final manufacturing sem ii 20102011 & skema jawapan

7/26/2019 Final Manufacturing Sem II 20102011 & Skema Jawapan

1/16

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TEKNOLOGI

PEMBUATAN

BDA

3052

3

BDD

APRIL/MEI

2011

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SULIT


2/16

BDA

3052

,

PART A

(80

MARKS):

This

section

contains

FI\IE

(5) questions. Choose and

answer

any

FOIIR

(4)

questions

ONLY.

(a)

1

(b)

(d)

What

is a

casting

casting

procsss.

process?

State

three

(3)

capabiiities

and

advantages of

(4

marks)

(c)

Q2

(a)

(c)

(d)

(b)

Briefly

explain,

what is the

function

of

flask, riser,

core and

pattern

in

the

sand

casting

molds?

(4

marks)

With

the aid

of

a

sketch

state

the

investuient

casting process.

(7

marks)

A

mechanical

part

with the

tolerance

of *0.075 mm

with

small

thickness will be

produced using

a

casting

process.

The

product

needs

to

be

produced

in

a

high

quantity

and

good

quality

of

surface

finish and dimensional

accuracy with less

finishing

process.

In

order

to

produce this

part,

select

the best casting

process

and

discuss

why

it

is

selected.

(5

rnarks)

Draw

areatfigure

of a

force

diagam

shcwing

the

geometiic

relationship

between

all

the forces

acting

on

the chips

in

orthogonal

cutting.

(7

marks)

By

using

illushations,

distinguish

and

explain

two

forms of

milling

in

the

peripheral

milling.

Describe the

geometry

of

the

chip formed

by

this

process.

(6

marks)

List

down

three

(3)

processes

ttrat

can

be done

by

the

drill

machine other

than

making

ahole'

(3

marks)

Explain

the

important

steps

implemented

in

the

chemical machining.

(4

marks)


3/16

Q4

(c)

(d)

(e)

(a)

(b)

(c)

BDA

3052 .

List

all

the various

rolling

process

available?

(3

rnarks)

Briefly

explain

open

die

forging, impression

die

forging

and

flashless

forging.

(4

marks)

Explain

forward

and

backward

extrusion

assisted

with

figures.

(5

marks)

what

are

blanking,

piercing

/

punching,

bending

and

forming processes.

Give

example

for

each

one ofthe

procssses.

(4

marks)

In

general,

what

are

all

advantages

and disadvantages

of

hot

working

and

cold

working

processes?

(4

marks)

Explain

die

swell

in

plastic

processing.

(3

marks)

Explain

angle

of repose

in

plastics

(3

marks)

wha.lr

are

the

difFerences

betvr.een

thermoprastics

and

thermosets

plastics?

Give

examples

for each

one

of

them.

State

about

the

viscoelasticity,

viscosity,

calendaring

in

plastics

rr""::;;-'

(e)

Explain

wiflr figure

the

vacuum

thermoforming

process.

(5

marks)

(5

marks)

(d)

(a)

S

(b)

In powder

metallurgy

process,

packing

factor

is

a very

important

charactedstic

to

be

known.

Identifu

the

relationship

between packing

factor

and porosity

of

compacted

parts.

(3

marks)

welding

process

can

be

divided

into

two

major

categories.

what

are

the

two

major

categories

and

explain

their

differences

from

the

point

of

processing

fundamental.

Give

two

examples

for

each

category.

(8

marks)


4/16

(c)

BDA

3052

Welding

operator

found

out that

tfr.

:oirrt

result of

metal

inert

gas

CMIG)

welded

products

are

not

constant.

Some

of the

parts

were

seriously

bumt and

full

of

porosity.

There

were

welded

with

inconsistent

penetration

depth. List

out

thiee

(3)

possible

reasoils

and explain

the countermeasures

that

can be

taken.

(9

marks)

4


5/16

-

Q6

BDA

3052

PART

B

(20

MARI(S):

This

section

contains

THREE

(3) questions.

Choose

and answer

any TWO

(2) questions

ONLY.

ln an

orthogonal

cutting operation,

the cutting tool has a

rake

angle

of

5o. The

lathe is

set so

the chip

thickness befcre

the cut

is

0.25

nam.

