www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

www.indiandentalacademy.com








Late 19th Century
◦ Scientists/engineers apply advances in electricity to
heat and/or join metals (Le Chatelie...
Fusion Welding
Homogeneous
Gas Welding
Electroslag
High Energy Beam
Electric Arc

Pressure Welding

Heterogeneous
Brazing
...


Metallurgical Capacity



Mechanical Soundness

◦ Parent metal will join with the weld metal without
formation of dele...




Base metal is melted
Filler metal may be added
Heat is supplied by various means
◦
◦
◦
◦

Oxyacetylene gas
Electric...
ELECTRODE COATING
CORE WIRE
WELDING ATMOSPHERE

ARC STREAM
ARC POOL
SOLIDIFIED SLAG
PENETRATION
DEPTH
WELD

BASE METAL

ww...






During fusion welding, the molten metal in
the weld “puddle” is susceptible to
oxidation
Must protect weld puddle...


Typical fluxes
◦
◦
◦
◦
◦

SiO2, TiO2, FeO, MgO, Al2O3
Produces a gaseous shield to prevent contamination
Act as scaveng...




Argon, helium, nitrogen, and carbon dioxide
Form a protective envelope around the weld
area
Used in
◦ MIG
◦ TIG
◦ S...




Produce high-quality welds
Used in electron beam welding
Nuclear/special metal applications
◦ Zr, Hf, Ti





Red...





Oxyacetylene Cutting/Welding
Shielded Metal Arc (“Stick”)
Metal Inert Gas (MIG)
Tungsten Inert Gas (TIG)

www.ind...


Flame formed by burning a mix of
acetylene (C2H2) and oxygen
TORCH TIP

Inner Cone: 5000-6300 deg F





2300 deg F

...





An electric arc is generated between a
coated electrode and the parent metal
The coated electrode carries the elec...


Process:

◦ Intense heat at the arc melts the tip of the
electrode
◦ Tiny drops of metal enter the arc stream and are
d...


For materials such as Al or Ti which quickly
form oxide layers, a method to place an inert
atmosphere around the weld p...




Uses a consumable electrode (filler wire made of
the base metal)
Inert gas is typically Argon

CONSUMABLE
ELECTRODE
...





Tungsten electrode acts as a cathode
A plasma is produced between the tungsten cathode and
the base metal which he...
INCREASING DIFFICULTY

FLAT
HORIZONTAL

VERTICAL

OVERHEAD


Undercuts/Overlaps



Grain Growth
◦ A wide T will exist between base metal and HAZ.
Preheating and cooling methods wi...


Inclusions
◦ Impurities or foreign substances which are forced into the weld
puddle during the welding process. Has the...



Rapid heating and cooling results in thermal
stresses detrimental to joint strength.
Prevention

◦ Edge Preparation/A...
BUTT JOINT
FILLET JOINT
STRAP JOINT

LAP JOINT

CORNER JOINT
www.indiandentalacademy.com
FAR SIDE DETAILS

Field weld symbol

Weld Geometry

Electrode
Material

D

L1-L2

D

L1-L2

ARROW SIDE DETAILS

Weld all-a...
Geometry symbol for V-groove
One-sided welds are max 80% efficient
Two sided are 100% efficient
1/2

1/2

1/2”

1/2”

www....
Backing
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
Thank you
www.indiandentalacademy.com
Leader in continuing dental education

www.indiandentalacademy.com
Upcoming SlideShare
Loading in …5
×

Welding /fixed orthodontic courses

662 views
486 views

Published on


The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.


Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078

Published in: Education, Business, Technology
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
662
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
0
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Welding /fixed orthodontic courses

