Soldering Brazing and Braze Welding - PowerPoint PPT Presentation

About This Presentation
Title:

Soldering Brazing and Braze Welding

Description:

... Brazing steps are the same except for Brazing filler metal s ... be joined Speed of joining Less chance of damaging parts ... process Temperature control ... – PowerPoint PPT presentation

Number of Views:841
Avg rating:3.0/5.0
Slides: 33
Provided by: mmt2
Learn more at: https://spot.pcc.edu
Category:

less

Transcript and Presenter's Notes

Title: Soldering Brazing and Braze Welding


1
SolderingBrazingand Braze Welding
2
Objectives
  • Define the terms soldering, brazing, and braze
    welding
  • Advantages and disadvantages of liquid-solid
    phase bonding
  • Properly clean, assemble, and perform required
    practice joints
  • Functions of fluxes in making proper liquid-solid
    phase bonded joints

3
Introduction
  • Soldering and brazing are classified by the AWS
    as liquid-solid phase bonding processes
  • Base material stays solid and filler material is
    liquid
  • Hot Gluing
  • Phase is the temperature at which bonding takes
    place
  • Soldering and brazing differ
  • Soldering takes place below 840 Fahrenheit
  • FAA says its 800F?????????????????????
  • Capillary action is the force that pulls water up
    into a paper towel
  • Braze welding does not need capillary action

4
Soldering/Brazing Applications
  • Steps in Sweat Soldering
  • 1) Copper pipe is cleaned
  • 2) Flux is applied
  • 3) Heat is applied
  • 4) Solder is added
  • 5) Solder is drawn into fitting via heat
    (capillary Action)
  • 6) Pipe is wiped cleaned
  • 7) Brazing steps are the same except for Brazing
    filler metal s added instead of solder.

5
Braze Welding
  • Steps in Braze Welding
  • 1) Base material is cleaned
  • 2) Flux is applied
  • 3) Heat is applied
  • 4) Braze is added
  • 5) Braze material is added into a joint.
    Capillary Action is not used.
  • 6) Post Braze weld is cleaned

6
Figure 31-2 Capillary action pulls water into a
thin tube.
7
Advantages of Soldering and Brazing
  • Some advantages of soldering and brazing
  • Low temperature
  • Permanently or temporarily joined
  • Dissimilar materials can be joined
  • Speed of joining
  • Less chance of damaging parts
  • Slow rate of heating and cooling
  • Parts of varying thicknesses can be joined
  • Easy realignment
  • Disadvantage
  • Service Temp!!!!!!!!!!!!!!!!!

8
Mechanical Properties
9
Tensile and Shear Strength
  • Tensile strength of a joint is its ability to
    withstand being pulled apart
  • Brazed joints have a tensile strength 4-5 times
    higher than the filler metal itself
  • As joint spacing decreases, surface tension
    increases the tensile strength
  • Shear strength is ability of a joint to withstand
    a force parallel to the joint
  • For a solder or braze joint, the shear strength
    depends upon the amount of overlapping area
  • The greater the area overlapped, the greater the
    strength

10
Ductility
  • Ductility is the ability of a metal to
    plastically deform without breaking or
    fracturing, with the cohesion between the
    molecules remaining sufficient to hold them
    together to bend without failing.
  • Most soldering and brazing alloys are ductile
    metals

11
Fatigue Resistance
  • Fatigue resistance is the ability to be bent
    repeatedly without exceeding the elastic limit
  • Elastic Limit
  • Plastic Limit
  • For most soldering or brazing joints, fatigue
    resistance is low
  • Fatigue failures may occur as a result of
    vibration and/or cycles of load.

12
Fluxes
  • Fluxes used in soldering and brazing have three
    major functions
  • Remove oxides that result from heating parts
  • Promote wetting
  • Aid in capillary action (if soldering or brazing)
  • Flux must be thin, when heated to its reacting
    temperature
  • Fluxes are available in many forms
  • Paste
  • Liquid
  • Powder

13
Soldering and Brazing Methods
  • Grouped according to method of applying heat
  • Torch (TB)
  • Furnace
  • Induction
  • Dip

14
Torch Soldering and Torch Brazing
  • Advantages of using a torch
  • Versatility
  • Portability
  • Speed
  • Disadvantages of using a torch
  • Overheating
  • Skill
  • Fires