After the cut, the deformed

chip

thickness

is

measured to be 0.7

mm.

Calculate:

(a)

the

chip thickness

ratio

(b)

the

angle

of

the shear

plane

(c)

the length

of the shear

plane

If a

cutting

tool

with a rake angle of

1

o

is used

in

this

cutting

process,

determine:

(d)

the

new length

of the

shear

plane

1

-----r

(e)

the

new angle ofthe shear

plane

By refening

to ail of

the results,

explain

the

reiation of

rake

angle

with

the length

and

angle of the shear

plane

in the orthogonal

cutting

operation.

Q7

(a)

(i0

marks)

A

work

piece

having

75 mrn

diameter

and length 300 mm is to

be

reduced

to diameter

of

69 mm as

final

size.

The

depth

of cut is

1 mm- The

work

piece

is

rotating at

900

RPM.

A carbide

tool of

8 degree rake angle

is

used.

The chip

thickness

is

1.3 mm.

The feed rate is 0.25 mm /rev.

d

=1f^^

"

-li-:--+

rJ

s

212,091'f

**/qr.

Calculate:

o{

.g"

N+-

,[s\-^,,

N

s

91m

t\

l'o

(i)

cutting

,,"l$ity,

lorr6tu'$=7. u

f . S-

(

o

-td

r'^-"

(ii)

The time taken to machine

up

to 69

mm diameter

to

a

lengfh

of 200 mm.

(iii)

Total

Material

Removal

Rate

(MRR)

hnr+s

w{,=

v{;"1

x(10y1

.f

(

n^)

$^

"+

s

lor:(o:ra")

(

.tr,r

(5

marks)

(b)

A slab

rnilling operation

iJperformed to

finish

tlie

top

surface of a

steel

work

piece

rectangular

in

section.

The size of

the

work material is

350

mm iength

and 7$ mm wide. A

helical

milling

cutter

,'which

has a

75

mm

diameter and

ten

teeth,

is

set up to machine. The cutting speed

is 130

m/min,

the

chip

load

is 0.15 mm/tooth

and depth

of

cut is

3 mm.

Calculate

the

following:

(i)

Time taken to make one

pass

across the

surface

and


6/16

Q8

BDA

3052

(ii)

Material

Removal

Rate

(MRR).

Tool life

tests

in turning yield

the

following

data:

r

when

cutting

speed

is

100

m/min,

tool

life

is

10

min:

:

when

cutting

speed

is

75

m/min,

tool

tife

is

30

min.

(a)

(b)

Detemrine

the

n and

C values

in

the

Taylor

tool

rife

equation.

Based

on

your

equation,

compute,

i)

the

tool

tife

for

a

speed

of

110

m/min,

and

ii)

the

speed

corresponding

to

atool

life

of

1j

min.

(5

marks)

(10

marla)


7/16

3052

Manu

nal

Exam

Se

51 (a)

(c)

(b)

Process

in

which

molten

metal

flows

by gravit-v

or

other

force

into

a

inoici

where

it

solidifies

in

the

shape

of

the

mold

cavity.

_

I

Advantages

of

casting:

Can

create

complex

paft

geometries

Can

create

both

external

and

internal

shapes

Some

casting

processes

arc

net

shope;

others

t*e

near

net

shape

Can

produce

ve{y

large

parts

Some

casting

methods

are

suited

to

mass

production

(1

mark

each,

max.

3

marks)

Flask

-

a

box

containing

two

parts

mold,

cope

and

drag

*

I

mark

Riser

-

is

a

reservoir

in

the

mold

that

serves

as

a

source

of

liquid

metar

for

flre

asting

to

compensate

for

stirintage

J**

solidification.

-

I

mark

r?:h:-irm

Placed

ir''side

the

mold

cavitv

to

defiae

the

interior

geomerry

of

Pattern

-

is

used

to

_forrn

the

mold

cavity,

made

of

wood,

metal, plastic

or

ther

material

which

has

the

rrrup.

