Chapter 17

Question 1

What are the 3 modes of failure in tools

Answer 1

fracture failure: cutting force is excessive and leads to brittle failure

Temperature failure: cutting temp too high for tool

Gradual wear: gradual wearing of tool

Question 2

Where does gradual wear occur in single point cutters

2

Answer 2

crater wear: top rake face

flank wear: on flank (side of tool)

Question 3

Describe 3 sections of tool wear vs time

Answer 3

rapid initial wear
uniform wear (steady state)
accelerating wear rate (failure region)

Question 4

Taylor tool life equation

Answer 4

vT^n = C
cutting speed v
tool life T
n is slope of plot parameter
C intercept on speed axis at one minute

Question 5

two highest hot hardness materials

high speed steel or plain carbon steel

Answer 5

cemented carbides and ceramics.

high speed steel

Question 6

Diff b/w high speed steel alloys

Tungsten

Answer 6

good hardness

wear resistance

Question 7

Diff b/w high speed steel alloys

Chromium
Vanadium

Answer 7

corrosion since working fluids will corrode steel

Creep resistance

Question 8

Diff b/w high speed steel alloys

Carbon

Answer 8

want carbide for strength

Question 9

Diff b/w high speed steel alloys

Cobalt

Answer 9

binder

increases toughness

Question 10

Grade T1 HSS tools composition w, cr, v, c

Answer 10

18 W, 4 Cr, 1 V, 0.9 C

Question 11

Name two cemented carbides. What do they cut.

Answer 11

Non steel cutting grades WC-Co
cuts nonferr metals and gray cast iron

Steel cutting grades
TiC & TaC added to WC-Co
cuts low carbon, stainless

Question 12

prop of cemented carbides 7

Answer 12

high compressive strength
low tensile

high hardness
high hot hardness

good wear resistance

high thermal conductivity

high elastic modulus

Question 13

name cermets. used for on what

Answer 13

TiC, TiN, TCN

high speed finishing of steels, stainless steels, and cast irons

Question 14

why coated carbides. used for on what.

Answer 14

cemented carbide inserts with TiC, TiN, alumina

for cast irons and steels in turning and milling

Question 15

Name ceramic used in cutting. for what. downside

Answer 15

fine grained alumina.
cast iron and steel
low toughness

Question 16

what is a synthetic diamond made of and what used for

Answer 16

sintered polycrystalline diamond
coating for WC-Co
nonferr metals and abrasive nonmetals

Question 17

cubic boron nitride. what for and what material

Answer 17

hardest material known
coating for WC-Co insert
steel and nickel based alloys

Question 18

3 diff single point tool

Answer 18

solid shank HSS
brazed cemented carbide insert
mechanically clamped insert. used for very hard too materials.

Question 19

Name layers in inserts

Answer 19

TiN coating
alumina
TiC
Carbide substrate

reason. can’t get all prop on one layer

Question 20

Insert shape correlation to strength, power req, vibration tendency, versatility and accessibility

Answer 20

rounder has more strength, power req, and vibration tend.

Sharper angles are more versatile and accessible

Question 21

benefit of chip breaker

Answer 21

no long chip
control chip flow
reduce vibration and heat generated

Question 22

twist drill material

problem

Answer 22

hss

chip removal. friction buildup. no fluid at drill tip.

Question 23

3 milling cutters

Answer 23

plain : 18 tooth cutter

face: 4 tooth
end: like drill bit but does many things.

Question 24

correlation b/w speed, tool life, feed, and depth of cut

Answer 24

well speed big.
feed moderate
depth of cut small

Question 25

what do cutting fluid do. (5)

benefits of filtration (5)

Answer 25

reduce heat gen at shear and friction zones
friction at tool-chip and tool-work interface.
wash away chips
reduce temp of work
improve dimensional stability.

prolong fluid life.
reduce disposal cost
reduce healt hazard
low machine maint.
longer tool life

Question 26

two cutting fluid

3 prop.

Answer 26

coolants: Water based. High cutting speeds. For HSS susceptible to Temp failure

lubricants: Oil based.
low cutting speed.
reduces temp of operation

Question 27

Machinability factors (4)
criteria in producation (4)

Answer 27

work material
machining operation
tooling
cutting conditions

better machin. longer tool life
lower forces and power, better machin.
better finish better machin.
easier chip disposal, better machin.

Question 28

important cutting conditions 6

Answer 28

machine tool
cutting tool
depth of cut
feed
speed
cutting fluid