chapter 13 def.

removal processes

machining, abrasive processes, nontraditional processes

cutting temperature

most of the energy goign into machining operation is generated by heat (98%)

cutting temperature importants

reduce tool life, produce hot chips that pose safety hazards to the machine operator, can cause inaccuracies in part dimensions due to thermal expansion of work material

material removal def.

removal of material from a starting workpart so the remaining part has the desired geometry

milling

rotating multiple cutting edge tool is moved across work to cut a plane or straight surface

rough vs finishing cuts

rough - removes large around of material from starting workpart finishing- completes part geometry

serrated chip

semicontinuous saw tooth appearance, cyclical chip form with alternating high shear strain then low shear strain. associtated with difficult - to machine metals at high cutting speeds

turning

single point cutting tool removes material from a roatting workpiece to form a cylindrical shape

cutting conditions

based off cutting speed, feed, depth of cut

discontinuous chip

brittle work materials, low cutting speeds, large feed and depth of cut, high tool-chip friction (irregular surface due to chip discontinuities)

4 types of chips

discontinuous chip, continuous chip, continuous chip with built - up edge, serrated chip

continuous with built up edge(BUE)

ductile materials, low to medium cutting speeds, tool chip friction causes portion of chip to adhere to rake face, BUE forms then breaks off cyclically

continuous chip

ductile work materials, high cutting speed, small feeds and depths, sharp cutting edge, low tool- chip friction (good finish typically)

machining operations

turning, drilling, milling

drilling

used to create a round hole, usually by means of a rotating tool with two cutting edges

why machining is important

variety of work materials can be machines, variety of part shapes and special geometric features, good dimensional accuracy and surface finish

disadvantages of machining

wasteful or material, time comsuing