1
`
` PHISON 2004
`PNY Technologies, Inc. v. Phison Electronics Corp
` Case IPR2013-00472
`
`

`

`COPYRIGHT 1914. 1924, 1928, 1930, 1931, 1934, i936,1937,1939. 1940,1941, 1942.
`1943,1944,1945, 1946, 1948,1950, 1951,1952, 1953, 1954,1955, 1956, 1957,© l959,©
`1962, © 1964, © 1966, © 1968, © 1971, ©1974,©1975, ©1977,© 1979,© 1984, ©
`1988, © 1992, © 1996, © 1997, © 1998, © 2000 by Industrial Press Inc., New York, NY.
`
`Library of Congress Cataloging-in-Publication Data
`
`Oberg, Erik, 1881—1951
`Machinery's Handbook.
`2640 p.
`Includes index.
`
`1. Mechanical engineering—Handbook, manuals, etc.
`1. Jones, Franklin Day, 1879-1967
`11. Horton, Holbrook Lynedon, 1907—
`III. Ryffel, Henry H. I920-
`IV. Title.
`TJlS 1.0245
`2000
`621.8‘0212
`72—622276
`
`ISBN 0-831 1-2625—6 (Thumb Indexed 11.7 x 17.8 cm)
`ISBN 0-831 1-2635—3 (Thumb Indexed 17.8 x 25.4 cm)
`ISBN 0-831 1—2666-3 (CD—ROM)
`LC card number 72-622276
`
`INDUSTRIAL PRESS, INC.
`200 Madison Avenue
`
`New York. New York 100] 6-4078
`
`MACHINERY'S HANDBOOK
`26111 Edition
`
`First Printing
`
`Printed and bound in the United States ofAmerica by National Publishing Company. Philadelphia,
`Pa. All rights reserved. This book or parts thereof may not be reproduced, stored in a retrieval system,
`or transmitted in any form without permission of the publishers.
`
`2
`
`

`

`TABLE OF CONTENTS
`TOOLING AND TOOLMAKING
`
`__.._..___——
`
`CUTTING TOOLS
`FORE/[ING TOOLS
`Tool Contour
`753 Dovetail Forming Tools
`Terms and Definitions
`758
`Straight Forming Tools
`Relief Angles
`761
`Circular Forming Tools
`Rake Angles
`763
`Formulas
`Nose Radius
`764 Circular Tools
`Chipbreakers
`764
`Circular Cut-Off Tools
`Planing Tools
`765
`Constants for Diameters
`Indexable Inserts
`766
`Cor-rested Diameters
`Identification System
`770 Arrangement of Circular Tools
`Indexable 1353‘” T001 Holders ———'~_‘——
`Standard Shank Sizes
`MILLING CUTTERS
`Lem Symbols
`s 1
`tie
`f Millin Cutters
`771
`Indexabl e Insert Holders
`771 Nigbernog Teeth g
`Sintered Carbide Blanks
`772 Hand of Milling Cutters
`Standard Sizes for Carbide Blanks
`773
`Plain Milling Cutters
`Style A Carbide Tipped Tools
`774
`Side Milling Cutters
`Smgle’l’nmtv 5 '“tmd'ca’blde'
`775
`Staggered Teeth,T—Slot Milling
`Tipped Tools
`Cutters
`Style B Carbide Tipped Tools
`776 Metal slitting Saws
`Style C Carbide Tipped Tools
`776 Milling Cutler Terms
`Style D Carbide Tipped Tools
`773
`Shell Mills
`Style Er Calida TIPPEd T0015
`779 Multiple- and Two-Flute Single
`Standard Styles ER and EL
`End Helical End Mills
`Carbide T313964 T0015
`780 Regular, Long-, and Extra Long-
`Style F CarbideTipped Tools
`Length, Mills
`“0137056 Rad"
`731
`TwovFlute, High Helix, Regular»,
`To01 Angle Tolerances
`Long, and Extra Lontt-Lengtli,
`Style G, Carbide Tipped Tools
`Mills
`"
`782
`CEMENTED CARBIDES
`Roughing, Single-End End Mills
`—-—~—-—— 790
`Concave. Convex. and Corner,
`747
`Cemented Carbide
`Rounding Arbor-Type Cutters
`747
`Carbides and Carbonitrides
`Roller Chain Sprocket
`792
`748
`Properties of TungstenACarbideA
`Keys and Keyways
`794
`Based CuttingATool
`795 Woudruff Keyseat Cutters
`ISO Classifications of Hardmetals
`799
`SplineeShaft Milling Cutter
`Ceramics
`799 Cutter Grinding
`Superhard Materials
`800 Wheel Speeds and Feeds
`Machining Data
`800
`Clearance Angles
`Hardlnetal Tooling
`801
`Rake Angles for Milling Cutters
`Cutting Blades
`80]
`Eccentric Type Radial Relief
`804
`Indicator Drop Method
`806 Distance to Set Tooth
`
`744-
`744
`74-5
`745
`746
`746
`
`752
`752
`755
`756
`757
`757
`
`720
`
`3
`
`

