Idea Transcript
Tool Design Cutting Tool Design
Nageswara Rao Posinasetti
Guidelines for Cutting tool Design
Rigidity Strength Weak links Force limitations Speed, feed and size Related force components Chip disposal Uneven motions Chatter
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Basic tool angles (Tool Signature) Back rake angle Side rake angle End relief angle Side relief angle End cutting edge angle Side cutting edge angle Nose radius January 31, 2008
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Selecting carbide Tools Establish the operating conditions Select the – Cemented carbide grade – Nose radius – Insert shape – Insert size – Insert thickness – Tool style – Rake angle – Shank size – Chip breaker January 31, 2008
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Establish the operating conditions Feed, speed and depth of cut greatly influence the machining performance. 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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
Machine Tool Practices, 7e
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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
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
Nageswara Rao Posinasetti
Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
To reduce cutting edge chipping Increase the speed Decrease the feed and/or depth of cut Change to a tougher grade carbide insert Use a negative rake Hone the cutting edge before use Check the rigidity and tool overhang January 31, 2008
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Select the cemented carbide grade Straight carbides Tungsten carbide (WC) and cobalt binder
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Cast iron, nonferrous and nonmetallic materials
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Resistance to edge wear
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Select the cemented carbide grade Straight carbides Tungsten carbide (WC) and cobalt binder WC + Titanium carbide + Tantalum carbide with cobalt binder Coated carbides
Cast iron, nonferrous and nonmetallic materials Steels
Resistance to edge wear
Resistance to cratering
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Select the nose radius Based on surface finish
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FIGURE F-34 Surface finish versus nose radius (copyright © General Electric Company).
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
Machine Tool Practices, 7e
2008
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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Select the insert shape Round – strong and large radius, good for higher feed rates Square – medium stronger 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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
Select the insert size Smallest size based on the depth of cut used Cutting 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
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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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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).
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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Select the rake angle
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FIGURE F-39
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
Machine Tool Practices, 7e
2008
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Side view of back rake angles.
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
Nageswara Rao Posinasetti
Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
FIGURE F-41 A boring bar with various interchangeable adjustable heads (Kennametal, Inc., Latrobe, PA).
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
Machine Tool Practices, 7e
2008
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
Machine Tool Practices, 7e
2008
Nageswara Rao Posinasetti
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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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, John E. Neely,31, January Roland O. Meyer, and Warren T. White
2008
Nageswara Rao Posinasetti
Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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.)
Richard R. Kibbe, John E. Neely,31, January Roland O. Meyer, and Warren T. White
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Machine Tool Practices, 7e
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Copyright ©2002 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.
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Multiple-Point Cutting Tools Drilling Reaming Milling 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 d = drill diameter, in f = feed in/rev
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Power requirement for Reaming 2 ⎡ ⎛d ⎞ ⎤ ⎢1− ⎜ 1⎟ ⎥ ⎝d⎠ ⎥ ⎢ 0.2 ⎢ ⎛ d1 ⎞ ⎥ ⎢1 + ⎜ ⎟ ⎥ ⎝d⎠ ⎦ ⎣
M = 23,300 k f 0.8 d 1.8
T = 42,600 k f 0.8 d 0.8
⎡ ⎛d ⎞ ⎤ ⎢ 1−⎜ 1⎟ ⎥ ⎝d⎠ ⎥ ⎢ 0.2 ⎢⎛ d ⎞ ⎥ ⎢ ⎜1 + 1 ⎟ ⎥ d⎠ ⎦ ⎣⎝
d1 = reamer diameter, in. f = feed in/rev January 31, 2008
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Power Power in HP
Pc =
M N 63,025
M = tool torque, in-lb N = speed, rpm Power in Watts = Hp * 746
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Milling Cutters
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Machining Power Depends on the material removal rate Uses empirical equations developed based on experiments See 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) January 31, 2008
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fm = feed rate, in/min or mm/min f = feed rate for turning, in/rev or mm/rev January 31, 2008
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Drilling
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T = Thrust; lb or N M = Torque; in-lb or N.m NJanuary = Spindle rpm 31, 2008
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