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Introduction To Machine Tools

Introduction To Machine Tools

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Introduction To Machine Tools

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  1. Introduction To Machine Tools Section 1

  2. History of Machines Unit 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

  4. 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

  5. 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

  6. 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

  7. Improved Production • Constant improvement made modern machine tools more accurate and efficient • Improved production and accuracy • Hydraulics • Pneumatics • Fluidics • Electronic devices

  8. 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

  9. 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

  10. Machine Tool Categories • Four broad categories • Chip-producing machines • Non-chip-producing machines • New-generation machines • Multi-tasking machines

  11. Chip-producing Machine • Form metal to size and shape by cutting away unwanted sections • Generally alter shape of steel-produced products • Casting • Forging • Rolling

  12. 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

  13. New-Generation Machines • Perform operations that cannot be done on chip- or non-chip-producing machines • Use either electrical or chemical energy

  14. 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)

  15. 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

  16. 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

  17. 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

  18. 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

  19. Material in vise and saw blade brought into contact with work Material on table and brought into contact with continuous-cutting saw blade Two Types of Metal Saw • Reciprocating cutoff saw • Used to cut work to length only • Bandsaw • Horizontal • Used to cut work to length • Vertical • Used to cut work to length and shape

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. 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

  27. 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

  28. 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

  29. 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

  30. Lasers • Used increasingly for cutting and welding • Used in sensing devices for extremely accurate measuring and surveying • Used for many materials beyond metals

  31. 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 in text