Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 30 Brazing, Soldering, Adhesive, Bonding

Similar presentations

Presentation on theme: "Chapter 30 Brazing, Soldering, Adhesive, Bonding"— Presentation transcript:

1 Chapter 30 Brazing, Soldering, Adhesive, Bonding
& Mechanical Fastening process Chapter 30

2 Brazing Joining process
A filler metal is placed between two workpieces and heated until melted Two main types of Brazing Ordinary Braze welding Use of flux is very important

3 Fig: a) Brazing b) Braze welding operation
Filler Metals Available in a wide range of brazing temperatures They come in a wide range of shapes Choice of the filler metal and its composition are important Diffusion of the filler metal in to the workpeice is an important consideration Fig: a) Brazing b) Braze welding operation

4 Fluxes The use of flux in brazing is very important Generally made of:
Borax Boric acid Borates Fluorides Chlorides Wetting agents may also be added

5 Brazing Methods Torch Brazing
Performed by heating the joint with a torch Depositing the filler metal in the joint Suitable part thickness (0.25 – 6.0)mm Not a automated process More than one torch can be used in this process

6 Brazing Methods Furnace Brazing
Precleaned & Preloaded with brazing metal Heated in a furnace Fig:An example of furnace brazing a)before b) after

7 Other Types Of Brazing Induction Brazing Resistance Brazing
Dip Brazing Infrared Brazing Diffusion Brazing

8 Braze Welding Prepared like fusion welding
Filler metal is deposited at the joint with the use of an oxyacetylene torch Considerably more filler is used Temperature is minimal compared to that of fusion welding; part distortion is minimal

9 Brazing Process Capabilities
Dissimilar metals can be assembled with good joint strength Shear strength of brazed joints can reach 800Mpa Fig:Joint Designs commonly used in brazing operations.The clearance between the two parts being brazed is an important factor in joint strength.If the clearance is to small, the molten braze metal will not fully penetrate the interface.

10 Good/Poor Designs

11 Soldering Different types of soldering Torch Furnace Iron Induction
Resistance Dip Infrared Ultrasonic reflow (paste) Wave

12 Reflow Soldering Solvents present in the paste are evaporated
The Flux in the paste is activated and the fluxing action occurs The components are carefully preheated The solder particles are melted and wet the joint The assembly is cooled

13 Wave Soldering Popular approach to attaching circuits to circuit boards Fig: a)Screening or stenciling paste onto a printed circuit board: 1) Stenciling process 2) a section of a typical stencil pattern b) wave soldering process

14 Types Of Fluxes Inorganic acids or salts – clean the surface rapidly
Noncorrosive resin-based – used in electrical applications Soldering is used extensively in electronics industry

15 Adhesive Bonding Products are joined and assembled by the use of Adhesives Adhesives properties to be considered Strength Toughness Resistance to various fluids Ability to wet the surface to be bonded

16 Types of adhesives Surface must be clean for joining parts
Should avoid joints that might be subjected to peeling forces Design for adhesive bonding

17 Adhesive Peeling Test Fig : Characteristic behavior of (a) brittle (b) tough adhesive in a peeling test

18 Joint Design in Adhesive Bonding
Fig:Various joint design in adhesive bonding.

19 Configurations for adhesive bonds
Fig : (a) single lap (b) double lap (c) scarf (d) strap

20 Mechanical Fastening Threaded Fasters Other Fastening Methods Bolts
Screws Nuts Other Fastening Methods Stapling Crimping Snap-in Fasteners Shrink and press fits

21 Fig:a)solid b)tubular c) split (bifurcated) d) compression
Rivets Fig:a)solid b)tubular c) split (bifurcated) d) compression Fig : Design guidelines for riveting (a)Exposed shank is too long; the result is buckling instead of upsetting (b)Rivets should be placed sufficiently far from edges to avoid stress concentrations (c)Joined sections should allow ample clearance for riveting tools (d) section curvature should not interfere with the riveting process

22 Joining Plastics Heat softens the plastic to a molten state
Then pressure added & fusion takes place External Heat Sources Hot air Heated tools & dies Electrical-Resistance Lasers Internal Heat Sources Ultrasonic welding Friction welding


Download ppt "Chapter 30 Brazing, Soldering, Adhesive, Bonding"

Similar presentations

Ads by Google