Metal Cutting 2 Flashcards
What are the results of a Positive rake angle?
Sharper cutting edge (typically better finish) Reduce shear plane size Lower strain than negative rake Lower cutting force Lower power consumption
What are the results of a negative rake angle?
Stronger edge (longer tool life) Increase shear plane size Tool (or insert) can be turned over (more economical) Require higher cutting force Typically larger cutting depth
What is Orthographical cutting?
The cutting edge is straight and set at a position that us perpendicular to the direction of primary motion
What is Oblique cutting?
The cutting edge is set at an angle. Stress and strain conditions are three dimensional
What is single point cutting?
The cutting tool has only one main cutting edge: turning, shaping, boring
What is multi-point cutting?
The cutting tool has more than one major cutting edge: Drilling, milling, reaming
Continuous chip properties
Ductile, large positive rake angles, fine feeds and high speeds
Discontinuous chip properties
Brittle, negative rake angles. coarse feeds and low speeds.
Built up edge chips
Lower surface finish but life of tool is increased. good for rough cutting.
What are 2 types of chip breakers?
External and Integral
Name the favourable chip formations
Spiral chip segment and discontinuous chip
What is the hottest part of the tool?
Above the cutting point. Chip acts like heatsink taking temperature away from the tip.
What are the main reasons for chatter marks?
Part vibrates and tool bounces while cutting
Machine vibrates
Material inconsistency
Discontinuous cutting shapes
What are the solutions to reduce chatter marks?
More stable machines - tuned damper Rigid support for workpiece Minimising tool overhang Modify cutting geometry Change cutting parameter, e.g. speed, depth, feed, fluids
