tugas 02-1106068245

8/12/2019 Tugas 02-1106068245

1/12

8/12/2019 Tugas 02-1106068245

2/12

SATRIO WIBOWO (1106068245)

(6) Soft soldering ( C )

(7) Submerged arc welding ( A )

(8) Resistance spot welding ( B )

(9) TIG welding ( A )

(10) Ultrasonic welding ( B )

[Q3]

Welding process may be classified according to the type of energy source used directly for

welding. Choose the welding process from Group B that belong to the energy source in Group A,

and put the corresponding marks in the parentheses.

Jawab:

[Group A]

(1) Electric energy ( a, b, d, e, g, h, i )(2) Mechanical energy ( j )(3) Chemical energy ( c, i )(4) Light energy ( f )

[Group B]

(a)

Submerged arc welding (b)

Electro-slag welding(c) Explosion welding (d) Plasma arc welding(e) SMAW (Manual Metal Arc Welding) (f) Laser welding(g) MAG welding (h) Resistance welding(i) Oxy-flame (gas) welding (j) Friction welding[Q4]

Welding process may be classified according to the types of energy source utilized directly for

welding. Choose the energy source in [Word group] that is applied in each welding process, and

put its alphabet into each ( ).

Jawab:

(1) MAG welding ( a )

8/12/2019 Tugas 02-1106068245

3/12


(2) Aluminothermic welding ( c )(3) Electron beam welding ( a )(4) Oxy-fuel gas welding ( a )(5) Friction stir welding ( b )(6) Laser welding ( d )(7) Manual metal arc welding (SMAW) ( a )(8) Explosion welding ( c )(9) TIG welding (GTAW) ( a )(10) Electroslag welding ( a )

[Word group]

(a) Electric energy (c) Chemical energy(b) Mechanical energy (d) Light energy[Q5]

Regarding the future of the following welding and cutting processes, choose the relevant one

from among the words in the word group given below and enter its alphabetic symbol into each

parenthesis.

Jawab:(1) MAG welding ( a )(2) Laser welding and cutting ( d )(3) Submerged arc welding ( a )(4) Friction welding ( b )(5) Gas welding ( a )

[Word group]

(a) Electrical energy(b) Mechanical energy(c) Chemical energy(d) Light energy

8/12/2019 Tugas 02-1106068245

4/12


[Q6]

Regarding the classified of welding processes, choose five (5) gas-shielded arc welding

processes and encircle their alphabets.

Jawab:

(a) Stud welding (b) TIG welding (c) Laser welding(d) Submarged arc welding (e) Self-shielded arc welding (f) MAG welding(g) Shielded metal arc welding (h) Electro-slag welding (i) Brazing(j) Electro-gas arc welding (k) Resistance spot welding (l) MIG welding(m) Electron beam welding (n) Plasma arc welding[Q7]

In case of using 100% CO2 gas as shielding, dropletsizeisbecominglargerthanthatincase of using

CO2Argon gas mixture. Explainthereasons.

Jawab:

Setiap gas memiliki disosiasi yang berbeda-beda. Jika gas CO2 dibandingkan dengan gas Argon,

gas CO2 memiliki energi yang jauh lebih tinggi dan heat loss yang tinggi. Akibatnya menahan

molten metal dimana sebagian jatuh dan sebagian masuk ke sebagaian lasan. Selain itu apabila

>30% CO2 tidak ada mekanisme spray transfer.

[Q8]

The following sentences describe the metal transfer modes. Choose the relevant one and put its

alphabet into each parenthesis.

Jawab:

(1) The molten metal droplet, which is detached from the tip of the electrode by thearcforce,

transfers along the cavity wall in the flux covering around the electrode. This metal transfer

mode can be observed in submerged arc welding. (b)

(2) The molten metal drop let is punctured by rapid expansion of the internal gases generated in

thedroplet.This metal transfer mode can be observed in shielded metal arcwelding. (d)

(3) The molten metal drop let grows insize as large as the electrode diameter orlargerto transfer.

