Tool Design Cutting Tool Design

Nageswara Rao Posinasetti

Guidelines for Cutting tool Design

Š Rigidity Š Strength Š Weak links Š Force limitations Š Speed, feed and size Š Related force components Š Chip disposal Š Uneven motions Š Chatter January 31, 2008 Nageswara Rao Posinasetti 2

Basic tool angles (Tool Signature) Š Back rake angle Š Side rake angle Š End relief angle Š Side relief angle Š End cutting edge angle Š Side cutting edge angle Š Nose radius

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3 Selecting carbide Tools ŠEstablish the operating conditions ŠSelect the –Cemented carbide grade –Nose radius –Insert shape –Insert size –Insert thickness –Tool style –Rake angle –Shank size –Chip breaker

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Establish the operating conditions

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

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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, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 12 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

4 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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 13 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

To reduce cutting edge chipping

Š Increase the speed Š Decrease the feed and/or depth of cut Š Change to a tougher grade carbide insert Š Use a negative rake Š Hone the cutting edge before use Š Check the rigidity and tool overhang

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Select the cemented carbide grade

Straight carbides - Cast iron, Resistance to Tungsten carbide nonferrous and edge wear (WC) and cobalt nonmetallic binder materials

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5 Select the cemented carbide grade

Straight carbides - Cast iron, Resistance to Tungsten carbide nonferrous and edge wear (WC) and cobalt nonmetallic binder materials WC + Titanium Steels Resistance to carbide + Tantalum cratering carbide with cobalt binder Coated carbides

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Select the nose radius

Š Based on surface finish

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 21 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

7 Select the insert shape

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

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 23 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 26 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

Select the insert size

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

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9 Select the insert thickness

Š Gives the strength of the tool

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 29 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

Select the tool style

Š Based on the geometry of the operation to be performed.

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 31 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

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Select the rake angle

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FIGURE F-39 Side view of back rake angles.

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 39 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

13 Select the shank size

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 41 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 42 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

14 Select the chip breaker

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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.

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 44 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

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.)

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 45 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

15 Tool Holder Identification

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 47 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

Carbide Insert Identification

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

Richard R. Kibbe, JohnJanuary E. Neely, 31, 2008 Nageswara Rao Posinasetti 49 Roland O. Meyer, and Warren T. Copyright ©2002 by Pearson Education, Inc. White Upper Saddle River, New Jersey 07458 Machine Tool Practices, 7e All rights reserved.

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Multiple-Point Cutting Tools

Š Drilling Š Reaming Š Milling Š Gear cutting

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Power requirement for Drilling

Torque, M = 25,200 f 0.8 d 1.8 Thrust, T =57,500 f 0.8 d 0.8 + 625 d 2

Š d = drill diameter, in Š f = feed in/rev

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Power requirement for Reaming

2 ⎡ ⎛ d ⎞ ⎤ ⎢ 1 − ⎜ 1 ⎟ ⎥ 0.8 1.8 ⎢ ⎝ d ⎠ ⎥ M = 23,300 k f d 0.2 ⎢ ⎛ d ⎞ ⎥ ⎢1 + ⎜ 1 ⎟ ⎥ ⎣ ⎝ d ⎠ ⎦ ⎡ ⎛ d ⎞ ⎤ ⎢ 1 − ⎜ 1 ⎟ ⎥ 0.8 0.8 ⎢ ⎝ d ⎠ ⎥ T = 42,600 k f d 0.2 ⎢ ⎛ d ⎞ ⎥ ⎢ ⎜1 + 1 ⎟ ⎥ ⎣ ⎝ d ⎠ ⎦ d1 = reamer diameter, in. f = feed in/rev January 31, 2008 Nageswara Rao Posinasetti 59

Power M N Š Power in HP P = c 63,025 Š M = tool torque, in-lb Š N = speed, rpm Š Power in Watts = Hp * 746

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21 Milling Cutters

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25 26 Machining Power

Š Depends on the material removal rate Š Uses empirical equations developed based on experiments Š See Machinery’s Handbook – pp 1046 – 1055 (26th Edition)

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29 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)

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

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Drilling

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T = Thrust; lb or N M = Torque; in-lb or N.m N = Spindle rpm January 31, 2008 Nageswara Rao Posinasetti 93

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