15
Furnace Soldering and Brazing
  • Advantages of using a furnace
  • Furnace brazing is a semi-automatic process
  • Temperature control
  • Controlled atmosphere (Common atmospheres used
    include inert, reducing or vacuum atmospheres
    all of which protect the part from oxidation)
  • Uniform heating
  • Mass production
  • Disadvantages of using a furnace
  • Size
  • Heat damage

16
Figure 31-20 Furnace brazing permits the rapid
joining of parts on a production basis.
17
Induction Soldering and Brazing
  • Induction heating is the process of heating an
    electrically conducting object (usually a metal)
    by electromagnetic induction, where eddy currents
    (also called Foucault currents) are generated
    within the metal and resistance leads to Joule
    heating of the metal.
  • Advantage of the induction method is speed
  • Disadvantages of the induction method
  • Distortion
  • Lack of temperature control
  • Incomplete penetration

18
Dip Soldering and Brazing
  • The parts to be joined are fixtured and the
    brazing compound applied to the mating surfaces,
    typically in slurry form. Then the assemblies are
    dipped into a bath of molten salt (typically
    NaCl, KCl and other compounds) which functions
    both as heat transfer medium and flux.
  • Advantages of dip processing
  • Mass production
  • Corrosion protection
  • Distortion minimized
  • Disadvantages of dip processing
  • Steam explosions
  • Corrosion
  • Size
  • Quantity

19
Filler Metals
  • Should be selected by considering as many of the
    criteria as possible
  • Welders decide most important criteria
  • Soldering and brazing metals are alloys

20
Figure 31-27 Solder being shaped as it cools to
its paste range.
21
Soldering Alloys
  • Usually identified by their major alloying
    elements
  • Base metal can be joined by more than one solder
    alloy

22
Tin-lead
  • Most popular solder
  • Least expensive
  • Most commonly used on electrical connections
  • Never used for water piping

23
Brazing Alloys
  • The AWS 's classification system for brazing
    alloys uses the letter B
  • Next series of letters indicate the atomic symbol
    of metals used
  • Not all available brazing alloys have an AWS
    classification
  • Some special alloys are known by their trade names

24
Copper-zinc
  • Most popular brazing alloys
  • Available as regular and low-fuming alloys
  • Tendency to burn out when overheated
  • If breathed in, it can cause zinc poisoning
  • If you think you have zinc poisoning, get medical
    treatment immediately

25
Copper-zinc and Copper-phosphorus A5.8
  • Known as brazing rods
  • Referred to as phos-copper
  • Vast differences among the five classifications
  • Five classifications of copper-zinc filler rods
  • BRCuZn
  • BRCuZn-A
  • BRCuZn-B
  • BRCuZn-C
  • BRCuZn-D
  • If overheated will cause zinc fumes

26
Joint Design
  • Spacing between parts being joined greatly
    affects tensile strength
  • Strongest joints are obtained when parts use lap
    or scarf joints
  • Some joints can be designed so that the flux and
    filler metal may be preplaced
  • Joint preparation is very important

27
Figure 31-28 The joining area should be three
times the thickness of the thinnest joint member.
28
Building up Surfaces and Filling Holes
  • Surfaces on worn parts are built up again with
    braze metal
  • Ideal for parts that receive limited abrasive
    wear
  • Braze buildup has no hard spots
  • Good for flat and round stock
  • Holes in light-gauge metal can be filled using
    braze metal

29
Figure 31-51 When building up a surface,
alternate the direction of each layer.
30
Silver Brazing
  • Melting temperature for alloys is around 1400
    Fahrenheit
  • Copper pipe glows a dull red
  • Best types of flame to use
  • Air acetylene
  • Air MAPP
  • Air propane
  • Any air fuel-gas mixture

31
Soldering
  • Practices use tin-lead or tin-antimony solders
  • Both have low melting temperature
  • Best type of flame
  • Air acetylene
  • Air MAPP
  • Air propane
  • Any fuel-gas mixture

32
Summary
  • Brazing and soldering have many advantages
  • Very versatile
  • Ability to join many different materials with a
    limited variety of fluxes and filler metals
  • Soldering can be permanent or temporary
  • Be creative in the way you apply these processes
Write a Comment
User Comments (0)
About PowerShow.com