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Welding FundamentalUltrasonic WeldingUltrasonic Testing
Eng.Haitham Shehata Hussein
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Introduction Welding Fundamental
Welding Definition Weld Type Weld Shapes Weld Applications Weld Defects Welding Inspection
Ultrasonic Welding Ultrasonic Testing
Index
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Before we talk about
Ultrasonic Welding
we should present some info
about:
Welding fundamentals.
(Definition, Types, Shapes, Applications, Test and
inspection,...)
Introduction
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oWeld DefinitionIn its broadest context, welding is a process in
which materials of the same fundamental type or class are brought together and caused to join (and become one) through the formation of primary (and, occasionally, secondary) chemical bonds under the combined action of heat and pressure (Messler, 1993).
Welding Fundamental
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Electron Beam.
Brazing .
Soldering .
Electric Resistance .
Friction Stir .
Fusion Bonding .
Ultrasonic .
Manual Metal .
Tungsten Inert Gas .
Submerged Arc .
Gas Metal Arc .
Metal Inert Gas
Resistance Spot .
Flux-Cored Arc .
Laser Beam .
oWeld Types
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Iron and steel, stainless steel, aluminum, nickel, copper alloys
Materials
Steel structures, industrial fabrication Applications
Fabrication shop, factoryField operationsSuitable for indoor or outdoor use
Typical Location
Low equipment costs and wide applicabilityDominant process in repair and maintenanceBasically no thickness limitationsCan be used in almost any position
Advantages
Applications are limited by welder skillPotential safety issues if not monitoredApplications may require preheat
Limitations
Porosity, lack of fusion, incomplete penetration,and cracks
Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Manual Metal Arc - MMAShielded Metal Arc - SMA
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Stainless steel, non-ferrous materials, aluminum, magnesium
Materials
Aerospace and space vehicles, nuclearapplications, thin wall materials manufacturingapplications
Applications
Fabrication shop, factory Typical Location
Stronger, higher quality weldsUsed with thin materialsGreater operator control over the weldHighly resistant to corrosion and cracking
Advantages
Cannot be used on lead or zincEconomically not feasible for steelSlower production and difficult to master
Limitations
Porosity, lack of fusion, tungsten inclusions. Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Tungsten Inert GasTIG
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Carbon steel, stainless steel, nickel-basedalloys, low alloy steel, surfacing applications(i.e. weld buildup)
Materials
Structural and vessel construction, pipes Applications
Fabrication shop, factorySuitable for indoor or outdoor use
Typical Location
High deposition rates – deep weld penetrationLittle edge preparation is neededSingle pass welds can be made with thick platesArc is always covered under a blanket of fluxProduces sound, uniform, and ductile welds
Advantages
Limited to ferrous and some nickel based alloysLimited positions and requires flux handlingLimited to long straight seams or rotated pipesRequires inter-pass and post weld slag removal
Limitations
Porosity, inclusions, incomplete penetration,and lack of fusion.
Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Submerged ArcSAW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Sheet metal, aluminum alloys Materials
Automotive, weld studs and nuts to metal,weld screw machine parts to metal,join cross wires and bars
Applications
Fabrication shop, factory Typical Location
Limits the areas of excessive heatingEnergy controlled - more reliable weldsAllows closer spacing of weldsA production process can be completely automated
Advantages
Tends to harden the materialReduce fatigue strengthStretch or anneal the materialCause the material to warp
Limitations
Cracks, porosity and expulsion Typical DiscontinuitiesTypes
VT, UT Non-destructive Testing Methods
Resistance SpotRSW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Structural steel - aluminum sections – stainlesssteel and nickel alloys - some offshoreapplications
Materials
automotive, structural, ornamental Applications
Fabrication shop, factory - field applications Typical Location
Versatility and speedAdaptive to robotic automation
Advantages
Limited to indoor useUnusable underwaterWeld quality can fluctuate
Limitations
Dross and porosity, lack of fusion, excessivepenetration, silica inclusions, cracking, undercut
Typical DiscontinuitiesTypes
RT, UT Non-destructive Testing Methods
Gas Metal Arc – GMAWMetal Inert Gas – MIG
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Mild- and low-alloy steels, stainless steels,some high nickel alloys
Materials
Automotive, structural steels Applications
Factory - field applications Typical Location
No shielding gas is required making it suitable for outdoor welding and/or windy conditionsHigh-deposition rate processLess precleaning of metal requiredThe weld metal is protected initially from external factors until the flux is removed
Advantages
When the electrode contacts the base metal, the contact tip can melt fusing it to the base metalIrregular wire feed – usually the result of a mechanical problemMore costly filler material/wire than GMAW
Limitations
Porosity, lack of fusion, inclusions, incompletepenetration, hollow bead and cracks. Also,overlap, weld spatter, underfill, and undercut.
Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Flux-Cored ArcFCAW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Carbon steel, stainless steel, aluminum,titanium
Materials
Automotive, aerospace Applications
Factory Typical Location
Versatile process - high quality yieldUsed in high volume applicationsEasily automated with robotics
Advantages
Cracking with hi-carbon steelsSpeed depends on type and thickness of materials
Limitations
Porosity, cracks, lack of fusionAlso, “humping” and undercut
Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Laser BeamLBW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Stainless steel, super alloys, refractory metals
Materials
Automotive, aerospace, semiconductor Applications
Manufacturing facility Typical Location
Has a very small heat affected zoneIs used for dissimilar metal welds
Advantages
Lack of penetration, lack of fusion, cracking Limitations
Incomplete penetration, lack of fusion, cracksand porosity
Typical DiscontinuitiesTypes
VT, PT, MT, RT, UT Non-destructive Testing Methods
Electron BeamEBW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Copper, brass, bronze, aluminum and others
Materials
Electrical, electronics, transportation,appliances, and construction
Applications
Manufacturing / field - indoors or outdoors Typical Location
Easy to learn, virtually any dissimilar metal can be joined, the bond line can be very neat in appearance, and the joint strength is strong enough for most non-heavy-duty use applications.
Advantages
A badly brazed joint can look similar to a good joint, and can have a very low strength. The metal used to bond the two parts may be different in color than the parts being bonded.Long-term effects of dissimilar metals in constant contact may need to be examined for special applications. Since the filler material (typically bronze) melts at a relatively low temperature,brazed parts should not be put in an environmentwhich exceeds the melting point of the filler metal
Limitations
Lack of fill (unbond), porosity, cracks, and coldbond
Typical DiscontinuitiesTypes
VT, PT, UT Non-destructive Testing Methods
Brazing
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Copper, silver, gold, iron, nickel Materials
Electronic components, pipe soldering,aluminum, stained glass
Applications
Manufacturing / field - indoors or outdoors Typical Location
Soldering can be manual or automatedFormulated for maximum electrical conductivity
Advantages
Soldering difficulty can increase when other materials are involved
Limitations
Cold solder joint, oxidation, cracks and voids Typical DiscontinuitiesTypes
VT Non-destructive Testing Methods
Soldering
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Steel Materials
Round / square tubing Applications
Manufacturing Typical Location
High production - easy automationEnergy efficientTypically stronger than the material itselfVery durable weld
Advantages
Power source and material thickness must match
Limitations
Pin holes, cracks Typical DiscontinuitiesTypes
VT,PT, RT Non-destructive Testing Methods
Electric ResistanceERW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Aluminum - copper Materials
Ship building and offshore - aerospace andautomotive - railway rolling stock - specializedfabrication
Applications
Fabrication shop, factory Typical Location
Can be used on large pieces not post weld heat treatedUsed where metal characteristics must remain unchangedLow concentration of discontinuitiesCan operate in all positionsMinimum safety issues / low environment impact
Advantages
Exit hole left when tool is withdrawnHeavy duty clamping necessaryLess flexible and often slower
Limitations
Cracks and lack of penetration, kissing bonds Typical DiscontinuitiesTypes
UT, PT Non-destructive Testing Methods
Friction StirFSW
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Composites, stainless steels, alloys, ceramics
Materials
Aerospace Applications
Manufacturing Typical Location
Creates a bond by atomic attractionUsed with MEMS fabrication / silicon
Advantages
Must be highly polished, clean surfacesLow strength improved by thermal treatment
Limitations
Laminations, lack of bonding Typical DiscontinuitiesTypes
UT Non-destructive Testing Methods
Fusion Bonding
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
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Composites, plastics, dissimilar materials Materials
Aerospace, automotive, medical, computer,packaging
Applications
Manufacturing Typical Location
No other materials required in the processAlternative to glue, screws or snap fitEasily automatedClean, precise jointsUsed for electrical wire harness connections
Advantages
