Mfg Tooling -04 Cutting tool designrao/Mfg Tooling -04 Cutting tool design.pdf · 1 Tool Design Cutting Tool Design Nageswara Rao Posinasetti January 31, 2008 Nageswara Rao Posinasetti

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Tool DesignCutting Tool Design

Nageswara Rao Posinasetti

January 31, 2008 Nageswara Rao Posinasetti 2

Guidelines for Cutting tool Design

RigidityStrengthWeak linksForce limitationsSpeed, feed and sizeRelated force componentsChip disposalUneven motionsChatter


Basic tool angles (Tool Signature)

Back rake angleSide rake angleEnd relief angleSide relief angleEnd cutting edge angleSide cutting edge angleNose radius

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Selecting carbide ToolsEstablish the operating conditionsSelect the

–Cemented carbide grade–Nose radius–Insert shape–Insert size–Insert thickness–Tool style–Rake angle–Shank size–Chip breaker


Establish the operating conditions

Feed, speed and depth of cut greatly influence the machining performance.Also lead angle affects the performance


FIGURE F-27 The difference in style A and style D holders for depth of cut and cutting edge engagement length (copyright ©General Electric Company).

Richard R. Kibbe, John E. Neely, Roland O. Meyer, and Warren T. WhiteMachine Tool Practices, 7e

Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

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FIGURE F-28 Large, well-formed chips were produced by this tool with built-in chip breaker (Kennametal, Inc., Latrobe, PA).




Large depth of cut


To reduce cutting edge chipping

Increase the speedDecrease the feed and/or depth of cutChange to a tougher grade carbide insertUse a negative rake Hone the cutting edge before useCheck the rigidity and tool overhang


Select the cemented carbide grade

Resistance to edge wear

Cast iron, nonferrous and nonmetallic materials

Straight carbides -Tungsten carbide (WC) and cobalt binder

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Select the cemented carbide grade

Coated carbides

Resistance to cratering

SteelsWC + Titanium carbide + Tantalum carbide with cobalt binder

Resistance to edge wear

Cast iron, nonferrous and nonmetallic materials

Straight carbides -Tungsten carbide (WC) and cobalt binder



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Select the nose radius

Based on surface finish


FIGURE F-34 Surface finish versus nose radius (copyright © General Electric Company).




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Select the insert shape

Round – strong and large radius, good for higher feed ratesSquare – medium strongerTraingular – least stronger, less number of cutting edges, but more versatile in use


FIGURE F-35 Insert shapes for various applications (Kennametal, Inc., Latrobe, PA)





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FIGURE F-36 A 38-degree triangular insert used for a tracing operation (copyright © General Electric Company).





Select the insert size

Smallest size based on the depth of cut usedCutting edge should be 1.5 times that of the length of cutting edge engagement.

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Select the insert thickness

Gives the strength of the tool


FIGURE F-37 Insert thickness as determined by length of cutting edge engagement and feed rate (copyright © General Electric Company).





Select the tool style

Based on the geometry of the operation to be performed.

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FIGURE F-38 Several of the many tool styles available (Kennametal, Inc., Latrobe, PA).






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Select the rake angle


FIGURE F-39 Side view of back rake angles.




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Select the shank size


FIGURE F-40 Determining shank size according to depth of cut, feed rate, and tool overhang (copyright © General Electric Company).





FIGURE F-41 A boring bar with various interchangeable adjustable heads (Kennametal, Inc., Latrobe, PA).




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Select the chip breaker


FIGURE F-42 Chip breakers used are the adjustable chip deflator (center) with a straight insert and the type with the built-in chip control groove.





FIGURE F-43(b, c) (a) Negative rake two-sided Kenloc inserts; *Maximum D.O.C. and feed rates (ipr) are limited by the insert thickness and cutting edge length. Application ranges are for AISI 1045 steel at 180 to 220 BHN (Kennametal, Inc., Latrobe, PA.)




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Tool Holder Identification


FIGURE F-44 ASA tool identification system (Tool Application Handbook; data courtesy of Kennametal, Inc., Latrobe, PA, 1973.)





Carbide Insert Identification

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FIGURE F-45 ASA carbide insert identification (Tool Application Handbook; data courtesy of Kennametal, Inc., Latrobe, PA, 1973.)






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Multiple-Point Cutting Tools

DrillingReamingMillingGear cutting

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Power requirement for Drilling

d = drill diameter, inf = feed in/rev

8.18.0200,25, dfMTorque =28.08.0 625500,57, ddfTThrust +=


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Power requirement for Reaming

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

⎟⎠⎞

⎜⎝⎛+

⎟⎠⎞

⎜⎝⎛−

= 2.01

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8.18.0

1

1300,23

dddd

dfkM

⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢

⎣

⎡

⎟⎠⎞

⎜⎝⎛ +

⎟⎠⎞

⎜⎝⎛−

= 2.01

1

8.08.0

1

1600,42

dddd

dfkT

d1 = reamer diameter, in.

f = feed in/rev


Power

Power in HP

M = tool torque, in-lbN = speed, rpmPower in Watts = Hp * 746

025,63NMPc =

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Milling Cutters



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Machining Power

Depends on the material removal rateUses empirical equations developed based on experimentsSee Machinery’s Handbook– pp 1046 – 1055 (26th Edition)


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Pc = power at the cutting tool

Pm = power at the motor

Kp = power constant (see tab 24, 25 and 30)

Q = metal removal rate (tab 29)


fm = feed rate, in/min or mm/min

f = feed rate for turning, in/rev or mm/rev


Drilling

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T = Thrust; lb or N

M = Torque; in-lb or N.m

N = Spindle rpm

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Documents

Mfg Tooling -04 Cutting tool designrao/Mfg Tooling -04 Cutting tool design.pdf · 1 Tool Design Cutting Tool Design Nageswara Rao Posinasetti January 31, 2008 Nageswara Rao Posinasetti