`

`TABLE OF CONTENTS
`
`
`REAIWERS
`
`807 Hand Reamers
`808
`Irregular Tootli Spacing in
`Reamers
`808
`Threaded—end Hand Reamers
`808
`Fluted and Rose Chucking
`Reamers
`81] Vertical Adjustment of Tooth-rest
`S 12
`Reamer Difficulties
`813 Dimensions of Centers
`814
`Expansion chucking Reamers
`8 16 Hand Reamers
`817
`Expansion Hand Reamers
`818 Driving Slots and Lugs
`819
`Chueking Reamers
`822
`Shel] Reamers
`
`825
`Taper Pipe Reamers
`TWIST DRILLS AND
`COUNTERBORES
`
`827 Definitions of Twist Drill Terms
`828
`Types of Drill
`848
`British Standard Combined Drills
`843
`Split-Sleeve, Collet Type Drill
`Drivers
`849 Three and Four-Flute Straight
`Shank Core Drills
`850 Drill Drivers
`850
`British Standard Metric Twist
`Drills
`851 Gauge and Letter Sizes
`852 Morse Taper Shank Twist Drills
`853
`Tolerance on Diameter
`854
`Parallel Shank lobber Series
`Twist Drills
`856
`Stub Drills
`856
`Steels for Twist Drills
`856 Accuracy of Drilled Holes
`857
`Counterboring
`858
`Interchangeable Cutters
`858
`Three Piece Counterhores
`859
`Style Designations
`859
`Square Boring Tools
`859
`Sintered Carbide Boring Tools
`860
`Carbide—Tipped Square Boring
`Tools
`862
`Solid Carbide Round Boring
`Tools
`
`
`TWIST DRILLS AND
`
`COUNTERBORES
`(Cont)
`865
`Spade Drills and Drilling
`865
`Spade Drill Geometry
`867
`Spade Drilling
`869
`Feed Rates
`870
`Power Consumption
`
`87]
`Trepann'mg
`TAPS AND THREADING DIES
`872
`Types of Taps
`872 Definitions of Tap Terms
`876
`Fraction—Size Taps
`878 Machine Screw Taps
`879 Ground Thread Limits
`2380
`Taper Pipe Taps
`881
`Straight Pipe Taps
`883
`Straight Fluted Taps
`885
`Spiral-Pointed Taps
`890 ANSI Standard Taps
`89 1
`Pulley Taps
`891
`Spark Plug Taps
`893
`Spiral Pointed Ground Thread
`Taps
`Taper and Straight Pipe Taps
`894
`Thread Series Designations
`896
`Pitch Diameter Tolerance
`897
`Eccentricity Tolerances
`897
`S99 Acme Threads Taps
`900
`Acme and Square-Threaded Taps
`901
`Proportions
`901 Drill Hole Sizes
`902
`Screwing Taps for 180 Metric
`Threads
`905
`Tapping Square Threads
`STANDARD TAPERS
`
`906 Standard Tapers
`906 Morse Taper
`906 Brown & Sharpe Taper
`906
`Jarno Taper
`914
`British Standard Tapers
`915 Morse Taper Sleeves
`916
`Brown & Sharpe Taper Shank
`917
`Jarno Taper Shanks
`917 Machine Tool Spindles
`918
`Plug and Ring Gages
`919
`Jaeobs Tapers and Threads
`920
`Spindle Noses
`
`721
`
`4
`
`