Only used for small weldsMajor limitation is material thicknessLimited by the amount of power available
Limitations
Determine the presence of unbonds Typical DiscontinuitiesTypes
VT Non-destructive Testing Methods
Ultrasonic
Visual Testing...............................VT *Penetrant Testing.......................PT*Magnetic Particle Testing.......MT*Radiographic Testing................RT**Ultrasonic Testing.......................UT**Eddy Current Testing.................ET***
* For surface discontinuities** For subsurface discontinuities*** For surface-breakingdiscontinuities and usuallyused to supplement PT, MT
The main topic that will be discussing it later
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Weld shapes or ( weld joints ) meaning the position of two parts that can be found when we weld it together .
There is five main types for joints that allow us to get the all requirement engineering shapes.
1- Butt. 2- Lap. 3- Corner.4- Edge. 3- T-joint.
oWeld Shapes
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Weld Shapes
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Application Solutions: Oil & Gas. Power Generation. Aerospace. Automotive. Rail. Ship Building
oWeld Application
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Oil & Gas
Power Generation
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Aerospace
Automotive
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Rail
Ship Building
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Welding defect :is any flaw that compromises the usefulness
of a weldment.According to the American Society of
Mechanical Engineers (ASME), welding defect causes are broken down as follows: 45 percent poor process conditions, 32 percent operator error, 12 percent wrong technique, 10 percent incorrect consumables, and 5 percent bad weld grooves.
Welding defect
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Major causes:Hydrogen embrittlement
is the process by which various metals, most importantly high-strength steel, become brittle and fracture following exposure to hydrogen.
Residual stressesAre stresses that remain after the original cause of the stresses (external forces, heat
gradient) has been removed.Heat from welding may cause localized expansion, which is taken up during welding
by either the molten metal or the placement of parts being welded. When the finished weldment cools, some areas cool and contract more than others, leaving residual stresses.
Welding defect
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Types of Defect:The following figures give a rough survey about
the classification of welding defects to DIN 8524. This standard does not classify existing welding defects according to their origin but only to their appearance.
Welding defect
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1- Defect Class: Shape DefectsWelding defect
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Welding defect
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2- Defect Class: Cracks and Cavities
Welding defect
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Welding defect
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Welding defect
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3- Defect Class: Lack of Fusion, Insufficient Through-Weld
Welding defect
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Welding defect
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4- Defect Class: Solid InclusionsWelding defect
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Welding defect
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Inspecting welds can reduce costs by detecting
discontinuities in the early stages of manufacturing,
reducing the cost of rework and extending the life of
components by detecting and correcting flaws. NDT
methods can identify cracking, porosity, incomplete
penetration, misalignment, inclusions, lack of fusion and
similar conditions, which can compromise weld strength.
oWeld Inspection
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Asset Life-Cycle Weld Inspection with Multi-Inspection Solutions:
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Ultrasonic WeldingWhat is Ultrasonic Welding?Ultrasonic plastic welding is the joining or reforming of
thermoplastics through the use of heat generated from high-frequency mechanical motion. It is accomplished by converting high-frequency electrical energy into high-frequency mechanical motion. That mechanical motion, along with applied force, creates frictional heat at the plastic components' mating surfaces (joint area) so the plastic material will melt and form a molecular bond between the parts.
