Chapter 17 Flashcards Preview

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Flashcards in Chapter 17 Deck (28):
1

What are the 3 modes of failure in tools

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

2

Where does gradual wear occur in single point cutters
(2)

crater wear: top rake face

flank wear: on flank (side of tool)

3

Describe 3 sections of tool wear vs time

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

4

Taylor tool life equation

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

5

two highest hot hardness materials

high speed steel or plain carbon steel

cemented carbides and ceramics.

high speed steel

6

Diff b/w high speed steel alloys

Tungsten

good hardness
wear resistance

7

Diff b/w high speed steel alloys

Chromium
Vanadium

corrosion since working fluids will corrode steel

Creep resistance

8

Diff b/w high speed steel alloys

Carbon

want carbide for strength

9

Diff b/w high speed steel alloys

Cobalt

binder
increases toughness

10

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

18 W, 4 Cr, 1 V, 0.9 C

11

Name two cemented carbides. What do they cut.

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

12

prop of cemented carbides 7

high compressive strength
low tensile

high hardness
high hot hardness

good wear resistance

high thermal conductivity

high elastic modulus

13

name cermets. used for on what

TiC, TiN, TCN
high speed finishing of steels, stainless steels, and cast irons

14

why coated carbides. used for on what.

cemented carbide inserts with TiC, TiN, alumina

for cast irons and steels in turning and milling

15

Name ceramic used in cutting. for what. downside

fine grained alumina.
cast iron and steel
low toughness

16

what is a synthetic diamond made of and what used for

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

17

cubic boron nitride. what for and what material

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

18

3 diff single point tool

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

19

Name layers in inserts

TiN coating
alumina
TiC
Carbide substrate

reason. can't get all prop on one layer

20

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

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

Sharper angles are more versatile and accessible

21

benefit of chip breaker

no long chip
control chip flow
reduce vibration and heat generated

22

twist drill material
problem

hss

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

23

3 milling cutters

plain : 18 tooth cutter

face: 4 tooth

end: like drill bit but does many things.

24

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

well speed big.
feed moderate
depth of cut small

25

what do cutting fluid do. (5)
benefits of filtration (5)

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

26

two cutting fluid
3 prop.

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

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

27

Machinability factors (4)
criteria in producation (4)

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.

28

important cutting conditions 6

machine tool
cutting tool
depth of cut
feed
speed
cutting fluid