`

`TABLE OF CONTENTS
`
`945
`
`947
`
`
`
`
`
` STANDARD TAPERS (Cont.) JIGS AND FIXTURES
`
`922
`Tool Shanks
`941 Jig Bushings
`923
`Draw-in Bolt Ends
`941 Materials
`924
`Spindle Nose
`941
`American National Standard
`
`925
`Twist Dn'iis and Centering Tools
`942 Head fiipe Press Fit Wearing
`B ushings
`Specifications for Press Fit
`,
`Wearing Bushings
`511p Type Renewable Wearing
`‘ Bushings
`_
`Fixed Type Renewable Wearing
`Bushings
`948 Headless Type Liner Bushings
`950
`Ludwig Mechamnn‘as
`951
`Jig Bushing‘Defimtions
`951
`J1g Plate Thickness
`951
`Jig Bushingr Designation System
`951
`Definition of Jig and Fixture
`951
`1}: Borers
`.
`952
`5134301133 Practm
`953
`Transfer Of Tolerances
`955
`Lengths of Chords
`956 Hole Coordinate Dimension
`FB‘FtOTS .
`>
`957
`Spacrng Otf the Cneumferences
`of Circles
`959 Hole Coordinate Dimension
`Factors
`971 C0116“
`,
`971
`Collets for Lathes, Mills,
`Grinders, and Fixtures
`
`W 945
`926
`The Broaehing Process
`926
`Types of Broaehes
`927
`Pitch of Breath Teeth
`928 Designing Data for Surface
`Brooches
`Bm'dChiug Pressure
`923
`929 Depth of Cut per Tooth
`930
`Face Angle or Rake
`930
`Clearance Angle
`930
`Land Width
`930 Depth of Breach Teeth
`930 Radius of Tooth Fillet
`930
`Total Length of Branch
`930
`Chip Breakers
`931
`Shear Angle
`931
`Types of Breathing Machines
`931
`Broaehing Difiicullies
`933 Tool Wein-
`3
`11.
`~
`-
`1;,
`33:
`15%;?ngéfigfilitfji; 1:001 Flanks
`936 Drlli Point Thinning
`937
`Sharpening Carbide Tools
`937
`Silicon Carbide Wheels
`938 Diamond Wheels
`938 Diamond Wheel Grit Sizes
`938 Diamond Wheel Grades
`938 Diamond Concentration
`939 Dry Versus Wet Grinding of
`Carbide Tools
`939
`Coolants for Carbide Tool
`Grinding
`Peripheral Versus Flat Side
`Grinding
`Lapping Carbide Tools
`Chip Breaker Grinding
`Summary of Miscellaneous Points
`
`939
`
`940
`940
`940
`
`722
`
`5
`
`

`

`CUTTING TOOLS
`
`CUTTJNG TOOLS
`
`723
`
`Tool Contour.—Tools for turning, planing, etc, are made in straight, bent, offset, and
`other forms to place the cutting edges in convenient positions for operating on differently
`located surfaces. The contour or shape of the cutting edge may also be varied to suit differ
`ent classes ofwork. Tool shapes, however, are not only relatedtn the kindofoperation. but,
`in roughing tools particularly, the content may have a decided effect upon the cutting effi-
`ciency of the tool. To illustrate, an increase in the side cutting—edge angle of a roughing
`tool, or in the nose radius, tends to permit higher cutting speeds because the chip will be
`thinner for a given feed rate. Such changes, however, may result in chattering or vibrations
`unless the work and the machine are rigid; hence, the most desirable contour may be a com-
`promise between the ideal form and one that is needed to meet practical requirements.
`Terms and Definitions—The terms and definitions relating to singleepoint tools vary
`somewhat in different plants, but the foilowLug are in general use.
`
`
`
`Side Rake
`Angle
`
`End Cutting
`Edge Angle
`
`Bank Rake
`
`Angle
`
`'nml Point or
`
`Nose Radius
`
`Side Relief
`’
`Angle
`
`f i
`.
`A
`End Relief
`Angle
`
`Side Cutting
`Edge Angle
`
`Figi l.Te1ms Applied to Single»poi.ttt Turning Tools
`Single—point Tool: This tennis applied to tools for turning, planing, boring, etc‘, which
`have a cutting edge atone end. This cutting edge may be formed on one end of a solid piece
`of steel, or the cutting part of the tool may consist of an insert or tip which is held to the
`body ofthe tool by brazing, welding, or mechanical means.
`Shank: The shanlt is the main body of the tool. lfthe tool is an inserted cutter type, the
`shank supports the cutter or hit. [See diagram, Fig. 1‘)
`Nose: A general term sometimes used to designate the cutting end but usualiy relating
`more particuiarly to the rounded tip of the cutting end.
`Face: The surface against which the chips bear, as they are severed in turning or planing
`operations, is called the face.
`Flank: The flank is that and surface adjacent to the cutting edge and below it when the
`tool is in a horizontal position as for turning.
`Base: The base is the surface of the mol shank that bears against the supporting tool,
`holder orblock.
`Side Cutting Edge: The side cutting edge is the cutting edge on the side ofthe tool. Tools
`such as shown in Fig. 1 do the bulk of the cutting with this cutting edge and are, therefore,
`sometimes called side cutting edge tools.
`End Cutting Edge: The end cutting edge is the cutting edge at the end of the tool.
`On side cutting edge tools, the end cutting edge canbe used for light plunging and facing
`cuts. Cutoff tools and similar tools have only one cutting edge located on the end. These
`
`6
`
`

