1.1.2 Essential definitions for the working parts of cutting tools
1.1.2.1The basicelements for the
working part of cutting tool
(1) Rake surface(2) Flank(3) Cutting edge(4) Tool nose
Fig.1.3 components of typical turning tool
(1) Rake face Rake face Aris the surface on which the chip acts directly and which can tools the direction of the chip flowing out . The part
adjoining the major cutting edge is referred to as the major rake face; the part adjoining the minor cutting edge is referred to as the minor rake face.
（2）Flank There are a major flank and a minor flank. The major flank Aαis the surface which is opposite to the surface on the workpiece; the minor flank A’αis the surface which is opposite to the machined surface on the workpiece
（3）Cutting edge Cutting edges are the edges engaged in cutting on rake face. There
are major cutting edge and the minor cutting edge. The major cutting edge is an intersecting line between the rake face and major flank, it performs the principal work of metal removal. The minor cutting edge is an intersecting line between the rake face and the minor flank, it plays a subsidiary role in cutting.
（4）Tool nose The tool nose may be an intersecting point of major and minor cutting edges, or an intermediate straight line or a circular arc.
1.1.2.2Reference system for the marked angles of cutting tools
predetermined motion condition：first, predetermine the direction of main motion and the direction of feeding motion of the tool, then, assume that the feeding speed is very low so that the main motion vector vccan substitute for the combined speed vector veapproximately, then the reference system can be
composed of coordinate planes that are parallel or perpendicular to the direction of the main motion.
Predetermined condition for setup: assume the planes in reference system are parallel or perpendicular to the base plane of the tool which is easy for grinding and setup
The reference system consists of the following planes：
Tool reference plane Pris a plane which passes
through a designated point on the cutting edge and is perpendicular to the vector veof combined speed. Usually it is parallel or normal to the setup plane or axis of the tool arbor. For instance, in Fig.1.6, Pr is the reference plane for turning tool or planing tool,it is parallel
（1）Tool reference plane Pr
to the base plane of the cutting tool.
(2) Tool cutting edge plane Ps
Tool cutting edge plane Psis a plane which passes through a designated point on the cutting edge and is tangential to the cutting surface,namely, the plane formed by vector veof combined speed and the tangent line of a designated point on the cutting edge
Fig.1.6 the reference plane Prof an ordinary turning tool
（3）Main section P0and main section reference system
Main section Pois a plane which passes through a designated point on the cutting edge and is perpendicular to the tool reference plane Prand the tool cutting edge plane Ps
simultaneously. Fig.1.8 shows a main section reference system composed of Pr－Ps －P0
（4）Normal section Pn and normal section reference system
Normal section Pnis a plane which passes through a designated point on the cutting edge and is perpendicular to the cutting edge. The normal section reference system is composed of Pr—Ps—Pn,shown as Fig 1.8
Fig.1.8 main section and normal section reference system