12-09-2012, 04:33 PM
Mechanics of Machining (Metal Cutting)
Instructional objectives
At the end of this lesson, the student should be able to :
(a) conceive rake angle and clearance angle of cutting tools
(b) classify systems of description of tool geometry
© demonstrate tool geometry and define tool angles in :
• Machine Reference System
• Orthogonal Rake System and
• Normal Rake System
(d) designate cutting tool geometry in ASA, ORS and NRS
Geometry of single point turning tools
Both material and geometry of the cutting tools play very important roles on their performances in achieving effectiveness, efficiency and overall economy of machining.
Cutting tools may be classified according to the number of major cutting edges (points) involved as follows:
• Single point: e.g., turning tools, shaping, planning and slotting tools and boring tools
• Double (two) point: e.g., drills
• Multipoint (more than two): e.g., milling cutters, broaching tools, hobs, gear shaping cutters etc.
(i) Concept of rake and clearance angles of cutting tools.
The word tool geometry is basically referred to some specific angles or slope of the salient faces and edges of the tools at their cutting point. Rake angle and clearance angle are the most significant for all the cutting tools.
The concept of rake angle and clearance angle will be clear from some simple operations shown in Fig. 3.1