Machining Fundamentals

Question 1

is there wastage of material in machining

Answer 1

there is no wastage of material in rolling,forging,casting, but there is in machining

Question 2

whats the main diff. from rolling,forging extrusion and machining

Answer 2

deforming and removing material

Question 3

what is an abrasive process

Answer 3

material removal by hard, abrasive particles. i.e grinding

Question 4

what is non traditional processes

Answer 4

various energy forms other than sharp cutting tool to remove material. i.e lasers, edm)electric/mechanical power)

Question 5

material removal process

Answer 5

machining is important to remove stock material (steel bar, aluminim plate etc)

chips are the peices that fly away

Question 6

what does the cutting action of machining involve

Answer 6

shear deformation of work material to form chips

Answer 7

rake face difect the flow of material(the chip) out of the cut zone

flank: has a relief/clearnace angle to prevent the cutting tool from coming into contant to new surface

alpha-rake angle: can be either positive(clockwise) negatuve(anti)

Question 8

machining is important becuase…

Answer 8

-good surface finish
-good for prototypes and mold (dies for casting)
- variety in shape(screwes)
-good dimensional accuracy

Question 9

the greatest disadvantage is…

Answer 9

waste of material and time consuming since youre removing layer by layer

Question 10

types of machining operations

Answer 10

1. turning
   - workpeice is rotating
   speed: surface speed of work
   - increase diamater, spead increases

feed: tool is fed paralell to the work axis

depth of cut: Tool penetrated beneath original work surface (how much it goes beneath the surface)

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

2 forms: peripheral face and milling face

feed: work feeds in the direction perpendicular to the tool axis

depth of cut is tool penetrates beneath original surface
3. Drilling
speed is defines by drill bit diameter

it is fed parallel to the tool axis

depth is depth of hole
examples: sawing, shaping and planing, broaching, grinding

Answer 11

turning : workpiece is rotating
single point cutting operation

drilling/milling: cutting tool is roating
multipoint cutting operation

Question 12

what is the equation for material removal rate?

Answer 12

R_MR= vfd

v= cutting speed
f=feed
d=depth of cut

Answer 13

rough finishing: higher removal rate

final finish: lower removal rate

Question 14

rough cut + finish cut =

Answer 14

accurate size and good surface finish

Question 15

cutting fluid is…

Answer 15

applied to cool and lubricate the cutting tool (depends in work material and tooling)

Question 16

is the cutting tool harder or softer than the work peice material?

Answer 16

harder

Question 17

orthogonal cutting (2d cutting)

Answer 17

Tool Edge perpendicular to the movement of the tool
- chips slide over the tool
- uses wedge shapes tool-cutting edge perpendicular to the direction of cutting speed
- chip is formed by shear deformation along a plane called the shear plane

Question 18

describe the orthogonal cutting model

Answer 18

T_o= thickness of the chip prior to chip formation
T_c= thickness of chip after formation
L_s= length of shear plane

ratio : r=T_o/T_c «««< 1

Question 19

what is the significance of the shear angle

Answer 19

it affects force and power requirements, chip thickness, and temperature

Question 20

orthogonal cutting equations

Answer 20

T_o= L_ssin(phi)
T_c= L_scos(phi-alpha)

Question 21

Normal stress equation

Question 22

shear stress equation