Ultrasonic weld test

Before we talk about
we should present some
info about:
(Definition, Types, Shapes,
Applications, Test and
inspection,...)

In 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).

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 .

Iron and steel, stainless steel, aluminum, nickel,
copper alloys
Materials
Steel structures, industrial fabricationApplications
Fabrication shop, factory
Field operations
Suitable for indoor or outdoor use
Typical Location
Low equipment costs and wide applicability
Dominant process in repair and maintenance
Basically no thickness limitations
Can be used in almost any position
Advantages
Applications are limited by welder skill
Potential safety issues if not monitored
Applications may require preheat
Limitations
Porosity, lack of fusion, incomplete penetration,
and cracks
Typical Discontinuities
Types
VT, PT, MT, RT, UTNon-destructive
Testing Methods
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-breaking
discontinuities and usually
used to supplement PT, MT

Stainless steel, non-ferrous
materials, aluminum, magnesium
Materials
Aerospace and space vehicles, nuclear
applications, thin wall materials manufacturing
applications
Applications
Fabrication shop, factoryTypical Location
Stronger, higher quality welds
Used with thin materials
Greater operator control over the weld
Highly resistant to corrosion and cracking
Advantages
Cannot be used on lead or zinc
Economically not feasible for steel
Slower production and difficult to master
Limitations
Porosity, lack of fusion, tungsten inclusions.Typical Discontinuities
Types
Testing Methods

Carbon steel, stainless steel, nickel-based
alloys, low alloy steel, surfacing applications
(i.e. weld buildup)
Materials
Structural and vessel construction, pipesApplications
Fabrication shop, factory
Suitable for indoor or outdoor use
Typical Location
High deposition rates – deep weld penetration
Little edge preparation is needed
Single pass welds can be made with thick plates
Arc is always covered under a blanket of flux
Produces sound, uniform, and ductile welds
Advantages
Limited to ferrous and some nickel based alloys
Limited positions and requires flux handling
Limited to long straight seams or rotated pipes
Requires inter-pass and post weld slag removal
Limitations
Porosity, inclusions, incomplete penetration,
and lack of fusion.
Types
Testing Methods

Sheet metal, aluminum alloysMaterials
Automotive, weld studs and nuts to metal,
weld screw machine parts to metal,
join cross wires and bars
Applications
Limits the areas of excessive heating
Energy controlled - more reliable welds
Allows closer spacing of welds
A production process can be completely
automated
Advantages
Tends to harden the material
Reduce fatigue strength
Stretch or anneal the material
Cause the material to warp
Limitations
Cracks, porosity and expulsionTypical Discontinuities
Types
VT, UTNon-destructive
Testing Methods

Structural steel - aluminum sections – stainless
steel and nickel alloys - some offshore
applications
Materials
automotive, structural, ornamentalApplications
Fabrication shop, factory - field applicationsTypical Location
Versatility and speed
Adaptive to robotic automation
Advantages
Limited to indoor use
Unusable underwater
Weld quality can fluctuate
Limitations
Dross and porosity, lack of fusion, excessive
penetration, silica inclusions, cracking, undercut
Types
RT, UTNon-destructive
Testing Methods

Mild- and low-alloy steels, stainless steels,
some high nickel alloys
Materials
Automotive, structural steelsApplications
Factory - field applicationsTypical Location
No shielding gas is required making it suitable
for outdoor welding and/or windy conditions
High-deposition rate process
Less precleaning of metal required
The 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 metal
Irregular wire feed – usually the result of a
mechanical problem
More costly filler material/wire than GMAW
Limitations
Porosity, lack of fusion, inclusions, incomplete
penetration, hollow bead and cracks. Also,
overlap, weld spatter, underfill, and undercut.
Types
Testing Methods

Carbon steel, stainless steel, aluminum,
titanium
Materials
Automotive, aerospaceApplications
FactoryTypical Location
Versatile process - high quality yield
Used in high volume applications
Easily automated with robotics
Advantages
Cracking with hi-carbon steels
Speed depends on type and thickness of
materials
Limitations
Porosity, cracks, lack of fusion
Also, “humping” and undercut
Types
Testing Methods

