PowerPoint to accompany
Technology of Machine Tools 7th Edition
Krar • Gill • Smid
Week 1: Introduction Dr. Taufik Faculty of manufacturing Engineering Universiti Teknikal Malaysia Melaka
McGraw-Hill
Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved
PowerPoint to accompany
Technology of Machine Tools 7th Edition
Krar • Gill • Smid
History of Machines Unit 1
McGraw-Hill
Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved
1-3
Objectives • The development of tools throughout history • The standard types of machine tools used in shops • The newly developed space-age machines and processes
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History of Machine Tools • Began during stone age (<50,000 years ago) – Hand tools of wood, animal bones, or stone
• Bronze age (4500 to 4000 b.c.) – Copper and bronze implements – Power-operated (animal power)
• Iron age (1000 b.c.) – Iron replaced bronze – Domesticated animals provided power – Commodities handmade by skilled craftspeople
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History of Machine Tools • Machine age (~300 years ago) – Explored new sources of energy (water)
• Industrial age began when James Watt produced first steam engine (1776) – Steam engine provided power to other areas – Machines improved • Steam/steel in ships, railroads, steam tractors • New power – electricity produced by generators • Diesel and gasoline engines
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History of Machine Tools • Progress continued slowly during first part of 20th century – Spurts during the two world wars
• Since 1950s, progress rapid • Now in space age – – – –
Atom harnessed: nuclear power Journey to moon and outer space Calculators, computers, robots commonplace Can mass produce parts to millionths of an inch
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Improved Production • Constant improvement made modern machine tools more accurate and efficient • Improved production and accuracy – – – –
Hydraulics Pneumatics Fluidics Electronic devices
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Common Machine Tools • Generally power-driven metal-cutting or forming machines used to shape metals – The removal of chips – Pressing, drawing, or shearing – Controlled electrical machining processes
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Machine Tool Capabilities • Holding and supporting the workpiece • Holding and supporting a cutting tool • Imparting a suitable movement (rotating or reciprocating) to the cutting tool or the work • Feeding the cutting tool or the work so that the desired cutting action and accuracy will be achieved
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Machine Tool Categories • Four broad categories – – – –
Chip-producing machines Non-chip-producing machines New-generation machines Multi-tasking machines
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Chip-producing Machine • Form metal to size and shape by cutting away unwanted sections • Generally alter shape of steel-produced products – Casting – Forging – Rolling
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Non-chip-producing Machines • Form metal to size and shape by pressing, drawing, punching, or shearing • Produce parts by compressing granular or powdered metallic materials
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New-Generation Machines • Perform operations that cannot be done on chip- or non-chip-producing machines • Use either electrical or chemical energy
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Multi-tasking Machines • Combined machining and turning center • Can produce virtually any shape part from rough to finish • Consists of turning center with two independent spindles and vertical machining center with rotary tool spindle • Combine Information Technology (IT) and Manufacturing Technology (MT)
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Machine Tool Performance • Metal-removal rate – Depends upon cutting speed, feed rate, and depth of cut
• Accuracy – How precisely machine can position cutting tool to given location once
• Repeatability – Ability of machine to position cutting tool consistently to any given position
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General Machine Shop Tools • Tools basic to production of metal components • Operations most commonly performed: turning, boring, threading, drilling, reaming, sawing, milling, filing, and grinding • Basic Machine tools – Drill press, engine lathe, power saw, milling machine and grinder
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Drill Press • • • •
First mechanical device developed Used primarily to produce round holes Function to grip and revolve cutting tool Common operations – Drilling, reaming, spot facing, countersinking, counterboring, and tapping
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Engine Lathe • Used to produce round work • Workpiece held and mounted on lathe spindle which is revolved against cutting tool • Common operations – Straight turning, tapering, facing, drilling, boring, reaming, and thread cutting
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Two Types of Metal Saw • Reciprocating cutoff saw – Used to cut work to length only
• Bandsaw – Horizontal
Material in vise and saw blade brought into contact with work
• Used to cut work to length
