welding tech special machine

1. SSW process uses heat and pressure, usually in a controlled atmosphere, with
sufficient time for diffusion and coalescence to occur
•Temperatures  0.5 Tm
•Plastic deformation at surfaces is minimal
•Primary coalescence mechanism is solid state diffusion
•Limitation: time required for diffusion can range from seconds to hours
DIFFUSION WELDING (DFW)
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2. •Joining of high-strength and refractory metals in aerospace and nuclear industries
•Can be used to join either similar and dissimilar metals
•For joining dissimilar metals, a filler layer of different metal is often sandwiched between
base metals to promote diffusion
DFW APPLICATIONS
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3. SSW process in which rapid coalescence of two metallic surfaces is caused by
the energy of a detonated explosive
•No filler metal used
•No external heat applied
•No diffusion occurs - time is too short
•Bonding is metallurgical, combined with mechanical interlocking that results
from a rippled or wavy interface between the metals
EXPLOSION WELDING (EXW)
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4. Commonly used to bond two dissimilar metals, in particular to clad one
metal on top of a base metal over large areas.
Explosive Welding
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5. •Commonly used to bond two dissimilar metals, e.g., to clad one metal
on top of a base metal over large areas
•(1) Setup in parallel configuration, and (2) during detonation of the
explosive charge
EXPLOSIVE WELDING
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6. SSW process in which coalescence is achieved by frictional heat combined
with pressure
•When properly carried out, no melting occurs at faying surfaces
•No filler metal, flux, or shielding gases normally used
•Process yields a narrow HAZ
•Can be used to join dissimilar metals
•Widely used commercial process, amenable to automation and mass
production
FRICTION WELDING (FRW)
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7. •(1) Rotating part, no contact; (2) parts brought into contact to
generate friction heat; (3) rotation stopped and axial pressure applied;
and (4) weld created
Friction Welding
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8. Applications:
•Shafts and tubular parts
•Industries: automotive, aircraft, farm equipment, petroleum and natural
gas
Limitations:
•At least one of the parts must be rotational
•Flash must usually be removed (extra operation)
•Upsetting reduces the part lengths (which must be taken into
consideration in product design)
APPLICATIONS AND LIMITATIONS OF
FRICTION WELDING
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9. •(a) General setup for a lap joint; and (b) close-up of weld area
Ultrasonic Welding
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10. •Wire terminations and splicing in electrical and electronics industry
•Eliminates need for soldering
•Assembly of aluminum sheet metal panels
•Welding of tubes to sheets in solar panels
•Assembly of small parts in automotive industry
USW APPLICATIONS
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11. ERW & High Frequency Welding
Lesson Objectives
When you finish this lesson you will understand:
• The difference between low frequency Electric
Resistance Welding and High Frequency Welding
• Applications of each
Learning Activities
1. View Slides;
2. Read Notes,
3. Listen to lecture
4. Do on-line workbook
5. Do Homework
Keywords
Electric Resistance Welding, High Frequency Welding, Tube Welding, Proximity Conductor,
Induction Coil, Induction Current, Impeder, Seam Annealing
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12. Appreciating Hig-Frequency Welding
Welding Journal, July 1996
High Frequency
Induction Welding
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13. Metals Handbook, Vol 6
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14. Impeder Inside the Core
Promotes Path ADC
Linnert, Welding Metallurgy
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15. [Reference: Welding Handbook, Volume 2, p.653, AWS]
Tube Butt SeamTube Butt Seam Tube Mash Seam
HF
HF
HF
Induction Coil
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16. Strip Butt T-Joint
Spiral Tube
Spiral Tube Fin
HF
HF
HF
HF
[Reference: Welding Handbook, Volume 2, p.653, AWS]
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17. Projection Seam
Pipe Butt Bar Butt
HF
HF
HF
Induction
Coil
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18. AWS Welding Handbook
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19. Typical Tube Welding Conditions for Steels
30 m/min (100 ft/min)at:
600 kW power for
12 mm-wall (1/2 in);
diameter of 200 - 1200 mm (8 - 48 in)
60 -240 m/min (200-800 ft/min)
100-400kW power
0.6 - 1.6 mm walls (0.025 - 0.065 in)
diameter of 25 - 50 mm (1 - 2 in)
Note high speed
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20. AWS Welding Handbook
Induction Coils
• Cu Tubing or Bar
• Normally water cooled
• Surround = efficiency
• Mag. Strength reduces with distance =
1/8 - 1 inch between coil and work
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21. Produce welds with very narrow heat-affected zones
High welding speed and low-power consumption
Able to weld very thin wall tubes
Adaptable to many metals
Minimize oxidation and discoloration as well as distortion
High efficiency
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22. Special care must be taken to avoid radiation interference in the plant’s vicinity
Uneconomical for products required in small quantities
Need the proper fit-up
Hazards of high-frequency current
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23. Examples of a few products that can be fabricated by high-frequency welding are shown in
the above slide.
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24. LIGHT AMPLIFICATION by STIMULATED EMISSION of
RADIATION.
Coalescence of heat is produced by the Laser beam which is having high
energy.
Concentrated heat source.
Allowing for narrow, deep welds.
High welding rates.
Frequently used in high volume applications.
LASER BEAM WELDING
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25. 8 / 6 / 2 0 1 8
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26. High power density (1 Mw/cm²)) resulting in small HAZ and
high heating and cooling rates.
The spot size vary (0.2 mm and 13 mm), though only smaller
sizes are used for welding.
The penetration is proportional to power supplied & focal
point.
Maximum penetration when focal point is slightly below the
surface
Milliseconds long pulses are used to weld thin materials such as
razor blades.
Continuous laser systems are employed for deep welds.
