Although almost any book and/or text on metal cutting, cutting tool design, and 9 ~4 v& @/ ]4 Q w/ t" F
manufacturing process discusses to a certain extent the tool geometry, the body of . S( E6 w" _. B4 }4 F; D
knowledge on the subject is scattered and confusing. Moreover, there is no clear
! Q3 ~7 q5 H0 I# _objective(s) set in the selection of the tool geometry parameters so that an answer $ T0 _4 y- e8 T6 I: A
to a simple question about optimal tool geometry cannot be found in the literature " }) X. Q# x' f9 w7 P
on the subject. This is because a criterion (criteria) of optimization is not clear, on ( N* u) Z3 v- Q& W7 B9 L1 U) @
one hand, and because the role of cutting tool geometry in machining process " C$ R! r( z, M& `
optimization has never been studied systematically, on the other. As a result, many `% B! B& S! x' R0 l8 {- _$ f7 H; x
practical tool/process designers are forced to use extremely vague ranges of tool
6 d7 s+ W$ b: m% \% F9 @- I0 [. }geometry parameters provided by handbooks. Being at least 20+ years outdated, 2 I6 c: B% q: {9 j
these data do not account for any particularities of a machining operation including : W" @- I0 `9 {6 v6 ^4 ]
a particular grade of tool material, the condition of the machine used, the cutting : M+ G3 D) G3 D" R
fluid, properties and metallurgical condition of the work material, requirements to N q/ r5 g6 i4 N8 @
the integrity of the machined surface, etc.
+ M* B2 j( u% sUnfortunately, while today's professionals, practitioners, and students are 0 A9 v& l6 ~8 r3 o M" d' f( V
interested in cutting tool geometry, they are doomed to struggle with the confusing
+ f: Q+ d4 n5 a1 k; h( O* |$ vterminology. When one does not know what the words (terms) mean, it is easy to
3 X" |3 N6 N' U% k/ @slip into thinking that the matter is difficult, when actually the ideas are simple, 6 u( o, Y9 y. ]# \8 Y
easy to grasp, and fun to consider. It is the terms that get in the way, that stand as a 2 z1 b$ X& l7 |0 l" n4 w
wall between many practitioners and science. This books attempts to turn those
: W' w |3 y2 X3 p5 O0 uwalls into windows, so that readers can peer in and join in the fun of proper tool
; ?0 a9 ]% }$ v5 ` H* Mdesign. % I, ^1 M: `5 g0 _" n1 v5 v0 E
So, why am I writing this book? There are a few reasons, but first and foremost,
6 L- g2 @. \& O% {: L% zbecause I am a true believer in what we call technical literacy. I believe that 3 M, l3 Y% o! W k
everyone involved in the metal cutting business should understand the essence and
; o) {0 A# ` G2 O* m1 M- i+ o7 Cimportance of cutting tool geometry. In my opinion, this understanding is key to ! [) B* }8 R' w
improving efficiency of practically all machining operations. For the first time, this % G+ I3 s7 {: K; ]& }# ?+ }+ ^
book presents and explains the direct correlations between tool geometry and tool
( J9 C$ s* @* n H& ?& mperformance. The second reason is that I felt that there is no comprehensive book
/ M) k! I$ O, E' Y: J+ N, I Gon the subject so professionals, practitioners, and students do not have a text from % r: Y" d0 @4 x3 C& ?% P
which to learn more on the subject and thus appreciate the real value of tool
/ F& F5 f9 H' I) Dgeometry. Finally, I wanted to share the key elements of tool geometry that I felt
. Q" F" i; Q- B3 N, D `- R6 N5 |, v! r' qwere not broadly understood and thus used in the tool design practice and in
/ z; O& D) O1 Z$ b7 E6 _optimization of machining operations in industry. Moreover, being directly
+ W0 B9 z8 l2 n+ Z- o# N$ r# vinvolved in the launch of many modern manufacturing facilities equipped with