`

`724
`
`CUTTING TOOLS
`
`tools and other tools that are intended to cut primarily with the end cutting edge are some-
`times called end cutting edge tools.
`Rake: A metalwcutling tool is said to have rake when the tool face or Surface against
`which the chips bear as they are being severed, is inclined for the purpose ofeither increas—
`ing ordiminishing the keenncss or bluntness ofthe edge. The magnitude ofthe take is most
`conveniently measured by two angles called the back rake angle and the side rake angle.
`The tool shown in Fig. 1 has rake. If the face of the tool did not incline but was parallel to
`the base, there would he no rake; the rake angles wouldbe zero.
`Positive Rake: If the inclination of the tool face is such as to make the cutting edge
`keener or more acute than w hen the rake angle is zero. the rake angle is defined as positive.
`Negative Rake: if the inclination of the tool face makes the cutting edge less keen or
`more bluntthan when the ralce angle is zero, the take is defined as negative.
`Back Rake: The back rake is the inclination of the face toward or away from the end or
`the end cutting edge of the tool. When the inclination is away from the and cutting edge, as
`shown in Fig. l, the back rake is positive, 1f the inclination is downward toward the end
`cutting edge the hack rake is negative.
`Side Rake: The side rake is the inclination of the face toward or away from the side cut-
`ting edge. When the inclination is away from the side cutting edge, as shown in Fig. l . the
`side rake is positive. If the inclination is toward the side cutting edge the side rake is nega
`tive.
`Relief: The flanks below the side cutting edge and the end cutting edge must be relieved
`to allow these culting edges to penetrate into the workpiece when taking a cut. If the flanks
`are not provided wi lh relief, the cutting edges will rub against the workpiece and be unable
`to penetrate in order to form the chip. Relief is also provided below the nose of the tool to
`allow it to penetrate into the workpiece. The relief at the nose is Usually a blend of the side
`relief and the end relief.
`End ReliefAngle: The end relief angle is a measure of the relief below the end cutting
`edge.
`Side ReliefAngle: The side relief angle is a measure of the relief below the side cutting
`edge,
`Back Rake Angle: The back rake angle is a measure of the backrake. It is measured in a
`plane that passes through the side cutting edge and is perpendicular to the base. Thus, the
`back rake angle can be defined by measuring the inclination of the side cutting edge with
`respect to a line or plane that is parallel to the base. The back rake angle may be positive,
`negative, or zero depending upon the magnitude and direction ofthe backrake.
`Side Rake Angle: The side rake angle is a measure of the side rake. This angle is always
`measured in a plane that is perpendicular to the side cutting edge and perpendicular to the
`base. Thus, the side rake angle is the angle of inclination of the face perpendicular to the
`side cutting edge with reference to a line or a plane that is parallel to the hase.
`End Cutting Edge Angle: The end cutting edge angle is the angle made by the end cutting
`edge with respect to a plane perpendicular to the axis of the tool shank, It is provided to
`allow the end cutting edge to clear the finish machined surface on the workpiece
`Side Cutting Edge Angle: The side cutting edge angle is the angle made by the side cut
`ting edge and a plane that is parallel to the side of the shank.
`Nose Radius: The nose radius is theradius ofthe nose ofthe tool. The performance ofthe
`tool, in part. is influenced by nose radius so that it must be carefully controlled.
`Lead Angle: The lead angle, shown in Fig. 2, is not ground on the tool. it is a tool setting
`angle which has a great influence on the performance ofthe tool. The lead angle isbounded
`by the side cutting edge and a plane perpendicular to the workpiece surface when the tool
`is in posio'on to cut; or, more exactly, the lead angle is the angle between the side cutting
`edge and a plane perpendicular to the direction ofthe feed travel.
`
`7
`
`

