9 3. Prior knowledge and experience... 11 4. Unit of competency overview... 11 5. Assessment... 16 Topic 1: The centre lathe... 21 Introduction and safety... 21 Lathe maintenance... 29 Mounting work in the lathe... 30 Lathe chucks... 30 Mounting a chuck... 32 Holding work in a chuck... 35 Setting up in a four jaw chuck... 36 Types of cutting tools... 37 Cutting tool materials... 40 Setting up the cutting tool... 44 Feed and depth of cut... 48 Types of cutting operations... 50 Lathe centres... 58 Principles of metal cutting... 59 Cutting fluids... 62 Review questions... 66 Topic 2: The milling machine... 69 Types of milling machines... 69 Parts of the vertical mill... 70 Vertical mill controls... 71 Movements of the vertical mill... 73 Movements of the vertical mill head... 74 Developed by Training & Education Support Industry Skills Unit, Meadowbank TAFE NSW 2011
The bed mill... 77 Combination horizontal/vertical mill... 77 Horizontal/universal mill... 77 Milling safety... 79 Mill maintenance... 80 Types of milling cutters... 81 Cutting tools for vertical milling... 82 Selection of milling cutters... 83 Care and maintenance of milling cutters... 83 Mounting milling cutters... 84 Mounting the work piece... 87 Clamping in a vice... 90 Milling in the vice... 92 Milling operations... 93 Conventional and climb milling... 96 Speeds and feeds for milling... 98 Locating the work piece edge...102 Review questions...103 Topic 3: Radial arm drill... 107 Introduction...107 Radial drilling machine types...110 Tool holding devices...111 Work holding...112 Safety precautions...113 Drilling operations...114 Setting up in the radial drill...116 Types of cutting tools...117 Cutting speeds and RPM calculations...124 Review questions...125 Developed by Training & Education Support Industry Skills Unit, Meadowbank TAFE NSW 2011
Topic 4: Surface grinding... 129 Purpose...129 Introduction...129 Machine types...129 Grinder classifications...130 Surface grinder features...131 Operation of the surface grinder...131 General set-up and installation...133 Dressing and truing...136 Operating procedure...138 Using coolant...139 Maintenance...140 Safety...142 Abrasive wheels...143 Holding work...144 Review questions...150 Job 1: Introduction to the lathe...155 Job 2: Turning to size...161 Job 3: Turn, bore, drill and ream in the lathe...165 Job 4: Introduction to the mill...168 Job 5: Milling to size...172 Job 6: Parallel strip...175 Job 7: Toolmakers Clamp...184 Job 8: Tee Tap Wrench...189 Resource Evaluation Form... 195 Developed by Training & Education Support Industry Skills Unit, Meadowbank TAFE NSW 2011
Topic 1: The centre lathe Introduction and safety The Lathe is a machine tool in which the work can be held and rotated. A cutting tool is held and either moved along or across the work to produce cylindrical shapes (turning) or flat surfaces (facing). The speed at which the work rotates can be varied as can the speed at which the tool travels (feed). This is necessary because of the different diameters and types of materials that have to be turned. There are many and varied types of operations that can be carried out on the lathe eg, threading, boring, drilling, reaming, form turning etc. Workpiece sizes are determined by the largest diameter and length of work which can be accommodated. The Work, Health and Safety Act 2011 (WHS Act) and WHS Regulations are enforced throughout all Australian States and Territories. This legislation is aimed at providing consistency, certainty and clarity across Australia making it easy to understand workplace health and safety responsibilities. Consequently this act and its regulations requires both employers and employees to take every reasonable step to work safely and responsibly in the workplace. There are no short cuts to working safety, its everyone s responsibility to manage and minimise potential risks in the workplace, report faulty equipment as well as unsafe environments. Detailed information relating to the WHS Act and regulations can be found on: WorkCover Authority of NSW website; www.workcover.nsw.gov.au or on Safe Work Australia; www.safeworkaustralia.gov.au Lathe safety precautions Like any machine tool the lathe must be operated in a safe manner and the operator must concentrate on what is being done on the machine at all times otherwise serious injury may occur from poor operating procedures. Possible injuries include: burns, cuts, eye injury and possible entanglement. The following points should be observed to prevent possible injury. Wear suitable close fitting clothing. Wear approved eye protection. Use correct lifting methods. Keep tools or jobs from the headstock (moving parts). Use correct tools and equipment. Keep work area tidy. Keep hands away shavings. Do not stop the machine with your hands. Always remove the chuck key from the chuck. Clothing torn off the lathe operator and wrapped around the job TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011 Page 21 of 198
Keep your eyes on the machine while it is operating. Switch the power off when setting the job in the lathe. Ensure all locking pins are secured when changing chucks. Beware of sharp tools in the tool post. Lathe dimensions When comparing the size and working capacities of metal lathes there are several key dimensions to consider. They include: Swing over the bed Distance between centres Swing over the carriage Diameter of spindle through hole Centre lathe components Digital readout Chuck guard Head stock Feed box Lead screw The diameter of the largest work piece that can be rotated on the spindle without hitting the bed. The longest piece of work that can be held between centres. The diameter of the largest work piece that can rotate over the carriage without hitting it. The diameter of the hole that passes through the spindle. Tool post Top slide Tail stock Carriage Apron Feed screw Start/stop Swarf tray E stop Cross slide Foot brake Page 22 of 198 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011
