ch22metal cutting(for class)

2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMACHINING OPERATIONS AND MACHINE TOOLSTurning and Related OperationsDrilling and Related OperationsMillingMachining Centers and Turning CentersOther Machining OperationsHigh Speed Machining

2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMachiningA material removal process in which a sharp cutting tool is used to mechanically cut away material so that the desired part geometry remainsMost common application: to shape metal partsMost versatile of all manufacturing processes in its capability to produce a diversity of part geometries and geometric features with high precision and accuracyCasting can also produce a variety of shapes, but it lacks the precision and accuracy of machining


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eRotational - cylindrical or disklike shape Nonrotational (also called prismatic) - blocklike or platelikeFigure 22.1 Machined parts are classified as: (a) rotational, or (b) nonrotational, shown here by block and flat parts.Classification of Machined Parts


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMachining Operations and Part GeometryEach machining operation produces a characteristic part geometry due to two factors:Relative motions between tool and workpartGenerating part geometry determined by feed of cutting toolShape of the cutting toolForming part geometry is created by the shape of the cutting tool


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.2 Generating shape: (a) straight turning, (b) taper turning, (c) contour turning, (d) plain milling, (e) profile milling.Generating Shape


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.3 Forming to create shape: (a) form turning, (b) drilling, and (c) broaching.Forming to Create Shape


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.4 Combination of forming and generating to create shape: (a) thread cutting on a lathe, and (b) slot milling.Forming and Generating


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eTurningSingle point cutting tool removes material from a rotating workpiece to generate a cylinderPerformed on a machine tool called a latheVariations of turning performed on a lathe:FacingContour turningChamferingCutoffThreading


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.5 Turning operation.Turning


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eTurning OperationClose-up view of a turning operation on steel using a titanium nitride coated carbide cutting insert (photo courtesy of Kennametal Inc.)


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.6 (a) facingTool is fed radially inwardFacing


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eInstead of feeding tool parallel to axis of rotation, tool follows a contour that is other than straight, thus creating a contoured shapeFigure 22.6 (c) contour turning Contour Turning


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eCutting edge cuts an angle on the corner of the cylinder, forming a "chamfer" Figure 22.6 (e) chamferingChamfering


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eTool is fed radially into rotating work at some location to cut off end of partFigure 22.6 (f) cutoffCutoff


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/ePointed form tool is fed linearly across surface of rotating workpart parallel to axis of rotation at a large feed rate, thus creating threadsFigure 22.6 (g) threadingThreading


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.7 Diagram of an engine lathe, showing its principal componentsEngine Lathe


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMethods of Holding the Work in a LatheHolding the work between centersChuckColletFace plate


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eHolding the Work Between CentersFigure 22.8 (a) mounting the work between centers using a "dog


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eChuckFigure 22.8 (b) threejaw chuck


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eColletFigure 22.8 (c) collet


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFace PlateFigure 22.8 (d) face plate for noncylindrical workparts


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eTurret LatheTailstock replaced by turret that holds up to six toolsTools rapidly brought into action by indexing the turretTool post replaced by foursided turret to index four toolsApplications: high production work that requires a sequence of cuts on the part


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eChucking MachineUses chuck in its spindle to hold workpartNo tailstock, so parts cannot be mounted between centersCutting tool actions controlled automatically Operators job: to load and unload parts Applications: short, lightweight parts


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eBar MachineSimilar to chucking machine except collet replaces chuck, permitting long bar stock to be fed through headstockAt the end of the machining cycle, a cutoff operation separates the new partHighly automated (a.k.a. automatic bar machine)Applications: high production of rotational parts


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eAutomatic Screw MachineSame as automatic bar machine but smallerApplications: high production of screws and similar small hardware items


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMultiple Spindle Bar MachinesMore than one spindle, so multiple parts machined simultaneously by multiple toolsExample: six spindle automatic bar machine works on six parts at a time After each machining cycle, spindles (including collets and workbars) are indexed (rotated) to next position


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.9 (a) Part produced on a sixspindle automatic bar machine; and (b) sequence of operations to produce the part: (1) feed stock to stop, (2) turn main diameter, (3) form second diameter and spotface, (4) drill, (5) chamfer, and (6) cutoff.Multiple Spindle Bar Machine