`

`CUTTING TOOLS
`
`725
`
`Lead Angle
`
`Lent] Angle Equal
`to side Cutting Angie
`
`Side Cutting
`Edge Angle
`
`Fig. 2. Lead Angle on Single-point Turning Tool
`Solid Tool: A solid tool is a cutting tool made from one piece of tool material.
`Brazed Tool: A brazed tool is a cutting tool having a blank of cuttin34001 material per-
`manentiy brazed to a steel shank.
`Blank: A blank is an unground piece of cuttingvtool material from which a brazed tool is
`made.
`Too! Bit: A tool bit is a relatively small cutting tool that is clamped in a holder in such a
`way that it can readily be removed and replaced. It is intended priman'ly to be Ieground
`when dull and uotindexed.
`TaobbitBlank' The toolabit blank is an ungruund piece of cutting—tool material from
`which a tool bit can be made by grinding. It is available in standard sizes and shapes.
`Toolkit Holder: Usually made from forged steel, the tool-bit holder is used to hold the
`tool bit, to act as an extended shank for the tool bit, and to provide a means for cl amping in
`the tool post.
`Straight-shank Tool—bit Holder: A straightshauk tool—bit holder has a straight shank
`when Viewed from the top. The axis ofthe mo] bit is held parallel to the axis of the shank.
`Ofsez-sfmuk Tool-bit Holder: An offsekshauk tool—bit holder has the shank bent to the
`right or left, as seen in Fig. 3. The axis ofthe tool bit is held at an angle with respect to the
`axis ofthe shank.
`Side cutting Tool: A side cutting tool has its major cutting edge on the side ofthe cutting
`part of the tool. The major cutting edge may be parallel or at an angle with respect to the
`axis of the tool.
`Indexnble Inserts: An indexable insert is a relatively small piece of cutting-tool material
`that is geometrically shaped to have two or several cutting edges that are used until dull.
`The insert is then indexed on the holder to apply a sharp cutting edge. When all the cutting
`edges have been dulled, the insert is discarded. The insert is held in a pocket or against
`other locating surfaces on an indexahle insert holder by means of a mechanical clamping
`device that can be tightened or loosened easily.
`Indexuble Insert Holder: Made of steal, an indexable insert holder is used to hold index—
`able inserts. It is equipped with a mechanical clamping device that holds the inserts firmly
`in a pocket or against other sealing surfaces.
`Straight-shank (tidexoble Insert Holder: A straight-shank indexable insert tool-holder
`is essentially straight when viewed from the top, although the cutting edge of the insert
`may be oriented parallel, or at an angle to, the axis of the holder.
`Omet-sfzauklndemble Insert Holder: An offsetshank indexable insert holder has the
`head end, or the and containing the insertpocket, offset to the right or left, as shown in H g.
`3.
`
`8
`
`