Heavily ribbed Vee bed Machine ways 1. Bed Bed J Jaw chuck Headstock Feed gear box Lead screw Feed shaft Tool post The bed is the foundation of the lathe. It is the part that aligns and supports the other parts of the lathe. Made from high quality fine grain cast iron, it is heavily ribbed to remain distortion free. The top surface of the bed has two Vee's and two flats, one of each for the Saddle and one of each for the Tailstock (Fig 1) and precision machined to accurately align other parts. The top surface of the bed is called "ways" or "slides". On some lathes they may be hardened to give greater wear resistance. Take care of the bed slide ways as worn or damaged ways cannot provide accurate alignment in the moving parts. Thus poor quality work will result. Cross side Compound side Saddle Froward/Reverse lever Tallstock Figure 1 Figure 2 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011 Page 23 of 198
2. Headstock The headstock is the part of the lathe that provides the means of holding and rotating the work. It consists of a cast iron housing fixed to the left hand end of the bed. This housing contains a spindle which is a hollow shaft; it is supported with bearings in alignment to the bed. The right hand end of the spindle has a tapered bore to accommodate a Morse standard taper centre. The spindle is interconnected with gears, (see Fig 2 below) and pulleys to the motor (Fig 3) to provide motion and speed variation. The right hand end of the spindle also has provision for the mounting of holding devices such as chucks, driving plates, face plates etc. The headstock levers on a modern gear head lathe (see Fig 4 below) allow quick changes in speeds and feed. Index plates are available on or below the headstock noting where various levers must be positioned to achieve the proper speed or feed or thread turning. Index plates usually show positions for both inch and metric threads. Figure 3 Figure 4 Page 24 of 198 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011
Starting and stopping To start or stop the spindle, a non-rotating starting/stopping shaft runs from the headstock for the full length of the bed. It will have at least one handle attached like the one shown in the photo with the knob. On the machine shown, pulling up on the handle from the neutral position starts the spindle in the counter clockwise direction (the correct direction for 99% of lathe operations). Note: Know your machine! Many machines require you to push the start handle down for normal operations. For the same handle, in the neutral position, a slight shift to the right and pushing down on the handle will cause the spindle to rotate clockwise. For both scenarios a movement back to the neutral position will turn off the motor. The spindle will then coast down to a stop. Lever actuated starting and stopping of the spindle is very common. Most free standing lathes (not bench lathes) have a foot brake like the one shown below. Pressing on the foot brake turns off the motor and applies a braking pressure to the spindle. The advantage of the foot brake is instant stopping and, therefore, added safety. 3. Tailstock Brake Start/stop lever Lathe showing brake and start/stop lever The tailstock consists of a base (1), body (2) and spindle (3). The base is located on the ways and provides accurate alignment with the headstock. The body is accurately located on the base and is bolted in position. It can be moved a small distance 90 to the bed to provide for realignment to the headstock or to allow for the offsetting of the tailstock for machining of tapers. The spindle is located in the body and its axis is 1 normally aligned with the axis of the headstock. The left hand end of the spindle is bored out to a Morse standard taper to take a centre or various other attachments that may be used on the lathe. It may be moved in and out by means of a hand wheel (4) and threaded spindle. The spindle clamp (5) locks the spindle in any position in the body. The body clamp lever (6) locks the tailstock in any position on the bed. 3 2 5 6 4 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011 Page 25 of 198
4. Carriage The carriage is the part of the lathe that provides the method of holding the cutting tool and moving it accurately along or across the work. The carriage consists of: Apron The apron is attached to the front of the saddle. It contains the mechanism for controlling and moving the carriage. The apron has an auto feed knob, a shift-feed knob (left middle), and a threading (left) and feed engagement handle (bottom). The auto feed handle will engage or disengage all feed motions. The shift-feed handle will change the feed from the carriage to the cross slide or visa versa. Somewhere on the headstock there will be a feed-reversing handle. This handle changes the direction of rotation of the feed rod, thus reversing the feed direction of the cross slide and the carriage. Page 26 of 198 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011