1 K. z4 u7 Y! ]6 N: sstate-of-the-art high-precision machines, I found that the cutting tool industry is not 6 |/ C$ ], i$ T4 H
ready to meet the challenge of modern metal cutting applications. One of the key # h8 W$ ]6 _5 ?. ?& @ V( s1 W
issues is the definite lack of understanding of the basics of tool geometry of
+ x( ~9 B% X; {0 w6 {. Ustandard and application-specific tools. 0 Q5 g+ |! ]/ O" B- o
The lack of information on cutting tool geometry and its influence on the - f- z/ m' s3 q& N" @4 I) Y
outcome of machining operations can be explained as follows. Many great findings - T& X0 \- S& c8 `, x
on tool geometry were published a long time ago when neither CNC grinding
$ a, y; ], w8 s) @machines capable of reproducing any kind of tool geometry were available nor ' j1 h+ N6 _7 o) M, ~1 Y. d
were computers to calculate parameters of such geometry (using numerical
% ]6 a( c4 u r- p+ xmethods) common. Manual grinding using standard 2- and 3-axis simple grinding
2 D! [& z, c( _* sfeatures was common so the major requirement for tool geometry was the simpler C* l7 f- l7 }' h6 ~
the better. Moreover, old, insufficiently rigid machines, aged tool holders and part
. d$ n5 [* J5 `* ^" ]7 [4 j9 Hfixtures, and poor metal working fluid (MWF) selection and maintenance levered . x0 |' ~/ ~# ?) f
any advancement in tool geometry as its influence could not be distinguished under
/ J5 c2 K1 f. B1 t( k- othese conditions. Besides, a great scatter in the properties of tool materials in the
% A# Q+ h w$ spast did not allow distinguishing of the true influence of tool geometry. As a result,
. C/ {7 D6 G T* A" Fstudies on tool geometry were reduced to theoretical considerations of features of
/ T! F6 }: k4 w/ z( o) z% n; V+ w7 l% xtwist drills and some gear manufacturing tools such as hobs, shaving cutters,
4 O, d( n0 w9 {! F' ^3 S% Zshapers, etc.
, q4 y/ I1 Y- ^' a7 L+ NGradually, once mighty chapters on tool geometry in metal cutting and tool
, `4 W8 Q7 D* c, b! }2 [" N; Cdesign books were reduced to sections of few pages where no correlation between
* i7 t) [6 E" \; h. Ntool geometry and tool performance is normally considered. What is left is a : G) I& `% X, N' Q
general perception that the so-called “positive geometry” is somehow better than
. l% `! q& d5 y, B“negative geometry.” As such, there is no quantitative translation of the word
, m' t( b3 A1 v8 S1 {“better” into the language of technical data although a great number of articles - H# |- t V; x. J
written in many professional magazines discuss the qualitative advantages of $ S& H8 a8 n, I. r0 H1 R
“positive geometry.” For example, one popular manufacturing magazine article : `; W s* L7 H3 f
read “Negative rake tools have a much stronger leading edge and tend to push : \3 S# {+ C" `4 K& K
against the workpiece in the direction of the cutter feed. This geometry is less free ! q1 z+ l) _/ X7 l* _' r
cutting than positive rakes and so consumes more horsepower to cut.” Reading ( @4 x6 M6 Y" z- a ?8 X2 t" W
these articles one may wonder why cutting tool manufacturers did not switch their 3 K, U/ J) P3 t$ v" a) {1 K
tool designs completely to this mysterious “positive geometry” or why some of . `2 M- [! H# \8 s& S3 g3 @
them still investigate and promote negative geometry.
9 u) x' i# H/ lDuring recent decades, the metalworking industry underwent several important
- A1 o% y* \* B' c7 Z2 `changes that should bring cutting tool geometry into the forefront of tool design 8 ~3 j' H3 H/ K/ n4 ~& E
and implementation: |