"r*r"

part

to

be

cast

- r

mark

(4

marks)

wax

ffiH

patternffi

\wry

(r)

ffiffii

2)

(3)

(4)

#

W

6)

(1)

wax

pattems

are

produc

ed,

Q)several

patterns

are

attached

to

a

sprue

to

form

a

attern

tree (3)

trre

pattem

hee

is-coat"a

*itr,

"

ini*

r"r.r-"r*fractory

materiar,

(4)

he

full

mord is

formed

uv

.or..i"g"tjrJ

coated

t

".

*itl

,rrmcient

refractory

materiar


8/16

BDA

3052

to

make

it

rigid

(5)

the

mold

is

held

in

an

inverted

position

and

heated

to

melt

the

wax

and

permit

it

to drip

out

of

the

cavity,

(6)

the

mold is

preheated

to

a

high

temperature,

t]re

molten

metal

is

poured,

and

it

solidifies (7)

the rnotA

is broken

awJy

from

the

finished

casting

and

the

parts

are

separated

from

the

sprue

(1

mark

for

each

figure

and

explanation)

(d)

Die casting.

-

1

mark

(l)

highproductionrate

A)

hrge

production

quatities

(3)

closetolerance

possiblo

+0.026

for

small

part

(4)

good

surface

finish

(5)

thinsectionpossible

(6)

small

grain

size

and

and

good

strength

due

to

rapid

(1

mark

for

each

erl$wsr,

max

4

answers)

(a)

F:

friction

force,

N:

nonnal

force

to

&iction,

F.

:

shear

force,

Fn

=

normal

force

to

r\"*

force,

Fo:

cutting

force,

Ft:

thrust force,

R:

the resultant force

(

1

mark

for

each

answer)


9/16

BDA

3052

(c)

(d)

up

milling

(

l

mark)

down

rnilling

(1

mark)

up

Milling

or

conventional

miiling

-

the

direction

of

motion

of

the

cutter

cutter

teeth

is

opposite

the

feed

direction

when

the

teeth

cut

into

the

work.

(1

mark)

?oIn

Milling

or

climb

milling

-

the

direction

of

cutter

motion

is

the

sarne

as

the

feed

direction

when

the

teettr

cut

into

the

work.

(1

mark)

In

up

milling

the

chip

formed

by

each

cutting

tooth

starts

out

very

thin

and

increases

the

thickness

during

tlr"

,,r."p

of the

cutter.

(t

mark)

In

down

milring

the

chip

formed.

by

each

cutting

tooth

starts

out

very

thick

and

reduces

the

thickness

tlrroughout

the

cut.

(1

mark)

1.

Reaming

2.

Tapping

3.

Counterboring

4.

Countersinking

5.

Centering

6.

Spot

(1 mark

each

for

each

answer,

maximum

3

answers)

Cleaning

-

cleaning

operatioti

to

ensure

rnaterial

will

be

removed

uniformly

from

the

surfaces

etched.

Masking

-

a

protective.coating

called

laskanl

is

appiied

to

certain

portions

of

the

part

surface'

It

appiied

to

those

portions

of

the

#".t

,*a"e

that

are

not

to

be

etched.

Etching

-

the

part

is

immersed

in

an

etchant

that

chemically

attacks

those

portions

of

the

surface

that

are

not

masked

Demasftipg

-

The

maskant

is

removed

from

the

part.

(1

mark for

each answers)

*---__Trhla


10/16

S3

BDA

3052

(a)

Various

rolling

process

are:

i.

Two-High

Rolling

Mill

ii.

Three-High

Roliing

Mill

iii. Four-High

Rolling

Mill

iv.

Cluster

Mill

v.

Tandem

Rolling

Mill

iv.

Thread

Rolling

(3

marks)

(b)

Open-die

forging

-

work

is

compressed

between

two

flat

dies,

allowing

metal

to

flow laterally

with minimum

constraint

q, 6d.

lYq6.a

tw&(ddq0}l

lmpression-die

forging

-

die

coutains

cavity

or

impression

that is

imparted

to

workpart

Metal flow

is constained

so

that

flash is

created.

Flashless

forgrng

-

workpart

is

completely

constrained

in

die

No

excess

flash

is

created.