  1. 1. www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3.     Late 19th Century ◦ Scientists/engineers apply advances in electricity to heat and/or join metals (Le Chatelier, Joule, etc.) Early 20th Century ◦ Prior to WWI welding was not trusted as a method to join two metals due to crack issues 1930‟s and 40‟s ◦ Industrial welding gains acceptance and is used extensively in the war effort to build tanks, aircraft, ships, etc. Modern Welding ◦ the nuclear/space age helps bring welding from an art to a science www.indiandentalacademy.com
  4. 4. Fusion Welding Homogeneous Gas Welding Electroslag High Energy Beam Electric Arc Pressure Welding Heterogeneous Brazing Friction Welding Soldering MIG TIG Shielded Metal Arc – “Stick” www.indiandentalacademy.com
  5. 5.  Metallurgical Capacity  Mechanical Soundness ◦ Parent metal will join with the weld metal without formation of deleterious constituents or alloys ◦ Joint will be free from discontinuities, gas porosity, shrinkage, slag, or cracks  Serviceability ◦ Weld is able to perform under varying conditions or service (e.g., extreme temperatures, corrosive environments, fatigue, high pressures, etc.) www.indiandentalacademy.com
  6. 6.    Base metal is melted Filler metal may be added Heat is supplied by various means ◦ ◦ ◦ ◦ Oxyacetylene gas Electric Arc Plasma Arc Laser www.indiandentalacademy.com
  7. 7. ELECTRODE COATING CORE WIRE WELDING ATMOSPHERE ARC STREAM ARC POOL SOLIDIFIED SLAG PENETRATION DEPTH WELD BASE METAL www.indiandentalacademy.com
  8. 8.    During fusion welding, the molten metal in the weld “puddle” is susceptible to oxidation Must protect weld puddle (arc pool) from the atmosphere Methods ◦ Weld Fluxes ◦ Inert Gases ◦ Vacuum www.indiandentalacademy.com
  9. 9.  Typical fluxes ◦ ◦ ◦ ◦ ◦ SiO2, TiO2, FeO, MgO, Al2O3 Produces a gaseous shield to prevent contamination Act as scavengers to reduce oxides Add alloying elements to the weld Influence shape of weld bead during solidification www.indiandentalacademy.com
  10. 10.    Argon, helium, nitrogen, and carbon dioxide Form a protective envelope around the weld area Used in ◦ MIG ◦ TIG ◦ Shield Metal Arc www.indiandentalacademy.com
  11. 11.    Produce high-quality welds Used in electron beam welding Nuclear/special metal applications ◦ Zr, Hf, Ti   Reduces impurities by a factor of 20 versus other methods Expensive and time-consuming www.indiandentalacademy.com
  12. 12.     Oxyacetylene Cutting/Welding Shielded Metal Arc (“Stick”) Metal Inert Gas (MIG) Tungsten Inert Gas (TIG) www.indiandentalacademy.com
  13. 13.  Flame formed by burning a mix of acetylene (C2H2) and oxygen TORCH TIP Inner Cone: 5000-6300 deg F   2300 deg F Combustion Envelope 3800 deg F Fusion of metal is achieved by passing the inner cone of the flame over the metal Oxyacetylene can also be used for cutting metals www.indiandentalacademy.com
  14. 14.    An electric arc is generated between a coated electrode and the parent metal The coated electrode carries the electric current to form the arc, produces a gas to control the atmosphere and provides filler metal for the weld bead Electric current may be AC or DC. If the current is DC, the polarity will affect the weld size and application www.indiandentalacademy.com
  15. 15.  Process: ◦ Intense heat at the arc melts the tip of the electrode ◦ Tiny drops of metal enter the arc stream and are deposited on the parent metal ◦ As molten metal is deposited, a slag forms over the bead which serves as an insulation against air contaminants during cooling ◦ After a weld „pass‟ is allowed the cool, the oxide layer is removed by a chipping hammer and then cleaned with a wirebrush before the next pass. www.indiandentalacademy.com
  16. 16.  For materials such as Al or Ti which quickly form oxide layers, a method to place an inert atmosphere around the weld puddle had to be developed www.indiandentalacademy.com
  17. 17.   Uses a consumable electrode (filler wire made of the base metal) Inert gas is typically Argon CONSUMABLE ELECTRODE DRIVE WHEELS POWER SOURCE SHIELDING GAS BASE METAL ARC COLUMN PUDDLE www.indiandentalacademy.com
  18. 18.    Tungsten electrode acts as a cathode A plasma is produced between the tungsten cathode and the base metal which heats the base metal to its melting point Filler metal can be added to the weld pool TUNGSTEN ELECTRODE POWER SOURCE TUNGSTEN ELECTRODE (CATHODE) ++ SHIELDING GAS BASE METAL --- ARC COLUMN PUDDLE ++ BASE METAL (ANODE) www.indiandentalacademy.com
  19. 19. INCREASING DIFFICULTY FLAT HORIZONTAL VERTICAL OVERHEAD
  20. 20.  Undercuts/Overlaps  Grain Growth ◦ A wide T will exist between base metal and HAZ. Preheating and cooling methods will affect the brittleness of the metal in this region  Blowholes ◦ Are cavities caused by gas entrapment during the solidification of the weld puddle. Prevented by proper weld technique (even temperature and speed) www.indiandentalacademy.com
  21. 21.  Inclusions ◦ Impurities or foreign substances which are forced into the weld puddle during the welding process. Has the same effect as a crack. Prevented by proper technique/cleanliness.  Segregation ◦ Condition where some regions of the metal are enriched with an alloy ingredient and others aren‟t. Can be prevented by proper heat treatment and cooling.  Porosity ◦ The formation of tiny pinholes generated by atmospheric contamination. Prevented by keeping a protective shield over the molten weld puddle. www.indiandentalacademy.com
  22. 22.   Rapid heating and cooling results in thermal stresses detrimental to joint strength. Prevention ◦ Edge Preparation/Alignment – beveled edges and space between components to allow movement ◦ Control of heat input – skip or intermittent weld technique ◦ Preheating – reduces expansion/contraction forces (alloys) and removes moisture from the surface ◦ Peening – help metal stretch as it cools by hitting with a hammer. Use with care since it may work harden the metal ◦ Heat Treatment – “soak” the metal at a high temperature to relieve stresses ◦ Jigs and Fixtures – prevent distortion by holding metal fixed ◦ Number of Passes – the fewerwww.indiandentalacademy.com the better.
  23. 23. BUTT JOINT FILLET JOINT STRAP JOINT LAP JOINT CORNER JOINT www.indiandentalacademy.com
  24. 24. FAR SIDE DETAILS Field weld symbol Weld Geometry Electrode Material D L1-L2 D L1-L2 ARROW SIDE DETAILS Weld all-around for pipes, etc. D = Weld Depth (usually equal to plate thickness) L1 = Weld Length L2 = Distance between centers for stitched welds The Field Weld Symbol is a guide for installation. Shipyards normally do not use it, except in modular construction. www.indiandentalacademy.com
  25. 25. Geometry symbol for V-groove One-sided welds are max 80% efficient Two sided are 100% efficient 1/2 1/2 1/2” 1/2” www.indiandentalacademy.com
  26. 26. Backing www.indiandentalacademy.com
  27. 27. www.indiandentalacademy.com
  28. 28. www.indiandentalacademy.com
  29. 29. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

×