`

`726
`
`CUTTING TOOLS
`
`{it}
`
`Fig 3. Top: Right-hand Offset-shank, Tndexable Inscrtl {older
`Bottom: Right-hand Offsct-shankTool-hit Holder
`End cutting Tool: An end cutting tool has its major cutting edge on the end ofthe cutting
`part of the tool, The major cutting edge may he perpendicular or at an angle, with respect to
`the axis of the tool.
`Curved Curling-Edge Tool: A curved cutting—edge tool has a continuously variable side
`cutting edge angle. The cutting edge is usually in the form of a smooth, continuous curve
`along its entire length, or along a large portion of its length.
`Righrihund Tout.- A right-hand tool has the major, or working, cutting edge on the right-
`hand side when viewed from the cutting end with the face up. As used in a lathe, such a tool
`is usually fed into the work from l'lght to left, when viewed from the shank end.
`Left-hand Tool: A left-hand tool has the major or working cutting edge on the left-hand
`side when viewed from the cutting and with the face up. As used in a lathe, the tool is usu-
`ally fed into the work from left to riglit, when viewed from the shank end.
`NeutraHmnd Tool: A neutral—hand tool is a tool to out either left to right or right to left;
`or the cut may heparallel to the axis of the shank as when plunge cutting.
`Chipbreaker: A groove formed in or on a shoulder on the face of a turning tool back of
`the cutting edge to break up the chips and prevent the formation of long,continuons chips
`which would be dangerous to the operator and a] so bulky and cumbersome to handle. A
`chipbreaker ofthe shoulder type may be formed directly on the tool face or it may consist
`of a separate piece that is held either by brazing or by clumping.
`ReliefAugles.-«-The end reliefangle and the side reliefang] e on singleipoint cutting tools
`are usually. though not invariably, made equal to each other. The relief angle under the
`nose of the tool is a blend ofthe side and and relief angles.
`The size of the relief angles has a pronounced effect on the performance of the cutting
`tool, If the relief angles are too large, the cutting edge will be weakened and in danger of
`breaking when a heavy cutting load is placed on it by a hard and tough material. 0n finish
`cuts, rapid wear of the cutting edge may cause problems with size control on the part,
`Reliefangles that are too small will cause the rate ofwear on the flank ofthe tool below the
`cutting edge to increase, thereby significantly reducing the tool life, in general, when cut-
`ting hard and tough materials, the relief angles should be 6 to 8 degrees for high-speed steel
`tools and 5 to 7 degrees for carbide tools. For medium steels, mild steels, cast iron, and
`other average work the recommended values of the relief angles are 8 to l2 degrees for
`highrspced steel tools and 5 to 10 degrees for carbides. Ductile materials having a rela-
`tively low modulus of elasticity should be cut using larger relief angles. For example, the
`reliefangles recommended for turning copper, brass, bronze, aluminum, ferritic malleable
`
`9
`
`