– Vertical • Used to cut work to length and shape Material on table and brought into contact with continuous-cutting saw blade
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Milling Machine • Two types: horizontal and vertical milling • Use one or more rotating milling cutters with single or multiple cutting edges • Workpiece fed into revolving cutter • Accessories allow wide variety of operations – Drilling, reaming, boring, counterboring and spot facing
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Grinder • Use abrasive cutting tool on workpiece – Bring to accurate size
– Produce high surface finish
• Surface of work brought into contact with revolving grinding wheel
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Common Types of Grinders • Surface – Used to produce flat, angular, or contoured surfaces
• Cylindrical – Used to produce internal and external diameters
• Cutter and Tool – Used to sharpen milling machine cutters
• Bench or Pedestal – Used for offhand grinding and sharpening
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Special Machine Tools • Designed to perform all operations necessary to produce single component • Include – – – –
Gear-generating machines Centerless, cam and thread grinders Turret lathes Automatic screw machines
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Computer Numerical Control Machines (CNC) • Brought tremendous changes • Computer control of machines has allowed speed of production and undreamed of accuracies – Operating commands executed with speed, accuracy, efficiency and reliability
• Replacing conventional machine tools operated by hand
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CNC Equivalent of Engine Lathe • Capable of machining round parts in one sixth time of skilled machinist • Two centers – Chucking • Designed to machine parts in a chuck (holding and driving device)
– Turning • Designed mainly for shaft-type workpieces supported by some type of tailstock center
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Machining Centers • CNC equivalent of milling machine – Can change cutting tools
• Two types of machining centers – Vertical • Used for flat parts where three-axis machining required
– Horizontal • Spindle in horizontal position • Allows parts to be machined on any side in one setup if equipped with indexing table
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Electrical Discharge Machines • Use controlled spark erosion process between cutting tool and workpiece to remove metal • Two most common EDM machines – Wire-cut • Uses traveling wire to cut internal and external shapes of workpiece
– Vertical ram (die sinking machine) • Feeds form tool down into workpiece
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Machining New Space-age Materials • Produce shapes which were difficult or impossible to produce by other methods • Four new machine tools – – – –
Electro-discharge machining Electochemical machining Electrolytic grinding Laser machining
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Robotics • One of fastest-growing areas of manufacturing industry • Numerical control applied to robots • Capable of handling materials and changing machine tool accessories easily and efficiently
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Lasers • Used increasingly for cutting and welding • Used in sensing devices for extremely accurate measuring and surveying • Used for many materials beyond metals
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Past Half Century Developments • Slow development until early 1930s • After 1932 automation introduced • Great Depression provided lull in production and time used to upgrade machines • AMT (Association for Manufacturing Technology) list of important developments in metalworking found in text starting on page 12
PowerPoint to accompany
Technology of Machine Tools 7th Edition
Krar • Gill • Smid
Careers in the Metalworking Industry Unit 2
McGraw-Hill
Copyright © 2011 by The McGraw-Hill Companies, Inc. All rights reserved
2-33
Objectives • The various types of jobs available in the metal-working industry • The type of work each job entails
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New Technologies • Tool that makes it possible to produce better quality goods at lower prices • Continually changing and improving • Doubling every three to five years • Training can make difference between success and failure • Industrial workers and students must prepare for continual education to survive
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Technology Curriculums • Imperative for educators to stay abreast of new improvements and manufacturing processes • Educators must continually introduce new material into curriculum • Old “time-proven” methods and processes have been outmoded
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Technology Courses
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Modular Training System • Consists of individual modules that can be readily incorporated into tech curriculum • Main areas of modular training system – – – – – – –
Conventional machining CNC machining CAD/CAM techniques Quality control Maintenance Automation Flexible manufacturing
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Apprenticeship Training • Apprentice employed to learn trade under guidance of skilled tradespeople • Joint agreement – Sponsoring apprentice company – Dept of Labor Federal Bureau of Apprenticeship – Trade union
