Grinding, Abrasive Machining And Finishing Operation

Question 1

Define/describe Grinding

Answer 1

Chip removal process that uses individual abrasive grain as cutting tool.

Grains are irregular shaped, randomly spaced along peripheral of wheel

Negative grain angle. Lead to high plastic deformation

Spd are very high

For producing high dimensional accuracy and fine surface finish

Question 2

Abrasive material of Grinding

Answer 2

Types - conventional/superabrasive
Held together by bonding material

Question 3

Type of grinding wheel

Answer 3

Straight
Cylinder
Straight cup
Flaring cup
Depressed center
Mounted

Question 4

What is Bonding material and types

Answer 4

• supporting post or braces between grains
• types:
  Vitrified- glass bond (brittle)
  Resinous- thermosetting resins (resistant to high temp)
  Reinforced wheel - prevent breakage
  Rubber -flexible inexpensive
  metal - most inexpensive

Question 5

Chip dimension formula

Answer 5

Chip length, l = √(Dd), d depth, D diameter

Chip thicc, t = √(4v/VCr) √(d/D)

Question 6

Grain force formula

Answer 6

(v/V) (√(d/D) )

Question 7

Energy required during grinding are cuz by

Answer 7

Plastic deformation in chip formation
Plowing, ridges formed
Friction

Energy are high cuz of negative rake

Question 8

Temperature dependence

Answer 8

Temperature rise in grinding causes expansion and contraction = residential stress.

Temp rise = D^1/4 d^3/4 (V/v)^1/2

D-wheel diameter
d-depth cut (biggest factor)
V- wheel speed
v- workpiece speed

Question 9

What happens when temperatures rises in grinding

Answer 9

W/piece soften
Ground surface burn
Surface crack
Sparks from oxygen+chips

Solution: coolant, reducing V, increasing v

Question 10

Problem of grinding

Answer 10

Wear flat (parts of grain become flat) - cause friction

Sparks - hot chips

Tempering - w/piece soften from heat

Burning - burn ground surface

Heat checking - cracks

Question 11

Grinding wheel dressing

Answer 11

Returns grinding wheel to its original sharpness by removing old grain

Question 12

Common grinding machine/operation

Answer 12

Surface grinding (flat surface grinding)
Cylindrical grinding ( wp axial and grinding wheel free to move around)(good for complex shapes)

Question 13

Grinding operations

Answer 13

Centerless grinding
Internal grinding
Creep fed grinding

Question 14

Type of internal grinding

Answer 14

Transverse grinding (parallel)
Plunge grinding (perpendicular)
Profile grinding

Question 15

Grinding fluid

Answer 15

Prevent temp rise
Improve sf and dimensional accuracy
Reduce wear, loading, power consumption

Question 16

Ultrasonic machining process

Answer 16

Abrasive slurry being “punch” by tool

Question 17

List of finishing operations

Answer 17

Coated abrasives
Belt grinding
Wire brushing
Honing
Super finishing (rolling wp against stone)
Lapping (polishing? To wear down ridges)
Chemical mechanical polishing
Electroplating (remove metal from surface)

Question 18

Deburring operation

Answer 18

Wire brushing
Vibratory and varrel finishing (pellets tumbled/vibrate)
Abrasive flow machine (abrasive putty forced thru pipe)
Thermal energy deburring ( ignite burr with o2 and gas)
Robotic deburring (force feedback program)