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In 1960 Sonobond Ultrasonics, originally known as Aerospace projects, Incorporated, developed the first metal ultrasonic welding machine to be awarded a United States Patent.
Practical application of ultrasonic welding for rigid plastics was completed in the 1960s. At this point only hard plastics could be welded.
The first application of this new technology was in the toy industry.
Ultrasonic Welding History
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The first car made entirely out of plastic was assembled using ultrasonic welding in 1969. The automotive industry has used it regularly since the 1980s.
Ultrasonic welding can be used now for both hard and soft plastics, such as semicrystalline plastics, and metals.
Ultrasonic welding machines also have much more power now. The understanding of ultrasonic welding has increased with research and testing.
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Ultrasonic welding equipment consists of :
1.a machine press.2.Generator.3.converter or transducer.4.Booster.5.sonotrode or horn.6.component support tooling. A schematic of an ultrasonic
welding machine is shown in Fig.1.Fig.1. Schematic of ultrasonic welding machine
Ultrasonic Welding Equipments.
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Ultrasonic Welding Schematic .
Ultrasonic Welding Equipments.
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1-GeneratorThe generator converts electrical
power from the single-phase mains to the correct frequency and voltage for the transducer to convert into mechanical vibrations. The microprocessor unit controls the welding cycle and feeds back key welding information to the user, via the user interface. The user interface also allows the operator to enter the required welding parameters.
Ultrasonic Welding Equipments.
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2-Machine pressThe machine stand is designed
to hold the welding system or stack and apply the force necessary for welding. It consists of a base-plate, to hold the tooling jig, and a pneumatic cylinder to apply the force.
Ultrasonic Welding Equipments.
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3-Welding stackThis is the part of the machine
that provides the ultrasonic mechanical vibrations. It is generally a three-part unit consisting of transducer, booster and welding horn, mounted on the welding press at the centre-point of the booster section. The stack is a tuned resonator, rather like a musical instrument tuning fork. In order to function, the resonant frequency of the tuned welding stack must closely match the frequency of the electrical signal from the generator (to within 30Hz).
Ultrasonic Welding Equipments.
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4-TransducerThe transducer, also known as the
converter, converts the electrical energy from the generator to the mechanical vibrations used for the welding process. Between each of the discs there is a thin metal plate, which forms the electrode. As the sinusoidal electrical signal is fed to the transducer via the electrodes, the discs expand and contract, producing an axial, peak-to-peak movement of 15 to 20µm.Transducers are delicate devices and should be handled with care. Once the elements are broken, the transducer will not function.
Ultrasonic Welding Equipments.
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5-BoosterThe booster section of the welding stack
serves two purposes, primarily to amplify the mechanical
vibrations produced at the tip of the transducer and transfer them to the welding horn. Its
secondary purpose is to provide a location for mounting the stack on the welding press.
The booster expands and contracts as the transducer applies the ultrasonic energy.
Ultrasonic Welding Equipments.
Fig.2. Ultrasonic welding boosters
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6-Welding horn
The welding horn is the element of the welding stack that supplies energy to the component being welded. A typical welding horn is shown in Fig.3. Design of the welding horn is critical to successful welding. It is strongly recommended that welding horn manufacture should only be carried out by companies specializing in ultrasonic welding.
Ultrasonic Welding Equipments.
Fig.3. Ultrasonic welding Horn
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Ultrasonic Welding Equipments.7-Support tooling
Finally, the base of the machine press supports the tooling that supports the components during the welding operation. The support tooling is designed to prevent movement of the lower component while the ultrasound is applied. It is often machined to match the contours of the component surface intimately.
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The basic principle of ultrasonic welding
The two thermoplastic parts to be assembled are placed together, one on top of the other, in a supportive nest called a fixture.
