Over all for midterm

Question 1

machining

Answer 1

process of removing material from a workpiece and forming chips

Question 2

7 basic chip formation processes

Answer 2

turning, drilling, milling, grinding, sawing, shaping and planing, broaching

Question 3

cutting speed

Answer 3

V
linear velocity that the tool passes through the workpiece or vice versa

Question 4

cutting speed depend on

Answer 4

material of tool and whats being worked on

Question 5

feed

Answer 5

amount od material removed per rotation or pass

Question 6

machine feedlinear

Answer 6

linear velocity of the tool or workpiece

Question 7

cutting time

Answer 7

time it takes to cut and made up of length of what is being cut and the allowance

Question 8

details about orthogonal machining

Answer 8

rake angle is the angle between the vertical and the tool

clearance angle is the tool makes with the workpiece

chip thickness ratio (rc)= t/tc
where t is the uncut chip thickness/depth of cut = AB sin p

and tc us the sheared chip thickness = AB cos(p-a)

typically tc is thicker than t due to material compression

Question 9

free vibration

Answer 9

system oscilate independently after distrbd frm eqlbrm postn and then released without any xtrnl forces on it. motion remains until energy dissipates

Question 10

forced vibration

Answer 10

oscillatory motion of a system subject to external forces snd rewuire continuous or periodic input of energy

Question 11

self excited vibratiin

Answer 11

sstm generates its own oscillation from its own dynamics and can sustain w/out anu external intrfrnce

Question 12

chatter

in what direction respect to blade ?

Answer 12

an undersirable phenomnn where machnng tools make irregular vibrations while cutting and can happen from any of the 3 types of vibration but usually self excited

same direction as blade edge usually

Question 13

chattter can be seen as … in machining focus

Answer 13

noise
tool wear
poor surface finish
when machining

Question 14

how can chatter issue be resolved

Answer 14

increase cutting force

Question 15

feed marks

Answer 15

parallel lines that occur because of irregular feed rate while cutting

Question 16

for corner making

Answer 16

tool radius should be smaller than intended radius of making to not get chatter

Question 17

name 6 Cutting tool materials

Answer 17

• High carbon steels
• Low/medium alloy steels
• High-speed steels (HSS)
• Cast cobalt alloys
• Cemented/cast/coated carbides
• Coated high speed steels
• Ceramics
• Sintered polycrystalline cubic boron nitride (CBN)
• Sintered polycrystalline diamond
• Single-crystal natural diamond

Question 18

what are the requirements of cutting tools

Answer 18

*High hardness
*High hot hardness
*Consistent tool life
*Good thermal properties
*High toughness
*High elastic modulus (stiffness)
*Resistance to abrasion, wear, chipping
*Strength to resist bulk deformation
*Chemical stability with temperature
*Correct geometry and surface finish

Question 19

tool steels (both Carbon steels and low/medium alloy steels)

Answer 19

If cutting temp goes above 400°F, they lose their hardness and cutting edges dull quickly.

Low temp associated with low cutting speed (V)

Sometimes referred to as silver steel or drill rod

Question 20

hss

Answer 20

Temperature up to 1100°F, better than Tool Steel

High Alloy Steel – Contains tungsten, molybdenum, cobalt, vanadium and chromium as alloying
elements.

*Great toughness
*Easily fabricated (grinding)
*Great for complex geometries

Question 21

Cast Cobalt Alloys

Answer 21

Cobalt rich alloy

Similar to HSS

Better heat hardness than HSS (so higher cutting speeds)

Question 22

why are cast cobalt alloys being phased out

Answer 22

being phased out due to cost of production, and
reduction in $ of better alternatives!

Question 23

what are the 2 primary grades of carbides

Answer 23

1. Straight tungsten grades (C2)
2. Grades containing major amounts of titanium, tantalum and or columbium. (C6

Question 24

Carbides and thw types of tools they come as

Answer 24

➢Solid Carbide (usually end mills or drill bits (some taps)

➢Brazed insert tooling (good if custom profiles need to be ground, most similar to HSS usage)

➢Insert tooling – Replaceable, easy to service, multiple cutting edges, maximum tool life and
productivity.

insert is usually better than brazed insert

Question 25

ceramics

Answer 25

Biggest limitation is
machine and tool holder
rigidity due to the high
hardness and therefore
high brittleness.

Question 26

Diamonds, PCD and PCDN

Answer 26

put dimnd on sintered crbide substrate
laser dice
braze into standard carbide sa tungsten insert

Question 27

common tool coatings

Answer 27

2 most common tool coatings
* Titanium Nitride
* Titanium Carbide

Question 28

tool coatings Applied via

Answer 28

Applied via Chemical or physical vapour deposition. (CVD and PVD)

Question 29

Why coat the tools???

Answer 29

• Resist wear, reduce friction, increase surface hardness., high hardness means higher cutting speed!

Question 30

PVD

Answer 30

All HSS, Solid carbide and carbide tipped
Virtually all tooling materials

Question 31

Cutting Fluids

Answer 31

Primary function = Coolant
Secondary Function – Lubricant
Tertiary Function - Chip evacuation, prevents chips from damaging the cutting
edges.

Question 32

Cutting Fluids Types

Answer 32

Types:
1. Flood
2. MQL
3. Through tool can be used with lathe
4. Air blast, similar to flood but no liquid.
Modern use is MQL = Minimum quantity lubrication system

Question 33

Broaching

Answer 33

*Broaching is where a tool, with successively
increasing tooth size, is moved through the
workpeice, creating the desired shape with a single
pass.

*Broaching requires multiple passes

Question 34

Fundamentals of Broaching

Answer 34

In broaching, the tool (or work) is translated past the work (or tool) with a single stroke of
velocity V.

The feed is provided by a gradual increase in height of successive teeth.

Question 35

what is RPT

what does it depend on

Answer 35

vertical distance difference between the two teeth that dont have the same size
not that teeth rise only for a specific section then it stops.
The rise per tooth varies depending on whether the tooth is for roughing (tr), semifinishing (ts),
or final sizing or finishing (tf).

Question 36

Advantges of broaching

Answer 36

Advantages and Disadvantages
*Broaching is a rapid method of producing a finished feature.
*Complex geometries are possible using broaching
*Standard keyways can used off the shelf tooling

Question 37

disAdvantges of broaching

Answer 37

*Custom tools must be produced for each feature at $15K to $30K per tool

*Broaching requires that the geometry be two
dimensional with a straight profile.

*Broaching requires that the tool be able to pass fully through the part.

*Broach designs require that the tool be stiff enough for the work required, small geometries are
a challenge.