BRAZING SOLDERING AND ADHESIVE BONDING CHAPTER 31 Chapter

BRAZING, SOLDERING, AND ADHESIVE BONDING (CHAPTER 31)

Chapter Overview This chapter considers three joining processes that are similar to welding in certain respects: Brazing, Soldering, and Adhesive Bonding Brazing Soldering • Brazed Joints • Filler Metals and Fluxes • Brazing Methods • Joint Designs in Soldering • Solders and Fluxes • Soldering Methods Adhesive Bonding • Joint Design • Adhesive Types • Adhesive Application Technology Advantages and Disadvantages of Each Process

Brazing Ø Ø Is a joining process in which a filler metal is melted and distributed by capillary action between the faying surfaces of the metal parts being joined No melting of the base metal occurs Only the filler melts Filler metal (brazing metal) has a melting temperature above 450° C but below the melting point of the base metal to be joined

Brazed Joints � � � Two common types: butt and lap joints Been adapted for the brazing process Lap joints more widely used since they provide large interface between parts Clearance between mating surfaces of base parts is important as must be large enough as not to restrict molten filler metal Typical brazing clearances at brazing temperature is . 025 -. 25 mm Cleanliness of the joint surface prior to brazing is important – must be free of oxides, oils, & other contaminants to promote wetting & capillary attraction

Filler Metals and Fluxes � � Common filler metals: aluminum silicon, copper and phosphorous, copper & zinc, gold & silver, nickel alloys, silver alloys Qualifications for brazing metals � Melting temperature must be compatible with base metal � Surface tension in liquid phase must be low for good wettability � � � Fluidity of molten metal must be high for penetration into the joint Chemical and physical interactions with the base metal must be avoided The metal must be capable of being brazed into a joint of adequate strength for the application

Brazing Methods Torch Brazing • gfdsdfgfd Furnace Brazing • fdsasdfda Induction Brazing • asdfdsa Resistance Brazing • asdfdsa

Brazing Methods Cont’d Dip Brazing • fdsa Infrared Brazing • fdsa Braze Welding • fdas

Advantages & Disadvantages

Soldering Ø Ø Similar to braising and can be defined as a joining process which a filler metal with a melting point below 450° C is melted and distributed by capillary action between the faying surfaces of the metal parts to be joined No melting of base metal occurs Filler metal wets and combines with base metal to form a metallurgical bond Filler metal is called solder

Joint Designs in Soldering

Solders & Fluxes

Soldering Methods � � � Hand Soldering Wave Soldering Reflow Soldering

Advantages & Disadvantages

Adhesive Bonding

Joint Design

Adhesive Types � � � Natural Adhesives Inorganic Adhesives Synthetic Adhesives

Adhesive Application Technology � � Surface Preparation Application Methods: � Brushing � Flowing � Manual rollers � Silk screening � Spraying � Automatic applicators � Roll coating

Advantages & Disadvantages

References � Groover, M. P. (2010). Fundamentals of modern manufacturing: materials, processes, and systems. Upper Saddle River, N. J. : Prentice Hall.