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eBoring Difference between boring and turning:Boring is performed on the inside diameter of an existing holeTurning is performed on the outside diameter of an existing cylinderIn effect, boring is internal turning operationBoring machines Horizontal or vertical - refers to the orientation of the axis of rotation of machine spindle


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.12 A vertical boring mill for large, heavy workparts.Vertical Boring Mill


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eCreates a round hole in a workpart Compare to boring which can only enlarge an existing holeCutting tool called a drill or drill bit Machine tool: drill pressFigure 21.3 (b) drillingDrilling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eThroughholes - drill exits opposite side of workBlindholes does not exit work opposite sideFigure 22.13 Two hole types: (a) throughhole, and (b) blind hole.Through Holes vs. Blind Holes


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eUsed to slightly enlarge a hole, provide better tolerance on diameter, and improve surface finishFigure 22.14 Machining operations related to drilling: (a) reamingReaming


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eUsed to provide internal screw threads on an existing holeTool called a tapFigure 22.14 (b) tappingTapping


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eProvides a stepped hole, in which a larger diameter follows smaller diameter partially into the hole Figure 22.14 (c) counterboringCounterboring


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eUpright drill press stands on the floor

Bench drill similar but smaller and mounted on a table or benchFigure 22.15 Upright drill pressDrill Press


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eLarge drill press designed for large partsFigure 22.16 Radial drill press (photo courtesy of Willis Machinery and Tools).Radial Drill


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eWork Holding for Drill Presses Workpart in drilling can be clamped in any of the following:Vise - general purpose workholder with two jawsFixture - workholding device that is usually customdesigned for the particular workpart Drill jig similar to fixture but also provides a means of guiding the tool during drilling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMillingMachining operation in which work is fed past a rotating tool with multiple cutting edgesAxis of tool rotation is perpendicular to feedCreates a planar surfaceOther geometries possible either by cutter path or shape Other factors and terms:Interrupted cutting operationCutting tool called a milling cutter, cutting edges called "teeth" Machine tool called a milling machine


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 21.3 Two forms of milling: (a) peripheral milling, and (b) face milling. Two Forms of Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/ePeripheral Milling vs. Face MillingPeripheral millingCutter axis parallel to surface being machinedCutting edges on outside periphery of cutterFace millingCutter axis perpendicular to surface being milledCutting edges on both the end and outside periphery of the cutter


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eBasic form of peripheral milling in which the cutter width extends beyond the workpiece on both sidesFigure 22.18 (a) slab millingSlab Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eWidth of cutter is less than workpiece width, creating a slot in the workFigure 22.18 (b) slottingSlotting


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eCutter overhangs work on both sidesFigure 22.20 (a) conventional face millingConventional Face Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eHigh speed face milling using indexable inserts (photo courtesy of Kennametal Inc.).


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eCutter diameter is less than work width, so a slot is cut into partFigure 22.20 (c) end millingEnd Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eForm of end milling in which the outside periphery of a flat part is cutFigure 22.20 (d) profile millingProfile Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eAnother form of end milling used to mill shallow pockets into flat partsFigure 22.20 (e) pocket millingPocket Milling


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eBallnose cutter fed back and forth across work along a curvilinear path at close intervals to create a three dimensional surface form Figure 22.20 (f) surface contouringSurface Contouring


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.23 (a) horizontal knee-and-column milling machine.Horizontal Milling Machine


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.23 (b) vertical kneeandcolumn milling machineVertical Milling Machine


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMachining CentersHighly automated machine tool can perform multiple machining operations under CNC control in one setup with minimal human attentionTypical operations are milling and drillingThree, four, or five axesOther features: Automatic toolchanging Pallet shuttles Automatic workpart positioning


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.26 Universal machining center; highly automated, capable of multiple machining operations under computer control in one setup with minimal human attention (photo courtesy of Cincinnati Milacron).


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.27 CNC 4axis turning center (photo courtesy of Cincinnati Milacron); capable of turning and related operations, contour turning, and automatic tool indexing, all under computer control.