`

`CUTTING TOOLS
`
`727
`
`iron, and similar metals are 12 to 16 degrees for high—speed steel tools and 8 to 14 degrees
`for carbides.
`Larger relief angles generally tend to produce a better finish on the finish machined sur4
`face because less surface of the worn flank ofthe tool rubs against the workpiece. For this
`reason. single-point thread—cutting tools should be provided with relief angles that are as
`large as circumstances will permit. Problems encountered when machining stainless steel
`may be overcome by increasing the size of the relief angle. The relief angles used should
`never be smaller than necessary.
`Rake Angles.—Machinability tests have confirmed that when the rake angle along which
`the chip slides, called the true rake angle, is made larger in the positive direction, the cut—
`ting force and the cutting temperature will decrease. Also, the tool life for a given cutting
`Speed will increase with increases in the true ralte angle up to an optimum value, after
`which it will decrease again. For turning tools which cut primarily with the side cutting
`edge, the true rake angle corresponds rather closely with the side rake angle except when
`taking shallow cuts. Increasing the side rake angle in the positive direction lowers the cut—
`ting force and the cutting temperature, while at the same time it resuits in a longer tool life
`or a higher permissible cutting speed up to an optimum value of the side rake angle. After
`the optimum value is exceeded, the cutting force and the cutting temperature will continue
`to drop; however, the tool life and the permissible cutting speed will decrease.
`As an approximation, the magnitude of the cutting force will decrease about one per cent
`per degree increase in the side rake angle. While not exact, this rule of thumb does corre-
`spond approximately to test results and can be used to make rough estimates. Of course, the
`cutting force also increases about one per cent per degree decrease in the side rake angle.
`The limiting value of the side rake angle for optimum tool life or cutting speed depends
`upon the work material and the cutting tool material. In general. lower values can he used
`for hard and tough work materials. Cemented carbides are harder and more brittle than
`highespeed steel; therefore. the rake angles usually used for cemented carbides are less
`positive Ihanfor high-speed steel,
`Negative rake angles cause the face ofthe tool to slope in the opposite direction from pos-
`itive rake angles and. as might be expected, they have an opposite effect. For side cutting
`edge tools, increasing the side rake angiein a negative direction wilt rcsultin an increase in
`the cutting force and an increase in the cutting temperature of approximately one per cent
`per degree change in rake angle. For example, if the side rake angle is changed from 5
`degrees positive to 5 degrees negative, the cutting force will be about ll) per cent larger.
`Usually the tool life will also decrease when negative side rake angles are used, although
`the tool life will sometimes increase when the negative rake angle is not too large and when
`a fast cutting speed is used.
`Negative siderake angles are usually used in combination with negative back rake angles
`on singleepoint cutting tools. The negative rake angles strengthen the cutting edges
`enabling them to sustain heavier cutting loads and shock loads. They are recommended for
`turning very hard materials and for heavy interrupted cuts. There is also an economic
`advantage in favor of using negative rake indexable inserts and tool holders inasmuch as
`the cutting edges provided on both the top and bottom ofthe insert can be used.
`0n turning tools that cut primarily with the side cutting edge, the effect of the back ralce
`angle alone is much less than the effect of the side rake angle although the direction of the
`change in cutting force, cutting temperature, and tool life is the same. The effect that the
`backrake angle has can be ignored unless, ofcourse, extremely large changes in this angle
`are made. A positive back rake angle does improve the performance ofthe nose ofthe tool
`somewhat and is helpful in taking light finishing cuts. A negative baCkrake angle strength-
`ens the nose ofthe tool and is helpful when interrupted cuts are taken, The back rake angle
`has a very significant effect on the performance of and cutting edge tools, such as cutzoff
`tools. For these tools, the effect of the back rake angle is very similarto the effect of the side
`rake angle on side cutting edge tools.
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`Side Cutting Edge and Lead Angles—These angles are considered together because
`the side cutting edge angle is usually designed to provide the desired lead angle when the
`too] is being used. The side cutting edge angle and the lead angle will be equal when the
`shank of the cutting tool is positioned perpendicular to the workpiece, or, more correctly,
`perpendicular to the direction of the feed. When the shank is not perpendicular, the lead
`angle is determined by the side cutting edge and an imaginary line perpendicular to the
`feed direction.
`The flow of the chips over the face of the tool is approximately perpendicular to the side
`cutting edge except when shallow cuts are taken. The thickness of the undeformed chip is
`measured perpendicular to the side cutting edge. As the lead angle is increased. the iength
`of chip in contact with the side cutting edge is increased, and the chip will become longer
`and thinner. This effect is the same as increasing the depth of cut and decreasing the feed,
`although the actual depth of cut and feed remain the same and the same amount of metal is
`removed The effect of lengthening and thinning the chip by increasing the lead angle is
`very beneficial as it increases the tool life for a given cutting speed or that speed can be
`increased. increasing the cutting speed while the feed and the tool life remain the same
`leads to faster production.
`However, an adverse effect must be considered. Chatter can be caused by a cutting edge
`that is oriented at a high lead angle when turning and sometimes, when turning long and
`slender shafts, even a small lead angle can cause chatter. In fact, an unsuitable lead angle of
`the side cutting edge is one of the principal causes of chatter. When chatter occurs, often