8/12/2019 Tugas 02-1106068245

5/12


This metal transfer mode can be observed in shielded metal arc welding with low-hydrogen type

electrode sand CO2-shielded arc welding with high currents. The both amount and size of the

spatter increases in general. (e)

(4) The molten metal drop let whose diameter is as small as the electrode diameter or small er

transfers in freeflight in thearccolumn. This metal transfer mode can be observedin MAG

welding with high current sand Ar-rich shielding gas (Ar: 80% orlarger) and MIG welding. In

general, spatter decreases, and the arc is likely to become stable. (a )

(5) The molten metal drop let, which is developed on the tip of the electrode, makes a contact to

the weld pool and is transferred with the aids of the electromagnetic pinching effect and the

surface tension of the drop let. This metal transfer mode can be observed in MIG and MAG

welding with low current, low arc voltage, and short arc length. This transfer mode issuitable for

sheet metal weldingandall-positionwelding. (c )

[Word group]

(a) spray transfer (b) flux-wall-guided transfer

(c) short-circuiting transfer (d) explosive transfer;

(e) globular transfer

[Q9]

Regardingthe metal transfer modes, choose the relevant one in the word group and enter its

alphabet into each parenthesis.

(1) CO2-shielded arcweldingwithlowcurrents. (a)

(2) Pulsed MAG weldingwithlowaveragecurrents. (a)

(3) CO2-shielded arcweldingwith medium currents. (b)

(4) MAG weldingwithhighcurrentsand a mixedshielding gas of 80%Ar+20%CO2. (a)(5) MIG weldingwithhighcurrents. (c)

[Word group]

(a) short-circuiting transfer (b) globular transfer

(c) spray transfer (d) explosive transfer

8/12/2019 Tugas 02-1106068245

6/12


[Q10]

The followingsentencesaredescribingelectrodewiremeltingand metal transfer modesin MAG

weldingwith solid wire. Choose the relevant one and circle its alphabet.

(1) Wiremeltingrateisgivenmainlybytheheatfromthearcandalsothefollowingdueto The

currentflowinthewire.

(a) Electromagneticforce

(b) Radiationheat

(c) Resistanceheat

(d)Convectionheat

(2) Whenthewiremeltingrate (orwirefeedingspeed) iskeptconstant,

weldingcurrentmaychangeifthefollowing parameter ischanged.

(a) Torchangle

(b) Wireextension

(c) Weldingspeed

(d) Flowrate of shielding gas

(3) In MAG weldingusing 100 % CO2 gas for shielding gas, whenhigherarcvoltageisapplied,

thearcisbecomingunstable. In thatcaseatlowerweldingcurrent, usuallythefollowing metal transfermode isadoptedatlowerarcvoltage.

(a) Short circuiting transfer (Dip transfer)

(b) Globular transfer

(c) Spray transfer

(d) Explosive transfer

(4) In MAG weldingwith Argon basemixtureshielding gas (Ar + CO2) spray transfer mode

maybeobtainedbyincreasingthefollowing parameter morethan a certaincriticalvalue.

(a) Arcvoltage

(b) Weldingcurrent

(c) Wireextension

(d) Flowrate of shielding gas

8/12/2019 Tugas 02-1106068245

7/12


(5) In spray transfer mode, theforcewhichactstodetachthedropletfromthewire tip ismainlythe

following.

(a) Plasma stream

(b) Surfacetension of droplet

(c) Stiffness of thearc

(d) Electric magneticforce

[Q11]

Pick out a non consumable electrode gas-shielded arc welding process using DC power source

with constant current characteristics. And then give the kind of shielding gas, the material of

electrode and the polarity of electrode, when the process is applied on welding of stainless steel.

Jawab:

[Q12]

Pick out at least three (3) advantages and three (3) disadvantages of TIG arc welding process

Jawab:

Keuntungan:

1. Hasi lasanya memiliki kualitas tinggi dan presisi2. Ketika pengelasan tidak terdapat asap dan sparter3. Hasil lasannya bersih karena tidak ada fluks atau slag

Kerugian:

1. Efisiensi panasnya rendah2. Kecepatan las lambatdan deposisi rendah3. Peralatannya mahal dibandingkan dengan SMAW

Welding process ( TIG = Tungsten Inert Gas )

Shielding gas ( Gas Argon )

Material of electrode ( Tungsten )

Polarity of electrode ( DCEN )

8/12/2019 Tugas 02-1106068245

8/12


[Q13]

Give four (4) advantages and four (4) disadvantages of SAW, comparing with the SMAW

(Manual metal arc welding).