(4

marks)

(c)

As rarn

approaches

die opening,

a

small

portion

of

billet

remains

that

cannot

be

forced

through

die

opening.

This

extoa

portion,

called

the

butt,

must

be

separated

from

extrudate

by cutting

it

just

beyond

the

die exit

Starting

billet

cross

section

usually

round.

Final

shape

of

extrudate

is

determined

by die

opening.

4


11/16

Also

called

baclcward

extrusion

and

reverse

extrusion

Limitations

of

indirect

extrusion

are imposed

by

a

Lower

rigidify

of

hollow

ram

G

Difficulty

in

supporting

extruded

product

as

it

exits

die.

(e)

'The

punched

out part

from

the

strip

is

taken

for

subsequent

operation,

it is

called

blanking.

The punched

out part

from

strip

is

sluj

i**t"1ir

rcrap.

It

is

called punching

/piercing.

(e)

Advantages:

Hotworking

In

hot

working

process,

more

deformation

is possible.

Ductility

of the

material

is

good'

Final

product

shape

is

good.

Lower

forles

and power

trran

in

cold

working

More

intricate

work geometries

possible,

need

for

annealing

may

be

reduced

or

eliminated

Disadvantages

-Reduce

in

strength,

Scale

fonnation,

no

dimensional

control,

no

good

surface

finish.

CoId

Working:

Advantage:

increased

strength

that

results

from

strain

hardening.

Surface

finish

is

good.

Grain

flow

during

J."formation

can

cause

desirable

directional

properties

in

product.

No

heatLg

of

work

required.

Disadvantages-

Higher

forces

and. power

requirea

in

th;

deformation

operation,

Su.faces

of

starting

work

piece

muit

be

free

of

scaie and

dirt.

Q4

(a)

Flow

of

polymcr

___t'*

ffi--r

$Pi

Ia)

Extruded

polymer

"remembers"

its

previous

shape

when

in

the

rargersectian

of

the

extruder,

tries

to

return

ta it

after

leaving

the

die

orifice


12/16

(b)

RDA

3052

,

A

common

test

of

interparticle

friction

is

the

angle

of

repose,

which is the

angle

formed

by

a

pile

of

powders as they

are

poured

from

a nalrow

funnel.

\----_---Z

-/

\,/

\ ///,v

_

Funnet

tr

tt

L-l

Pile

of

powders

4

enste

of

repose

What

are the

differences between

thermoplastics

and

thermosets

plastics?

Give

examples

for each one

of them.

(4

marks)

Thermoplestics

Chemical

structure

remains unchanged

during

heating

and

shaping

More

important

commercially,

comprising

more

than

7O9lr of

total

plastics

tonnage

Can

be reused

after re-melting

Thermosets

Undergo

a curing

process

during

heating

and shaping,

causing

apermanent

change

(cr

o s s

-linking) in

molecular

structure

Once

cured,

they

carnot be

remelted.

Yiscosity

of

a

polymer

melt

decreases

with shear

rate,

thus

the

fluid

becornes

thinna

at higher

shear

rates.

Viscosity

decreases

with

temperatuxe,

t}us the

fluid

becomes

thinner

at

highet

ternperatures.

Yiscoelasticity

It

is

the

properfy

of

a

material that

determines

the

strain

it

experiences when

subjected

to

combination

of

siless

and

stain

Possessed

by

both

polymer

solids and

polymer

melts

Example:

die

swell

in

exkusion,

in

whichthe

hotplastic

expands

when

exiting

the die

opening.

Feedstock

is

passed through a series

of rolls

to

reduce thiclcress

to

desired

gage

Expensive

equipment,

high

production

rates. Process is noted

for

good

surface

finish

and

high

gage

accuracy.Typical

materials: rubber

or rubbery

thermoplastics

such

as

plasticized

PVC

(c)

(d)

Die

swell

I r"ra*o*

@

k

6


13/16

BDA

3052

il:iffi"lrl?;ry;X:,8:-,

shower

currains,

vinyl

rable

ctoths,

poot

riners,

/._kEk

re-eB{.*

w

fl)

(a)

(2t

(b)

(c)

l

mark

2

marks

Oxy-fuel

gas

welding.

