Soldering & Welding

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2. The word solder comes from the Latin word “solidaire”
meaning ‘to make solid’

3. • Soldering and
brazing were used
more than 5000yrs
ago to make
jewellery.
• Before 1000 B.C
iron was forge
welded for tools,
weapons and armor.

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Process of building up a localised area with
a filler metal or joining two or more metal
components by heating them to a temp
below their solidus temperature and filling
the gap between them using a molten metal
with a liquidus temp. below 450 C.
IF >450 C : BRAZING
Definition:

5. Uses of soldering
● Used during assembling of a bridge
● Building up contact points on inlays and crowns
● For joining wire clasps
● For joining different components of orthodontic
appliances
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9. ➢ Filler metal (Solder)
➢ Flux and Antiflux
➢Heat source
➢Substrate metal (basic metal)
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What all is needed?

10. Solder
● Types
● composition
● Ideal requirement
● Applications
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11. Classification of Solders
Hard solders
● Higher fusion temp.
● Higher strength/hardness
● Resistant to tarnish & corrosion
eg: Ag & Au
Solders
Soft Solders
● Lower fusion temp. (260o c)
● Soft
● Low corrosion resistant.
eg. Pb-Sn Solders
Plumber solders
Soft solder
Electrician’s solder
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12. Composition of solders
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GOLD SOLDER
Gold -65%
Silver -16%
Copper -13%
Zinc -4%
Tin -2%
MP-750-800OC
SILVER SOLDER
Silver -63%
Copper -27%
Zinc -10%
MP-700-730OC
Uses-soldering
st.steel
TURBINE SOLDER
Silver -45%
Copper -25%
Zinc -15%
Cadmium -15%
MP-580-660
Uses-soldering
st.steel
Cr-Co

13. Requirements of solders
● Wetability.
● Flow temperature < than solidus temperature of the
parent metal.
> than the liquidus temperature of
the filler metal.
● No pitting
● Color Compatibility
● Strength
● Tarnish & Corrosion resistance.
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56O C Less

14. ● The solder commonly used in orthodontic practice is
SILVER SOLDER.
● Composition: Silver
Copper
Zinc
Tin and Indium are added to lower the fusion temp-
erature and improve the solderability.
● The temp used for orthodontic silver solder is
6200-6650C
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15. Fluxes
● Latin : ‘flow’
According to their purpose:
Type 1 : Surface Protection.
low temp glass.eg. Borax fluxes
Type 2 : Reducing
oxides like copper oxides.eg. Borax fluxes
Type 3 : Solvent
dissolves the metal oxides.eg. Flouride
fluxes
Most fluxes are a combination of 2 or more of the above
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16. Common fluxes in use
Borax flux
● Powdered borax glass or
Na Paroborate(55%)
● Boric Acid (35%)
● Silica (10%)
Fluoride flux
KF,
Boric acid &
Silica
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Composition

17. Common fluxes in use
Borax flux
Application
Noble metal alloys. Eg.
Gold or silver alloys
Fluoride flux
Base metal Alloys. Eg.
Stainless steel
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18. Various forms of Fluxes
➢Paint on a substrate metal
➢Fused on the filler metal
➢Prefluxed solder
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FLUX
FILLER METAL

19. Antiflux
● A substance that prevents the flow of the molten
solder on areas coated by it.
● e.g. Graphite
Rouge in chloroform
French chalk in alcohol
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20. Heat Source
● Gas air or gas oxygen torch
Fuel used:
Hydrogen
Natural gas
Acetylene
Propane
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21. Zones of a Flame
1. Oxidizing zone [burned
gas]
2. Reducing zone
combustion zone
[oxidizing]
3. Partial combustion zone
[oxidizing]
4. Cold mixing zone
[unburned gas]
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22.
Technical Procedures
✓ Types:
1. Free-hand soldering
2. Investment soldering
3. Furnace soldering
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23. Technique considerations for soldering
The soldering technique involves several critical steps:
1) Cleaning and preparing the surfaces to be joined.
2) Assembling the parts to be joined in the correct or desired position.
3) Preparation and fluxing of the gap surfaces between the parts
4) Maintaining the proper position of the parts during the procedure.
5) Control of the proper temperature.
6) Control of time to ensure adequate flow of the solder and complete
filling of the solder joint

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30. Definition:
Process of fusing two or more metal parts
together through the application of heat or
pressure or both, with or without a filler metal, to
produce a localized union across an interface
between the parts.
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Welding

31. Methods of welding
● Fusion Welding
Arc/gas Welding
Laser Welding (Neodymium)
Cold Welding
● Pressure Welding
Resistance Seam welding
Resistance Spot welding
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36. Study models
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41. acrylization
● Self cure & heat cured acrylic
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