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMill-Turn Centers Highly automated machine tool that can perform turning, milling, and drilling operationsGeneral configuration of a turning centerCan position a cylindrical workpart at a specified angle so a rotating cutting tool (e.g., milling cutter) can machine features into outside surface of partConventional turning center cannot stop workpart at a defined angular position and does not include rotating tool spindles


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.28 Operation of a millturn center: (a) example part with turned, milled, and drilled surfaces; and (b) sequence of operations on a millturn center: (1) turn second diameter, (2) mill flat with part in programmed angular position, (3) drill hole with part in same programmed position, and (4) cutoff.Operation of Mill-Turn Center


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eSimilar operationsBoth use a single point cutting tool moved linearly relative to the workpartFigure 22.29 (a) Shaping, and (b) planing.Shaping and Planing


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eShaping and PlaningA straight, flat surface is created in both operationsInterrupted cutting Subjects tool to impact loading when entering workLow cutting speeds due to startandstop motion Typical tooling: single point high speed steel tools


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.30 Components of a shaper. Shaper


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.31 Open side planer.Planer


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eMoves a multiple tooth cutting tool linearly relative to work in direction of tool axisFigure 22.33 Broaching operation.Broaching


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eBroachingAdvantages: Good surface finishClose tolerancesVariety of work shapes possible Cutting tool called a broachOwing to complicated and often customshaped geometry, tooling is expensive


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/ePerformed on internal surface of a holeA starting hole must be present in the part to insert broach at beginning of strokeFigure 22.34 Work shapes that can be cut by internal broaching; crosshatching indicates the surfaces broached.Internal Broaching


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eSawingCuts narrow slit in work by a tool consisting of a series of narrowly spaced teethTool called a saw bladeTypical functions:Separate a workpart into two pieces Cut off unwanted portions of part


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.35 (a) power hacksaw linear reciprocating motion of hacksaw blade against work.Power Hacksaw


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.35 (b) bandsaw (vertical) linear continuous motion of bandsaw blade, which is in the form of an endless flexible loop with teeth on one edge.Band Saw


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eFigure 22.35 (c) circular saw rotating saw blade provides continuous motion of tool past workpart.Circular Saw


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eHigh Speed Machining (HSM)Cutting at speeds significantly higher than those used in conventional machining operations Persistent trend throughout history of machining is higher and higher cutting speedsAt present there is a renewed interest in HSM due to potential for faster production rates, shorter lead times, and reduced costs


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eHigh Speed MachiningConventional vs. high speed machining

Indexable tools (face mills)Work materialConventional speedHigh speedm/minft/minm/minft/minAluminum600+2000+3600+12,000+Cast iron, soft360120012004000Cast iron, ductile2508009003000Steel, alloy2107003601200Source: Kennametal Inc.


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eOther HSM Definitions DN RatioDN ratio = bearing bore diameter (mm) multiplied by maximum spindle speed (rev/min) For high speed machining, typical DN ratio is between 500,000 and 1,000,000Allows larger diameter bearings to fall within HSM range, even though they operate at lower rotational speeds than smaller bearings


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eOther HSM Definitions HP/RPM Ratiohp/rpm ratio = ratio of horsepower to maximum spindle speedConventional machine tools usually have a higher hp/rpm ratio than those equipped for HSMDividing line between conventional machining and HSM is around 0.005 hp/rpmThus, HSM includes 15 hp spindles that can rotate at 30,000 rpm (0.0005 hp/rpm)


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eOther HSM DefinitionsEmphasis on:Higher production ratesShorter lead times Rather than functions of spindle speedImportant non-cutting factors: Rapid traverse speeds Automatic tool changes


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eRequirements for High Speed MachiningSpecial bearings designed for high rpmHigh feed rate capability (e.g., 50 m/min)CNC motion controls with look-ahead features to avoid undershooting or overshooting tool pathBalanced cutting tools, toolholders, and spindles to minimize vibration Coolant delivery systems that provide higher pressures than conventional machiningChip control and removal systems to cope with much larger metal removal rates


2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/eHigh Speed Machining ApplicationsAircraft industry, machining of large airframe components from large aluminum blocksMuch metal removal, mostly by milling Multiple machining operations on aluminum to produce automotive, computer, and medical componentsQuick tool changes and tool path control important Die and mold industryFabricating complex geometries from hard materials


ch22metal cutting(for class)

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