High power capability of gas laser make it suitable for high
volume applications.
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27. 8 / 6 / 2 0 1 8
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28. LASER GENERATION
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29. TYPICAL WORK PIECE
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30. Combines LBW with an arc welding.
It allows for greater positioning flexibility.
Arc supplies molten metal to fill the joint, and due to the use
of a laser, increases the welding speed .
Weld quality tends to be higher as well as potential for
undercutting is reduced.
LASER HYBRID WELDING
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31. Operate at wavelengths of order 1 µm, hence special
protection to prevent Retina damage.
Pulsed Laser- Ruby Laser, Neodymium Glass
Continuous Laser- Neodymium Yttrium Aluminum
Garnet (Nd YAG)
Pulse Duration- 1/1,000,000,000 second - 2 milliseconds
Efficiency= 1-10 %
SOLID LASER
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32. Power output:-
Ruby lasers = 10–20 W
Nd:YAG laser = 0.04–6,000 W
Fiber optics is used.
Popular design is a single crystal rod of 20 mm diameter and 200 mm long, ground
flat ends.
Disk shaped crystals are growing in popularity
flashlamps are giving way to diodes due to their high efficiency
SOLID LASER CONT……
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33. Uses high-voltage, low-current power sources.
Both continuous and pulsed mode.
Wavelength of the laser beam is of order 10.6 μm.
Fiber optics absorbs these wavelength & get destroyed.
Rigid lens and mirror delivery system is used.
Power outputs for gas lasers can be much higher than solid-state
lasers, reaching 25 kw.
GAS LASER
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34. CO2 + He +N22 in glass tube
N2 acts as intermediary between electrical & vibration energy.
He cools for re excitation.
Efficiency= 20%
GAS LASER CONT…..
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35. Energy density= 10^6 w/ mm²
Power= 20 kw (1000w/ mm3 /min)
Wavelength= 1-10 micron
Weld thickness= upto 25mm (keyhole)
Welding speed- 25-250 mm/min
SPECIFICATION
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36. Five axis laser control
Excellent performance
Processes high alloyed metals.
Open atmospheric operation
Narrow HAZ
Low thermal inputs.
No filler/flux is needed
Easily welds dissimilar metals
Extreme precise operation
ADVANTAGE
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37. Low weld distortion.
Fast in terms of cost effictive
Very small welding spot
Weld inside transparent media like glass etc.
Permits welding of small & closly spaced components of few micron
size
Welds electric insulators.
Can be easily focused to microscopic dimension.
visibility
ADVANTAGE CONT…..
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38. Rapid cooling rates may cause cracking
High capital cost
Optical surface easily damaged
High maintenance & setup cost
Controlled process to limit its adverse effects
Low welding speed
Limited to depth of 1.5 mm without defects like blow holes & porosity.
DISADVANTAGE
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39. Electronic, Automotive & food processing
Spot welds
Vacuum components are welded easily
Medical equipment
Carbon steels & ferrous materials are welded
Ideal for automation & robotics
Used to weld IC to plates
In aircraft industry to weld light gauge marerials
Cu, Ni, Al, Ss, W, Ti, Zr, Ta Colunium etc
Wire to wire, sheet to sheet, tube to sheet & small diameter stud welds.
APPLICATIONS
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41. Electron beam welding8 / 6 / 2 0 1 8
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43. Electron Beam Welding (EBW)
Electron Beam Welding is a welding process utilizing a heat generated by a beam of high energy electrons. The
electrons strike the work piece and their kinetic energy converts into thermal energy heating the metal so that the edges
of work piece are fused and joined together forming a weld after Solidification.
The process is carried out in a vacuum chamber at a pressure of about 2*10-7 to 2*10-6 psi (0.00013 to 0.0013 Pa).
Such high vacuum is required in order to prevent loss of the electrons energy in collisions with air molecules.
The electrons are emitted by a cathode (electron gun). Due to a high voltage (about 150 kV) applied between the
cathode and the anode the electrons are accelerated up to 30% - 60% of the speed of light. Kinetic energy of the
electrons becoms sufficient for melting the targeted weld. Some of the electrons energy transforms into X-ray irradiation
Electrons accelerated by electric field are then focused into a thin beam in the focusing coil. Deflection coil moves the
elctron beam along the weld.
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44. Electron Beam is capable to weld work pieces with thickness from 0.0004” (0.01 mm) up to 6” (150 mm) of
steel and up to 20” (500 mm) of aluminum. Electron Beam Welding may be used for joining any metals
including metals, which are hardly weldable by other welding methods: refractory metals (tungsten,
molybdenum, niobium) and chemically active metals (titanium, zirconium, beryllium). Electron Beam
Welding is also able to join dissimilar metals
Advantages of Electron Beam Welding (EBW):
•Tight continuous weld;
•Low distortion;
•Narrow weld and narrow heat affected zone;
•Filler metal is not required.
Disadvantages of Electron Beam Welding (EBW):
•Expensive equipment;
•High production expenses;
•X-ray irradiation
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45. Laser Beam Welding
Uses a laser beam to melt the metals; can be used for deep, narrow welds
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46. Laser Beam Welding
Laser welding of a pipe
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47. Advantages of Laser Welding:
Easily automated process;
Controllable process parameters;
Very narrow weld may be obtained;
High quality of the weld structure;
Very small heat affected zone; Dissimilar materials may be welded;
Very small delicate work pieces may be welded;
Vacuum is not required;
Low distortion of work piece.
Disadvantages of Laser Welding:
Low welding speed;
High cost equipment;
Weld depth is limited.
Laser Welding is used in electronics, communication and aerospace
industry, for manufacture of medical and scientific instruments, for
joining miniature components.
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48. THANK YOU
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