Step 1 - Parts in fixture
A titanium or aluminum component called a horn is brought into contact with the upper plastic part.
Step 2 - Horn contact
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The basic principle of ultrasonic welding
A controlled pressure is applied to the parts, clamping them together against the fixture.
Step 3 - Pressure applied
The horn is vibrated vertically 20,000 (20 kHz) or 40,000 (40 kHz) times per second, at distances measured in thousandths of an inch (microns), for a predetermined amount of time called weld time. Through careful part design, this vibratory mechanical energy is directed to limited points of contact between the two parts . >>
Step 4 - Weld time
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The mechanical vibrations are transmitted through the thermoplastic materials to the joint interface to create frictional heat. When the temperature at the joint interface reaches the melting point, plastic melts and flows, and the vibration is stopped. This allows the melted plastic to begin cooling.
The clamping force is maintained for a predetermined amount of time to allow the parts to fuse as the melted plastic cools and solidifies. This is known as hold time. (Note: Improved joint strength and hermeticity may be achieved by applying a higher force during the hold time. This is accomplished using dual pressure.)
Step 5- Hold time
The basic principle of ultrasonic welding
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The basic principle of ultrasonic welding
Once the melted plastic has solidified, the clamping force is removed and the horn is retracted. The two plastic parts are now joined as if molded together and are removed from the fixture as one part.
Step 6- Horn retracts
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The benefits of ultrasonic welding : Much faster than conventional adhesives or solvents. The drying time is very quick. The pieces do not need to remain in a jig for long periods
of time waiting for the joint to dry or cure. The welding can easily be automated, making clean and
precise joints. The site of the weld is very clean and rarely requires any
touch-up work. The low thermal impact on the materials involved enables
a greater number of materials to be welded together.
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Ultrasonic Welding ApplicationsThe applications of ultrasonic welding are extensive and are found in many industries including 1- electrical and computer, 2- automotive and aerospace,3- medical, and packaging. Whether two items can be ultrasonically welded is determined by their thickness.
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Ultrasonic Welding SafetyUltrasonic welding machines, like most industrial equipment, pose the risk of some hazards. These include :1. exposure to high heat levels and voltages.2. This equipment should always be operated using the safety
guidelines provided by the manufacturer in order to avoid injury. 3. For instance, operators must never place hands or arms near the
welding tip when the machine is activated. 4. operators should be provided with hearing protection and safety
glasses.5. Operators should be informed of the OSHA regulations for the
ultrasonic welding equipment and these regulations should be enforced.
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Definition In ultrasonic testing (UT), very short ultrasonic pulse-waves with center
frequencies ranging from 0.1-15 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to characterize materials. A common example is ultrasonic thickness measurement, which tests the thickness of the test object, for example, to monitor pipework corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is a form of non-destructive testing used in many industries including aerospace, automotive and other transportation sectors.
Ultrasonic Testing
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How It WorkIn ultrasonic testing, an ultrasound transducer connected to a diagnostic machine is passed over the object being inspected. The transducer is typically separated from the test object by a couplant (such as oil) or by water, as in immersion testing. However, when ultrasonic testing is conducted with an Electromagnetic Acoustic Transducer (EMAT) the use of couplant is not required.
Ultrasonic Testing
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Principle of ultrasonic testing. A probe sends a sound wave into a test material. There are two indications, one from the initial pulse of the probe, and the second due to the back wall echo. RIGHT: A defect creates a third indication and simultaneously reduces the amplitude of the back wall indication. The depth of the defect is determined by the ratio D/Ep
Ultrasonic Testing
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Example:At a construction site, a technician tests a pipeline weld for defects using an ultrasonic phased array instrument. The scanner, which consists of a frame with magnetic wheels, holds the probe in contact with the pipe by a spring. The wet area is the ultrasonic couplant that allows the sound to pass into the pipe wall.
Ultrasonic Testing
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Any Question?
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