Ultrasonic is a rate of high frequency method, which is too much high that the note produced lies beyond the range of human hearing. The vibration is the source of energy or frequency.
Ultrasonic welding is categorized in a solid state of welding process where joint is produced by the local application of high frequency to the work pieces which are held together under pressure. The average frequency is used in ultrasonic welding is about 20 kHz and lower cases 10 kHz, but in some special circumstances is used high frequency as 170 kHz.
It is a molecular movement process by which the combination of pressure and high vibration. The metallic bonding is carried out in solid state, without applying of heat, filler rod or high pressure.
Principle operation of ultrasonic welding
First only degreasing should require from weld surfaces because, it can not be removed by this welding process. Otherwise the insulation coating, moisture, oxides are split up and removed very easily by ultrasonic high frequency.
Which work pieces to be weld that should be well clamped between the sonotrode tip and anvil. The contacting face of weld tip and anvil is made of HSS or High Speed Steel because of here wear can occur during welding (HSS is the wear resistant metal). The sonotrode and anvil in which surfaces to be contacted with work piece, that should be well surface finish. It is usual to have a slightly radius surface on the sonotrode tip face, the ratio is about 50 to 100 times the thickness of the weld material.
A frequency converter is employed, which is converted the line frequency 50Hz into high frequency electrical power. A transducer attachment converts the electrical frequency into ultrasonic high frequency energy. The high frequency energy transmitted to the weld joint through the welding tip. A coupler is made the bridge between welding tip and transducer. The tip oscillates on the weld joint with the help of some mechanism.
Dynamic shear stresses are generated in-
Principle diagram of ultrasonic welding
Advantages of ultrasonic welding-
Applications of ultrasonic welding-