• To qualify: completed high school program, good standing in math, science, writing skills and mechanical drawing • Wage scale increases periodically during program • Certificate granted upon completion, qualifies then for journeyman status in the trade
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Machine Operator • Classified as semiskilled tradespeople • Rating of A, B, C with A the more skilled • Class A skills – – – – –
Make necessary machine setups Adjust cutting tools Calculate cutting speeds and feeds Read and understand drawings Read and use precision measuring tools
• Jobs minimized with advancement of robots
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Maintenance Machinist • Needs combination of mechanical, rigging and carpentry skills • Apprenticeship usually ranges from 2-4 years – High school graduate – Good technical training
• General knowledge of electricity, carpentry, sheet metal and machine tool trade
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Machinist • Skilled workers who can efficiently operate all standard machine tools • Have thorough knowledge of metallurgy and heat treating • Have basic understanding of welding, hydraulics, electricity and pneumatics • Be familiar with computer technology
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Types Of Machine Shops • Maintenance shop – Generally makes and replaces parts for all types of setup and cutting tools and production machinery
• Production shop – Makes many types of identical machined parts, such as pulleys, shafts, bushings, motors, etc.
• Jobbing shop – Required to do variety of tasks (usually under contract to other companies)
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Job Classifications • Technician – Works at level between professional engineer and machinist – May assist engineer
• Technologist – Works at level between graduate engineer and technician – 3-4 year graduates from technical college • Physics, advanced math, chemistry, graphics, computer programming, business courses
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Job Classifications • Engineering technologist – Do many jobs normally performed by an engineer – Often employed in middle management
• Tool and Diemaker – Highly skilled craftsperson able to make different types of dies, molds, cutting tools, jigs, and fixtures – Serve an apprenticeship, have above-average mechanical ability, operate all standard machine tools
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CNC Machine Operator/Programmer • Duties vary from shop to shop • Skills include how to: – Visualize a CNC program – Understand machining processes and the sequence of operations – Make machine setups – Calculate speeds and feeds – Select cutting tools
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CNC Machine Programmer • Duties vary from shop to shop • Skills include how to: – All the skills of a CNC machine operator – Be skilled in print reading – Have a good knowledge of computer programming languages and procedures – Be able to visualize machining processes and operations
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Quality Control Inspector • Checks and examines machined parts to determine whether they meet specifications • Have technical or vocational education • Skills necessary – Understand and read mechanical drawings – Make basic mathematical calculations – Use micrometers, gages, comparators, and precision measuring instruments
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Instrument Makers • Highly skilled tool and diemakers working directly with scientists and engineers • Have more training than machinist or tool and diemaker • Must work to closer tolerances • Generally serve 4-5 years apprenticeship
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Professions • Many areas open to engineering graduate – Bachelor’s degree in engineering – Specialize in specific engineering discipline • Industrial, Metallurgical, Aerospace • Mechanical, Electrical, Electronics
• Technicians becoming more plentiful – High school diploma, plus 2 years higher ed – Usually trained in one area technology
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Trade Organizations • Help members stay abreast of changes • Implement new manufacturing technology in order to stay competitive in the world • Two major machine tool related organizations – AMT • Association for Manufacturing Technology
– SME • Society of Manufacturing Engineers
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Association for Manufacturing Technology (AMT) • Formerly the National Machine Tool Builders’ Association • Nonprofit trade association representing US • Supports extensive scholarship program for technical training • Provides machines, tools for young machinists to compete in VICA • Develops effective training procedures and textbooks
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Society of Manufacturing Engineers (SME) • International society dedicated to advancing manufacturing profession • Over 80,000 members throughout world • Sponsors ~300 student chapters with over 9000 members in community colleges and technical schools • Storehouse for up-to-date technological knowledge