Saddle The saddle is the part that spans the bed. It locates accurately on the ways and moves between the headstock and tailstock. Cross slide Mounted on top of the saddle it provides cross movement the tool, at 90 to the spindle. Movement of the cross-slide is controlled by the cross-slide screw. A graduated dial attached to the screw can be used to measure cross-slide movement. It is used to set a measured depth of cut. Compound rest Is bolted to the top of the cross slide and can be swivelled horizontally through 360. The angle can be set by means of the graduated scale around the base. Top slide Fitted to the top of the compound rest it supports the tool post. It has limited travel but combined with the compound slide it can be used for the machining of short tapers. Graduated dials Graduated dials are attached to the cross and top slides and can be used to measure cross/top slide movement. They are used to set a measured depth of cut. The value of each graduation marked on the dial may vary with the make of the lathe. Some manufacturers may choose to use 0.02 mm per graduation, others 0.01 mm per graduation or others which may be different. Well engineered machines will have graduations clearly indicated on or near the dial. The radial distance the tool moves into the work piece, is referred to as the depth of cut. The diameter of the work piece will be reduced by twice this amount. NB: Some lathes have "Diameter" dials. If you need to reduce the diameter by 2 mm you move the handwheel 2 mm. TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011 Page 27 of 198
Tool post Attached to the top of the top slide it securely holds the tool. Common tool posts are called a 4 station tool post and can hold 4 tools at once. This type of tool post can be swivelled through 360 and can usually be locked in any position. Quick change tool post video The feed mechanism http://www.youtube.com/watch?v=vkew_bcwj3e&feature=player _embedded The feed mechanism consists of: Quick change gearbox Mounted on the front left hand end of the bed, the quick change box is driven directly through gears by the headstock spindle. Using the levers mounted on the front of the gearbox the speed at which the feed shaft or lead screw rotates can be altered in relation to the revolutions of the work. Gear box panel Feed shaft Is driven by the quick change gearbox and provides power feed to the carriage and cross slide. It can be rotated in either direction and the rate of feed can be altered with selector levers on the front of the quick change gearbox. Lead screw Mounted on the front of the lathe, it is driven through the quick change gearbox. It enables screw threads to be cut on the lathe. The speed of rotation of the lead screw can be altered in relation to the spindle speed to allow for different pitch threads to be cut. The direction of rotation can also be reversed to cut either right or left hand threads. Page 28 of 198 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011
Feed shift knobs (1) This changes the transmission of power either to the carriage for longitudinal feed or to the cross slide for cross feed. Feed select lever (2) When this lever is engaged power is connected from the feed shaft to the carriage or cross slide. 3 1 Lead screw engagement lever (3) This connects the lead screw to the carriage for thread cutting operations. Lathe maintenance Cleaning and lubrication The centre lathe is a precision machine tool and must be treated with great care. Regular cleaning and maintenance will help to assure that the lathe will maintain its service life and accuracy for many years. To keep a metal lathe in good condition, adhere to a set of proven procedures. From constant cleaning to preventative maintenance, it is good practice to keep everything clean and clear in a machining environment. By removing metal chips and using sharp tooling, you can be sure that your dimensions will be correct as specified in the print. Prior to operation Check your work area is free from clutter Ensure all guards are in place Check coolant levels and that the ways are clean and have been lubricated Ensure the clutch lever is neutral position. Check the oil levels in the quick change box and the carriage apron Start the lathe and check the oil level in the headstock. 2 Feed and lead screw levels Removing swarf TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011 Page 29 of 198
Post operation The machine is to be thoroughly swept clean of all shavings and swept from the machine down to the tray. N.B. Do not use compressed air to blow swarf away. The scrap tray is to be emptied and swept clean (wear leather gloves). The slides are wiped clean and dry and lightly oiled to prevent rust. Wipe bed free from All exposed metal parts are to be lightly coated with oil to prevent rust. Sweep the floor area around your machine. Mounting work in the lathe Introduction Work may be mounted to the Lathe spindle using various methods depending on the size, shape and operations to be performed on the job. The chuck is the most common and practical. Lathe chucks Four jaw independent chuck Oil bed after cleaning This chuck is used to hold regular and irregular or odd shaped work. The chuck has four jaws that can be moved independently of each other. Work can be held very firmly as each jaw opposes each other. Figure 1 Concentric circles marked on the face of the chuck assist in setting up the work as shown in Fig 1 above. Work can be set up running very true by adjusting the jaws and checking with a dial indicator. Each jaw can be reversed independently to enable odd shaped work to be held and to enable large diameter work to be held. Jaws should never protrude past the outside of the chuck more than one third of their length. Page 30 of 198 TAFE NSW (Training & Education Support, Industry Skills Unit Meadowbank) 2011