`simply reducing the lead angle wi ll cure it. Sometimes, very long and slender shafts can be
`turned successfully with a tool having a zero degree lead angle (and having a small nose
`radius). Boring bars, being usually somewhat long and slender, are also susceptible to
`chatterifa large lead angle is used. The lead angle for boring bars shouldhe kept small, and
`for very long and slenderboring bars a zero degree lead angle is recommended. It is impos—
`sible to provide a rule that will determine when chatter caused by a lead angle will occur
`and when it will not. In making a judgment, the first consideration is the length to diameter
`ratio of the part to be turned, or of the boring bar. Then the method of holding the work—
`piece mustbe considered # a part that is firmly held is less apt to chatter. Finally, the over
`all condition and rigidity of the machine must be considered because they may he the real
`cause of chatter.
`Although chatter can be a problem, the advantages gainedfrom high lead angles are such
`that the lead angle should be as large as possible at all times.
`End Cutting Edge Angle—The size of the end cutting edge angle is important whentool
`wearby crater-111g occurs. Frequently, the crater Wi ll enlarge until itbreaks through the end
`cutting edge just behind the nose, and tool failure follows shortly. Reducing the size of the
`end cutting edge angle tends to delay the time ofcrater breakthrough.When cratering takes
`place, the recommended cnd cutting edge angle is S to 15 degrees. If there is no cratering,
`the angle can be made larger. Larger end cutfing edge angles may be required to enable
`profile turning tools to plunge into the work without interference from the and cutting
`edge.
`Nose Radiust—-The tool nose is a very critical part of the cutting edge since it cuts the fin-
`ished surface on the workpiece. Ifthe nose is made to a sharp point, the finish machined
`surface will usually be unacceptable and the life of the tool will be short. Thus, a nose
`radius is required to obtain an acceptable surface finish and tool life. The surface finish
`obtained is determined by the feed rate and by the nose radius if other factors such as the
`work material, the cutting speed, and eutting fluids are not considered. A large nose radius
`will give a better surface finish and will permit a faster feed rate to he used.
`Machinability tests have demonstrated that increasing the nose radius will also improve
`the tool life or allow a faster cutting speed to he used. For example, high-speed steel tools
`were used to turn an alloy steel in one series of tests where complete or catastrophic tool
`failure was used as a criterion for the end oftool life. The cutting speed for a 60—minute tool
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`life was found to be 125 [pm when the nose radius was 146inch and 160 fpin when the nose
`radius was Zinch.
`A very large nose radius can often be used but a limit is sometimes imposed because the
`tendency for chatter to occur is increased as the nose radius is made larger. A nose radius
`that is too large can cause chatter and when it does, a smaller nose radius must he used on
`the tool. ltis alway 3 good practice to make the nose radius as large as is compatible with the
`operation being performed.
`Chipbreakers.—-Many steel turning tools are equipped with chipbrealdng devices to pre-
`vent the formation of long continuous chips in connection with the taming of steel at the
`high speeds made possible by high-speed steel and especially cemented carbide tools.
`Long steel chips are dangerous to the operator, and cumbersome to handle. and they may
`twist around the tool and cause damage. Broken chips not only occupy less space, but per,
`mit a better flow ofcoolant to the cutting edge. S everal different forms of chipbreakers are
`ii Eustrated in Fig. 4.
`Angular Shoulder Type: The angular shoulder type shown atA is one of the commonly
`used forms. As the enlarged sectional View shows, the chipbreaking shoulder is located
`backofthe cutting edge. The angle a between the shoulder and cutting edge may vary from
`6 to 15 degrees or more. 8 degees being a fair average. The ideal angle, width W and depth
`G. depend upon the speed and feed, the depth of cut, and the material. As a general rule.
`width W. at the end of the tool, varies from 3/32to 7(flinch, and the depth G may range from
`14,410 Vie inch. The shoulder radius equals depth G. H the tool has a large nose radius. the
`corner of the shoulder at the nose end may be beveled off. as illustrated at B. to preveut it
`from coming into contact with the work. The width K for type B should equal approxi-
`mately 1.5 times the nose radius.
`Parallfl Shoulder Type.- Diagram C shows a design with a chipbreaking shoulder that is
`paraflel with the cutting edge. With this form. the chips are likely to come off in short
`curled sections. The parallel form may also be applied to straight tools which do not have a
`side cuttingeedge angle. The tendency with this parallel shoulder form is to force the chips
`against the work and damage it.
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`Fig. 4. Different Forms ofChipbreakers for TurningTuuls
`Groove Type: This type (diagram D) has a groove in the face of the tool produced by
`grinding. Between the groove and the cutting edge. there is a land L. Under ideal condi—
`tions, this width L, the groove width W, and the groove depth G. would be varied to suit the
`feed, depdi of cut and material. For average use, L is about J(flinch; G. 142mph; and W, 1/16
`inch. There are differences ofopinion concerning the relative merits ofthe groove type and
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`the shoulder type. Both types have proved satisfactory when properly proportioned for a
`given class of work.
`Chipbreakerfor Light Cutst Diagram E illustrates a form of chipbreaker that is some—
`times used ontools for finishing cuts having a maximum depth of about I(flinch. This chip-
`breaker is a shoulder type having an angle of45 degrees and a maximum width of about 1/16
`inch, It is important in grinding all chipbreakers to give the chipebearing surfaces afrnefin—
`ish, such as wouldbe obtained by honing. This finish greatly increases the life of the tool.
`Planing