Jawab:

SAW

Keuntungan:

1. Penghilangan slag mudah2. Sedikit asap dalam prosesnya3. Kualitas peforma yang baik4. Kecepatan dalam memproduksi tinggi dengan distorsi rendah5. Kedalaman penetrasi baik dengan sedikit grooves

Kerugian:

1. Biayanya mahal2. Metode ini terbatas hanya untuk Karbon, Low Alloy, Stainless Steel dan Nickel Alloy3. Slag harus dibersihkan sebelum dan sesudah pengelasan untuk mengurangi bahaya

inklusi slag

4. Susah diaplikasikan ditempat, karena peralatan yang kompleksSMAW

Keuntungan:

1. Peralatan simple, murah dan portable2. Prosesnyadapatdigunakan untuk berbagai posisi las3. Digunakan untuk repair di workshop, sambungan pipa saluran, konstruksi bangunan

Kelemahan:

1. Kecepatan depositnya rendah karena keterbatasan panjang kawat las dan adanyaterak/slag

2. Lasan tidak terproteksi dari atmosfer secara baik3. Lasan lebih banyak terjadi inklusi /pengotor dibandingkan proses pengelasan lain4. Menghasilkan slag

8/12/2019 Tugas 02-1106068245

9/12


[Q14]

Pick out five (5) features of submerged arc welding process, comparing to manual metal arc

welding (shielded metal arc welding) process.

Jawab:

SAW

1. Mampu menghasilkan single weld pada plat tebal > 1 inch dengan posisi datar2. Arus yang digunakan hingga 2000 A dengan sumber AC atau DC3. Welding automatic atau semi-automatic4. Flux berbentuk serbuk5. Proses cepatSMAW

1. Peralatan simple, murahdan portable2. Prosesnya dapat digunakan untuk berbagai posisi las3. Digunakan untuk repair di workshop, sambungan pipa saluran, konstruksi baguna4. Flux berada di elektrode bersama filler5.

Welding manual

[Q15]

The sentences below, describing MAG welding, have error(s) in the parentheses. Correct them.

(1) In the case of shielding gas containing argon mixed with 20% of CO2 gas, the metal transfer

mode become spray transfer (when the welding speed is higher than a certain critical value).

(2) Comparing with 100% CO2 gas shielded arc welding under the same welding parameters,

MAG welding with using mixed gas of 80% argon and 20% of CO2 has (wider bead, but easily

gets more spatter).

8/12/2019 Tugas 02-1106068245

10/12


[Q16]

Pick out at least three (3) features of TIG welding (GTAW), comparing with MMA welding

(SMAW).

Jawab:

SMAW

Peralatan simple, murah, dan portable. Prosesnya dapat digunakan untuk berbagai posisi las. Digunakan untuk repair di workshop, sambungan pipa, saluran (pipeline), konstruksi

bangunan (kapal, dll).

TIG

Elektrodanya tidak meleleh karena terbuat dari tungsten (wolfram:nonconsumable). Kawat pengisi (filler metal) diumpan secara manual atau mesin. Busur listrik (arc) terbentuk antara elektroda tungsten & kawat las (weld pool). Menggunakan gas sebagai pelindung dan tanpa tekanan (pressure)

[Q17]

Pick out three (3) advantages and three (3) disadvantages of MAG welding comparing to SAW

(submerged arc welding) respectively.

Jawab:

MAG

Keuntungan:

Produktivitas tinggi karena otomatis Dapat diaplikasikan untuk semua posisi Elektrodanya tidak terputus (kontinu) Penggunaannya sangat luas Wide range of application

Kerugian:

Penyatuannya kurang Perlindungan langsung

8/12/2019 Tugas 02-1106068245

11/12

8/12/2019 Tugas 02-1106068245

12/12


Potential untuk gas marks High radiated heat Menghasilkan slag

MAG

Keuntungan:

Produktivitas tinggi karena otomatis Dapat diaplikasikan untuk semua posisi Elektrodanya tidak terputus (kontinu) Penggunaannya sangat luas Wide range of application

Kerugian:

Penyatuannya kurang Perlindungan langsung Peralatannya kompleks Tidak portable

tugas 02-1106068245

Documents