Stainless steel, super alloys, refractory metalsMaterials
Automotive, aerospace, semiconductorApplications
Manufacturing facilityTypical Location
Has a very small heat affected zone
Is used for dissimilar metal welds
Advantages
Lack of penetration, lack of fusion, crackingLimitations
Incomplete penetration, lack of fusion, cracks
and porosity
Types
Testing Methods

Copper, brass, bronze, aluminum and othersMaterials
Electrical, electronics, transportation,
appliances, and construction
Applications
Manufacturing / field - indoors or outdoorsTypical 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 environment
which exceeds the melting point of the filler metal
Limitations
Lack of fill (unbond), porosity, cracks, and cold
bond
Types
VT, PT, UTNon-destructive
Testing Methods

Copper, silver, gold, iron, nickelMaterials
Electronic components, pipe soldering,
aluminum, stained glass
Applications
Manufacturing / field - indoors or outdoorsTypical Location
Soldering can be manual or automated
Formulated for maximum electrical conductivity
Advantages
Soldering difficulty can increase when other
materials are involved
Limitations
Cold solder joint, oxidation, cracks and voidsTypical Discontinuities
Types
VTNon-destructive
Testing Methods

SteelMaterials
Round / square tubingApplications
ManufacturingTypical Location
High production - easy automation
Energy efficient
Typically stronger than the material itself
Very durable weld
Advantages
Power source and material thickness must matchLimitations
Pin holes, cracksTypical Discontinuities
Types
VT,PT, RTNon-destructive
Testing Methods

Aluminum - copperMaterials
Ship building and offshore - aerospace and
automotive - railway rolling stock - specialized
fabrication
Applications
Can be used on large pieces not post weld heat
treated
Used where metal characteristics must remain
unchanged
Low concentration of discontinuities
Can operate in all positions
Minimum safety issues / low environment
impact
Advantages
Exit hole left when tool is withdrawn
Heavy duty clamping necessary
Less flexible and often slower
Limitations
Cracks and lack of penetration, kissing bondsTypical Discontinuities
Types
UT, PTNon-destructive
Testing Methods

Composites, stainless steels, alloys, ceramicsMaterials
AerospaceApplications
Creates a bond by atomic attraction
Used with MEMS fabrication / silicon
Advantages
Must be highly polished, clean surfaces
Low strength improved by thermal treatment
Limitations
Laminations, lack of bondingTypical Discontinuities
Types
UTNon-destructive
Testing Methods

Composites, plastics, dissimilar materialsMaterials
Aerospace, automotive, medical, computer,
packaging
Applications
No other materials required in the process
Alternative to glue, screws or snap fit
Easily automated
Clean, precise joints
Used for electrical wire harness connections
Advantages
Only used for small welds
Major limitation is material thickness
Limited by the amount of power available
Limitations
Determine the presence of unbondsTypical Discontinuities
Types
VTNon-destructive
Testing Methods
The main topic that will be discussing
it later

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.

Application Solutions:
 Oil & Gas.
 Power Generation.
 Aerospace.
 Automotive.
 Rail.
 Ship Building

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.

Hydrogen embrittlement
is the process by which various metals, most importantly high-strength steel,
become brittle and fracture following exposure to hydrogen.
Residual stresses
Are 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.

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.

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.

Asset Life-Cycle Weld Inspection with Multi-Inspection
Solutions:

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.

 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.

 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.

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

1-Generator
The 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.

2-Machine press
The 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.

3-Welding stack
This 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).

4-Transducer
The 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.

5-Booster
The 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.
Fig.2. Ultrasonic welding boosters

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.
Fig.3. Ultrasonic welding Horn

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.

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

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

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

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

 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.

The 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.

Ultrasonic 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.

 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.

In 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.

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

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 weld test

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