I

mark

Total

Marks:

g

marks

ffiE{t_

L_lMl*

*--NN**

-N>XNN

(d)

S5

(a)

porosity

+

packing

factor:

1.

packing

factor

bulk

density

divided

by

true

density.

One

of

the

above

relation

)

2

marks.

Furtherexplaination

+

tmart


14/16

BDA

3052

(c)

-Torch

movement

speed.

-Need

constant

and

comect

speed.

-Current

and

voltage

setting

-Constant

and

correct

current

setting

-Shield

gas

flow

rate.

-Constant

and

enough

gas

to

shield

the

welding

area

until &e

melted

area

re-

solidified.

-Shield

gas

q4pe.

-Some

materials

are

reactive

against

certain

shield

gas

(titanium

and

nitrogen)

2

marks

(for

each

examFle

of

countermeasure).

I

mark (for

each

correct

explaination).

Total

marks:

9

marks


15/16

BDA

3052

s6

PART

B

(20

MARKS):

(a)

(b)

(c)

(d)

(e)

r

:

Ato:

0.2510.7

:0.357

_

2

marks

tan

.0 :

0.357(cos5)lt-(0.357

sin

5|

A366

:20.1o

_

2

marks

to:

ls

sin

0

.'.

ls

:0.2510.343

:0.72g

mm

_

1.5

mark

tan

$

:

0.357(cos1)

/t-(0.357

sin

l)

:

0.359

:

19o

_

2

marks

to=

ls sin

$

...

is

=

0.2510.325

:

0.769

mm

-

1.5

mark

(10

marks)

s7

(a)

1'

Cutting

velocity:

rc

x

d

x

N /

1000

=

3.142x

75

x

g00

/1000

:272mlmin.

2'

Time

taken: .lgm

of

turning

i feed

rate

x

RpM:200

/

a,5X

g00

:0.99

mins.

T_

=

L

Turning

to

be

done

by

ttu'ee

tir*J;im"ken

:

0.88

x3

:2.64minutes.

z.

i.)

MRR

for

75

mm

diameter:

v

x

d

x

feed

rate:

2r2

x1

x

0.25

ii)

MRR

for73mmdiamet.,

Iti;?of

iloi:rH#"boo

iii)

MRR

for

71

mm

diameter

:

2A0x

1

x

0.25

:

SO,tiOO

iv)

MRR

for

69

mm

diameter:

195

x

I

0.25

: qg,:lSO

Totai

IyIRR

=

53000

+

5i5000

+

50000

+

4g750:

cubic

mm

/min.

(5

marks)

(b)

cuttingverocity:zuxDxN/r000

=3.r4zx

75

xN:

130

N:

130

x

1000

/3.t4}x

75:551

R.PM

Feed

rate

:

N

x

number

of

teeth

x

chip

load:

551

x

10

x

0.25

:

826.5

Approach

length:75

mm.

i)

Time

taken

to

machine

:

(L

+

75)

/ feed

rate

ii)

Mry:.*

*

d

x

reed

,ut"

I

[t:

ii?r8;

];f;3iffiff:

rnm

/

mln^

Increasing

the

rake

angle,

will

increase

the

shear

angle

and

reduce

the

length

of

shear

lane.

-

1

mark

(5

marks)


16/16

(a)

BDA

3052

Yg-.^qy,ions:

(t)

100(10)"=

C

and

e)75(30).:

g.

100(10)'

:75(30)"

n

100

+

nla

l0

= Ia

75

+

n11139

4.61+2.3

n=

4.31+3.4

n

4.61"

- 4.31

=

(3.4

_2.3)

n

n=5.27

:= 100(10)0:7

=

r g(1.80

C=

186

Check

C:75(30)o'7

=

ZSt3Oo.27

= t{,.g

ll1

f27:

186.0

f'27

=

186.0/ll0=

1.69

T=

l.6gtn27

:1.693.7

=

6.97

min

u

(15)0'27:

186.0

v

= 186.0(15,)02?

=

186.0/2.07

=g9,g6

m/min

(b)

4

marks

3

marks

3

marks

(c)

":t'

E:

final manufacturing sem ii 20102011 & skema jawapan

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