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![ANTI FLUX
■ Materials used to restrict flow of solder are known as anti
flux. It is applied on the surface of specific area where
the solder should not flow into. It is applied before
applying flux or solder.
1. Zinc oxide in alcohol
2. Rouge (iron oxide)in chloroform
3. Whiting [calcium carbonate] in an alcohol and water suspension
4. Graphite](https://image.slidesharecdn.com/solderingandwelding-250204045049-75aa605d/75/Soldering-and-welding-in-orthodontic-dental-practice-17-2048.jpg)
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Soldering and welding in orthodontic dental practice
- 1.
- 3. ■ It isnot always possible to create a metal device in one piece, such as by casting, ■ So it becomes necessary to assemble it from separately prepared parts.
- 4.
- 5. ■ In dentistry,the fabrication techniques used are either soldering or welding.
- 6. Metal Joining Procedures ■Are divided into three categories • SOLDERING • BRAZING • WELDING
- 7. SOLDERING ■ SOLDERING: It’sdefined as the joining of metals by the fusion of filler metal between them, at a temperature below the solidus temperature of the metals being joined and below 450°C
- 8. ■ SOLIDUS TEMPERATURE:the temperature at which metals of an alloy system become completely solidified on cooling or start to melt on heating.
- 9. ■ The solderingprocess involves 1. the substrate or parent metals to be joined 2. soldering filler metal (called solder) 3. a flux 4. a heat source.
- 10. SUBSTRATE METAL ■ Thesubstrate (basic) metal is the original pure metal or alloy that is prepared for joining to another substrate metal or alloy. ■ This substrate metal’s composition may vary mildly from gold based alloys to base metal alloys.
- 11. ■ The compositionof the substrate metal determines its melting range. ■ The composition determines the oxide that forms on the surface during heating. ■ The composition of the substrate metal determines the wettability of the substrate by the molten solder alloy.
- 12. FLUX ■ In latinflux means flow. ■ It is a material used to prevent the formation of or to dissolve and facilitate removal of, oxides and other undesirable substances that may reduce the quality or strength of the metal structure.
- 13. ■ CLASSIFICATION OFFLUX :- 1. According to their primary purpose/activity. Type I : Surface protective – This type covers the metal surface and prevents access to oxygen so that no oxides can form. Type II: Reducing agent – This type reduces any oxides present and exposes clean metal. Type III: Solvent – This type of flux dissolves any oxides present.
- 14. 2. According totheir composition ■ Borax fluxes ■ Fluoride fluxes 3. According to the pH of the flux ■ Acidic fluxes – SiO2 ■ Basicfluxes – CaO, lime ■ Neutral – Fluorspar (Ca.F2), Borax (Na2B4O2)
- 15. ■ APPLICATION OFFLUX 1. Painted on to the substrate metal at the junction of pieces to be joined. 2. Fused on to the surface of the filler metal strip. 3. Prefluxed solders :- Solder available in a tube form with flux contained inside the tube.
- 16. IDEAL REQUIREMENTS OFA FLUX: ■ Assist in the free flow of solder and permits the solder to wet and spread over the metal surface. ■ Must have a fusion temperature below that alloy that is being heated, and at the sametime, it should not burn or volatalize readily.
- 17. ANTI FLUX ■ Materialsused to restrict flow of solder are known as anti flux. It is applied on the surface of specific area where the solder should not flow into. It is applied before applying flux or solder. 1. Zinc oxide in alcohol 2. Rouge (iron oxide)in chloroform 3. Whiting [calcium carbonate] in an alcohol and water suspension 4. Graphite
- 18. FILLER METAL/SOLDER ■ Fusiblealloy or metal which is used to join two pieces of metal during soldering operation . ■ The filler metal in brazing is called “spelter” the term which is not used in dentistry .
- 19. Qualities of anideal solder 1. Ease of flow at relatively low temperature. 2. Sufficient fluidity to freely flow when melted. 3. Ability to wet substrate metal. 4. Strength compatible with that of the structure being joined. 5. Resistance to tarnish and corrosion. 6. Acceptable colour to give an inconspicuous joint. 7. Resistance to pitting during heating.
- 20. CLASSIFICATION OF SOLDERS I.Soft solders Hard solders II. Precious metal solders Non precious metal solders
- 21. Silver solders ■ Usedin orthodontic appliances ■ They are low fusing –fusion temp-600-750°C ■ Used with stainless steel or other base metal alloys ■ Resistance to tarnish and corrosion is not as good as gold solders ■ But have strength comparable to gold solders
- 22. Composition -Silver -10-80% -Copper -15-30% -Zinc -4-35% -Small amounts of cadmium, tin and phosphorus.
- 24. TYPES OF SOLDERING I.On the basis of type of solder use ■ Soft soldering ■ Hard soldering II. On the basis of method of heating ■ Torch soldering ■ Dip soldering ■ Furnace soldering
- 25. III. On thebasis of technique used to assemble the dental appliances ■ Free hand soldering ■ Investment soldering
- 26. ■ STEPS INSOLDERING: 1. Cleaning the surfaces to be joined 2. Assembling the parts to be joined 3. Selecting the right solder and flux 4. Selection of a proper joint 5. Application of flux 6. Heating and introduction of solder 7. Quenching
- 27. ■ SOLDERING FAILURES Are due to: Failure to clean the parts to be joined. Improper fluxing Poor flow of solder Over heating of the solder can lead to pitted joint of low strength
- 28. ■ BRAZING: Brazingis defined as joining of metals by the fusion of a filler metal between them, at a temperature below the solidus temperature of metals being joined and above 450°C.
- 29. ■ WELDING: Thejoining of two or more metal parts by applying heat, pressure or both, without a filler metal, to produce localized union across the interface through fusion or diffusion.
- 30. TYPES OF WELDING I.•Fusion or Non-pressure welding •Plastic or pressure welding II. •Gas welding •Plasma welding •Laser welding III. •Spot welding •Pressure welding •Seam welding •Projection welding
- 31. SPOT WELDING: ■ Itis the type of welding most commonly used in the construction of orthodontic appliances. ■ PRINCIPLE: Spot welding is based on principle of heat and electric resistance i.e. when an electric current experiences resistance,heat is generated.
- 32. ■ H I2 RT Where H = Heat in joules I = Current in amperes R = Resistant in ohms T = time in seconds ■ Welds are made by passing an electric current through the pieces to be joined which are simultaneously pressed together. The current heats the metal which becomes plastic and the pressure forges the softened metals into a single piece.
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