Ultrasonic welding: Introduction ,types and definitions

ultrasonic welding

Ultrasonic welding  

The Ultrasonic welding process is a type of solid-state welding process wherein welding is done by the local application of high-frequency vibratory energy to workpieces, held together under pressure.

Introduction

Ultra Sonic Welding is a solid-state welding process. Its first use began around the 1960s with toy making. Ultrasonic welding is a solid-state welding process. Its first use began around the 1960s with toy making.
In fact, the workpieces are held together under a modest static force normal to their interfaces and oscillating shear stresses of the ultrasonic frequencies are applied parallel to the plane of the interface for about one second, but usually less than one second. The combined effect of pressure and vibration causes a sound association between the motion of metal molecules and the face of the material in contact. The relationship of the workpiece does not depend on the melting of their surfaces, nor does it involve high pressure and large deformation. Rather bonding is prepared in the solid-state, without external heat, filler rods, or high pressure.

Principle of Operation

ultrasonic welding

Since the vibrating action in ultrasonic welding causes the moisture, oxides, and other coatings to break or disperses normally, it only requires a cleaning process before welding. This is faster than conventional adhesives or solvents. Ultrasonic weld process takes 0.5 to 1.5 seconds only.

When the vibration rate is so high that the note produced is beyond the range of human hearing, the vibration ratio is called ultrasonic. The vibration rate used in the ultrasonic welding process is 20 khz to 70 khz.

Types of ultrasonic welding

The following types of ultrasonic welds are commonly used.

Spot weld, Seam weld, Ring weld, and Line weld

Equipment used in ultrasonic welding

Ultrasonic welding includes the following equipment:

Frequency Converter

The frequency converter is used to obtain high-frequency electric power at the design frequency of the welding system. Ultrasonic welding equipment can be operated by electron tube frequency converters, motor alternators, or silicon controlled rectifier converters.

Transducer-coupling system

The transducer is used to convert electrical energy into elastic vibrate power and a coupling system with sonotrode tip that organizes the vibratory energy to the weld zone.

Anvil

The anvil acts as a support for the workpiece and provides the necessary response to the clamping force.

Force application tools in ultrasonic welding

A variety of force application tools are commonly used for static loads on the plane of the weld surface. For smaller machines, Spring activated, it works pneumatically in medium-sized machines and is used hydraulically with larger units.

Timer

Timers are used to control weld intervals in spot type, ring and line welding, and a rotating and translating mechanism for continuous seam welding.

Conclusion

Ultrasonic welding is particularly suited for welding thin metal sections, using lap joints as electrical resistance welding and cold pressure welding.
Joining of electrical /electronic components. Hermetic sealing of volatile substances, Welding aluminum wire and sheet, metallic junctions and in producing a variety of joint configurations, Continuous seam welding has been used to assemble components of corrugated heat exchangers, The strainer screen is welded without clogging holes,
Spot welding using special tip and anvil is applied to pinch-off welds in copper and aluminum tubing used with capillary tubes in refrigeration in air conditioning.