Machining and Grinding Processes

Question 1

What is the difference between Machining and Grinding processes?

Answer 1

Machining: cutting a desired shape out of a billet
Grinding: using abbrasion to wear away the surface of a billet into a desired shape

Question 2

What are the three main types of machining processes

Answer 2

Single Point Cutting
Multiple point cutting
Abrasive cutting

Question 3

What is turning

Answer 3

the workpiece is rotated and a stationary cutting tool is put in contact with it to create rounded shapes.

Question 4

What are the 12 functions of a lathe?

Answer 4

Facing
straight turning
external grooving
drilling
boring and internal grooving
cutting(parting) off
taper turning
profiling
face grooving
tool forming
threading
kurling

Question 5

what requirement are needed for turned parts?

Answer 5

all internal corners need a radius >0.4mm
externa corners must be deburred and chamfered

Question 6

What is center drilling

Answer 6

drilling a hole that will act as a centre of rotation for following
drilling operation

Question 7

What is reaming?

Answer 7

A process of finishing holes or slightly removing material from the hole to align it with tolerances

Question 8

What is tapping?

Answer 8

a process used to crease small female threads

Question 9

What is Milling?

Answer 9

A rotating tool i used to cut away matterial from a billet at a set depth to create complex shapes

Question 10

What are the three types of vertical milling?

Answer 10

Face Milling
End Milling
T-slot milling

Question 11

What are the 5 types of horizontal milling?

Answer 11

Slab/ Peripheral milling
Slotting
Slitting
Form milling
straddle milling

Question 12

What are the requirements for end milling?

Answer 12

All internal corners have the radius of the end mill
all external edges must be deburred and chamfered

Question 13

Describe the structure of abrasive machining surfaces

Answer 13

A porous network of abrasive grits embedding into a tough matrix that holds them together

Question 14

What is Swarf?

Answer 14

waste chips of material cut away during machining

Question 15

What is the purpose of a chip breaker?

Answer 15

a tool which splits chip into smaller parts so they are not long enough to be dangerous or damage equitment

Question 16

What is machineability?

Answer 16

a materials ability to fracture under a small amount of strain as well as lower shear strength

Question 17

what rake angle should be used for soft materials?

Answer 17

large rake angles as they increase the length of the shear zone

Question 17

What is rake angle?

Answer 17

the angle of the cutting tools face normal to the surface of the material

Question 18

What rake angle should be used for brittle materials?

Answer 18

small if not zero angle as this improves the surface finish on a material prone to splintering

Question 19

how is the power needed for a cutting process determined?

Answer 19

P = (Specific energy x material removal rate)/ drive efficiency

Question 20

what causes a tool to fracture or chip?

Answer 20

Excessive stresses from high cutting forces often due to too deep cuts or too fast feed rates

Question 21

What causes tools to blunt or deform premeturely

Answer 21

Hard workpiece material causing high
cutting forces to be generated. Softening of tool due to lack of cooling

Question 22

What causes gradual wear and erosion in tools

Answer 22

Friction on flank causing gradual abrasive wear. Crater
wear on tool rake face due to abrasive wear from chip.

Question 23

Where is the highest temperature on the tool?

Answer 23

at the point of maxium friction and wear

Question 24

How is tool life determined ?

Answer 24

VT^n = C
T -> tool life
V -> cutting speed
n,C are constants from the specific cutting conditions

Question 25

What order should turning processes follow?

Answer 25

Facing -> turining -> Chamfering -> parting off

Question 26

What is a handling cost?

Answer 26

the cost of time loading and unloading machines

Question 27

What is machining costs

Answer 27

the cost associated wth the time taken to machine each part

Question 28

What is tooling cost?

Answer 28

the cost of all the components of the machinery and tools as well as their replacements