The document discusses the principles and components of ultrasonic welding. It begins by explaining that ultrasonic welding works by using ultrasonic wave energy to create dynamic shear stress between workpieces, causing local plastic deformation and heat generation through friction, which forms a joint at the interface. It then lists the important components of an ultrasonic welding system, including the converter, booster, horn, fixture, and power supply. It describes different types of ultrasonic welding mechanisms and processes. It discusses applications of ultrasonic welding in various industries such as automotive, packaging, hygiene, medical, electronics, and consumer goods. Finally, it explains that plastic and metal can be joined using ultrasonic welding by using energy directors made of the plastic material

1. Q1. Explain the principle of ultrasonic welding process?
It works on the basic principle of energy of ultrasonic wave. Ultrasonic vibration creates a
dynamic shear stress between the contacts of two work piece. Due to local plastic
deformation and heat generate due to friction between contact surfaces, joint formation will
take place at the interface.
Q2. List the important components of ultrasonic welding technique? List the variations in
ultrasonic welding mechanisms? List the types of ultrasonic welding processes?
Booster: The booster amplifies the magnitude of the mechanical vibrations from the
converter and delivers the vibration to the horn.
Converter: Made up of piezoelectric ceramic discs, the converter takes electrical energy and
converts it into mechanical vibrations.
Fixture (or nest): Supports the plastic parts during the weld.
Gain: The amount by which amplitude is increased or decreased in a booster or horn.
Measured as the ratio of output amplitude to input amplitude.
Horn: The horn transmits the ultrasonic vibrations to the plastic parts themselves. The horn
often is custom-tailored for a specific part and is one of the most crucial elements of an
ultrasonic welding system.
Power Supply: Converts incoming line power into an ultrasonic signal.
Trigger Force: The minimum force that must be applied to the parts prior to ultrasonic
energy being applied.
Ultrasonic Stack: The mechanical structure consisting of the converter, booster and horn in
the ultrasonic welder.
Variation in Ultrasonic Welding:
1. Ultrasonic Welding – Plastic (Vertical Amplitude type)
2. Ultrasonic Welding – Metal (Horizontal Amplitude type)
3. Ultrasonic Torsional Weld
Type of Ultrasonic Welding:
1. Ultrasonic Seam Welding
2. Ultrasonic Spot Welding
3. Ultrasonic Ring Welding
Q3. List the applications of Ultrasonic Welding Process in different fields?
Automotive industry applications:
 High-strength and fast
 Dimensionally accurate

2. Packaging industry applications:
Ultrasonic sealing technology has become an established and economic alternative of heat
sealing.
Hygiene industry applications:
Materials are joined by means of locally limited heat generation
 Skin-friendly
 Fast
Medical industry applications:
Ultrasonic welding ensures maintained functionality of the components and provides
continuous process monitoring unrivaled by other processes.
Electronic industry applications:
Ultrasonic welding is particularly suitable for their production and complies with product
requirements.
Consumer industry applications:
Using ultrasonic, consumer components can be produced and joined in a cost-effective way;
at the same time, the process provides great flexibility in terms of design. High
requirements for visual appearance, production speed, or geometry are met.
Q4. Explain how would you join a plastic with a metal using ultrasonic welding process?
A common practice in USPW of thermoplastic polymers and composites is the use of so-called
energy directors (EDs). These can be either some shaped protuberance or flat films at the
interface between the two joining partners. They consist only of neat polymeric material
which experiences larger strain than the bulk material because of the lower stiffness leading
to preferential melting at the interface. The polymer at the interface is brought to a viscous
state by applying heat, and, subsequently, the two surfaces are brought into intimate contact,
followed by cooling under pressure for consolidation. Direct adhesion between the metal
surface and the thermoplastic matrix occurs in this type of joints. Mechanical interlocking and
adsorption are therefore believed to have the biggest influence on joint strength.