ULTRASONIC WELDING
Electrical
Solid
State
Welding
Chemical
Friction
Mechanical
Pressure
Ultrosonic
Weld
Definition of Ultrasonic Welding
A solid state welding process in which
coalescence is produced at the faying
surfaces by the application of high
frequency vibratory energy while the
work pieces are held together under
moderately low static pressure.
Ultrasonic Welding Process
Clamping
force
Process
Description:
• Components of
Sonotrode
ultrasonic welding
tip
system include: Vibration
– Transducer
– Sonotrode
– Anvil
Mass
wedge Transducer
Weldment
Anvil
Force
Ultrasonic Welding Mechanism
Clamping
force
• A static clamping force is
applied perpendicular to the
interface between the work
pieces.
• The contacting sonotrode
oscillates parallel to the
interface. 10-75 KHz
• Combined effect of static and
oscillating force produces
deformation which promotes
welding.
Mass
wedge Transducer
Sonotrode
tip
workpiece
Anvil
Force
Process Variations
• Spot Welding
• Ring Welding
• Line Welding - Linear Sonotrode
• Continuous Seam Welding - Roller Sonotrode
• Microminiature Welding
Typical 1500 ultrasonic
spot-type welding machine
Courtesy AWS handbook
AWS Welding Handbook
100 W
Lateral Drive
Ultrasonic
Welder
AWS Welding Handbook
Typical Ring Welding Applications
Tip in Shape of Weld
AWS Welding Handbook
Attachment for Continuous Ring Welding
AWS Welding Handbook
Tip
Traversing Head for Continuous Seam Welding
AWS Welding Handbook
Welding Variables
Ultrasonic Welding Variables
•
•
•
•
•
Ultrasonic power
Clamping force
Welding time
Frequency
Linear Vibration Amplitude
Power Generation
Ultrasonic Welding Power
Generation
Frequency
converter
Electrical
energy
Transducer
• Electrical power of 60
Hz is supplied to the
frequency converter.
• The frequency
converter converts the
required 60 Hz signal
to the welding
frequency (from 10 to
75 kHz).
Vibratory
transducer
AWS Welding Handbook
Power Generation
Ultrasonic Welding Power
Generation
• Frequency is transformed to
vibration energy through the
transducer.
• Energy requirement
established through the
following empirical
relationship.
–
–
–
–
E = K (HT)3/2
E = electrical energy
H = Vickers hardness number
T = thickness of the sheet
Electrical
energy
Frequency
Converter
Vibratory
transducer
Power Requirements
E  K(HT)
3/2
Where:
E = electrical energy, W*s (J)
k = a constant for a given welding system
H = Vickers hardness number of the sheet
T = thickness of the sheet in contact with the sonotrode
tip, in. (mm)
The constant “K” is a complex function that appears to involve primarily
the electromechanical conversion efficiency of the transducer, the
impedance match into the weld, and other characteristics of the welding
system. Different types of transducer systems have substantially different
K values.
Source AWS handbook
AWS Welding Handbook
AWS Welding Handbook
Sonotrode Tip and Anvil Material
High Speed Tool Steels Used to Weld
• Soft Materials
• Aluminum
• Copper
• Iron
• Low Carbon Steel
Hardenable Nickel-Base Alloys Used to Weld
• Hard, High Strength Metals and Alloys
Ultrasonic Welding Interfacial
Interaction
• Localized temperature rises resulting from
interfacial slip and plastic deformation.
• Temperature is also influenced by power,
clamping force, and thermal properties of
the material.
• Localized Plastic Deformation
• Metallurgical phenomena such as
recrystallizing, phase transformation, etc.....
can occur.
Ultrasonic Welding Materials Combinations
Source AWS handbook
Extreme Interpenetration
Nickel Foil (top) to Gold-Plated Kovar Foil
Local Plastic Flow
Dark Regions are Trapped Oxide
Nickel Foil (top) to Molybdenum Sheet
Very Little Penetration, Thin
Bond Line, Fiber Flow
Molybdenum Sheet to Itself
AWS Welding Handbook
Comparison With Resistance Spot Weld
AWS Welding Handbook
Advantages of Ultrasonic
Welding
• No heat is applied and no melting occurs.
• Permits welding of thin to thick sections.
• Welding can be made through some surface
coatings.
• Pressures used are lower, welding times are
shorter, and the thickness of deformed
regions are thinner than for cold welding.
Limitations of Ultrasonic
Welding
• The thickness of the component adjacent to
the sonotrode tip must not exceed relatively
thin gages because of power limitations of
the equipment.
• Process is limited to lap joints.
• Butt welds can not be made because there is
no means of supporting the workpieces and
applying clamping force.
Other Process Variations
• Ultrasonic Welding of Non-metallic
• Ultrasonic Plastic Welding
Welds Can Be Made to Non-Metallic
Substrate Materials Coated with Thin
Layers of Metal Films
Material Welded
Metal Film
Non-Metallic
AWS Welding Handbook
Ultrasonic Welding of Plastics
• Advantages
– Fast
– Can spot or seam weld
• Limitations
– Equipment complex,
many variables
– Only use on small parts
– Cannot weld all plastics
0.1.1.2.5.T25.95.12
Applications of Ultrasonic
Welding
• Assembling of electronic components such
as diodes and semiconductors with
substrates.
• Electrical connections to current carrying
devices including motors, field coils, and
capacitors.
• Encapsulation and packaging.
• Plastic parts
AWS Welding Handbook
Note weld progression (no weld in center)
AWS Welding Handbook
Starter motor armature with wires
joined in commutator slots by
ultrasonic welding
Ultrasonically welded Helicopter
access door.
Courtesy AWS handbook
Field coil assembled by ultrasonic welding
Courtesy AWS handbook
AWS Welding Handbook
Wire Bundle Placed in Jaws
Ultrasonic
Tying Tool
Metal Tape Fed
Around bundle of
Wires and welded
once, then cut and
welded again.
Ultrasonic
Horn
Bundled Wires
Welds
First Weld Made
Cut and Second Weld Made
Ultrasonic Stitch (Clad) Welding
Sonatrode
Anvil
Louks, et al “Ultrasonic Bonding Method” US Patenet 6,099,670 Aug. 8, 2000
Ultrasonic Welding of Eraser Holder on Plastic Pencil
Coinon, A, Trajber, Z, “Pencil Having and Eraser-Holding
Ferrule Secured by Ultrasonic Welding” US Patent 5,774,931
July 7, 1998
Explosive Gas Generator For Auto Air Bag
(Plastic Ultrasonic Weld)
Gas Generating
Explosive Powder
Primer
Plastic Cap
Welded to
Plastic Base
Ultrasonic Weld
Avory, et al “Electrical Initiator” US Patent 5,763,814 June 9, 1998.