Ultrasonic Spot Welding Equipment WW2803L

The role of the power supply is to convert the incoming line voltage (at 50 or 60Hz) into a new frequency. This electrical energy then is sent to the converter, which as the name implies, converts the electrical energy into mechanical vibrations. The converter consists of piezoelectric ceramic discs, which expand and contract at the rate of the supplied electrical energy. The magnitude of the vibrations is referred to as amplitude, a term that becomes very important when specifying an ultrasonic system for a given application. The vibrations then are transmitted through the booster, which typically increases the amplitude by a predetermined multiple, also known as gain. Finally, the booster’s output amplitude is transmitted through the horn, where it then can be delivered to the plastic parts.

Ultrasonic welding machine composition

An ultrasonic generator (power supply)

An ultrasonic converter (transducer)

An ultrasonic booster

An ultrasonic welding tool (horn/sonotrode)

Longer service life

Transducer prestress

All piezoelectric transducers for ultrasonic welding are of the Langevin type — i.e., one or more piezoceramics that are mechanically compressed (prestressed) between a front driver and a back
driver.

Because piezoceramics are weak in tension, a static compressive prestress must be applied to prevent the piezoceramics from ever experiencing tensile stresses when the transducer vibrates ultrasonically. In addition, the prestress assures that the piezoceramic interfaces make good contact so that the acoustic waves transmitt well with minimum loss. We use the most convenient center screw design.

A specific prestress can be obtained by tightening the transducer center screw to tighten the transducer. The traditional method is to use a torque wrench for tightening, but this parameter is
affected by many factors and often has deviations.

When the tightening of the ultrasonic transducer is insufficient, its impedance is large, which will cause serious heat generation; when the tightening is excessive, it is easy to cause problems such as damage to the ceramic sheet (crystal crack) and durability. Transducer is the most important part of ultrasonic welding equipment. So it is very important to accurately tighten the transducer and obtain the best prestress.

Piezoelectric ceramic sheet

Piezoceramics are typically classified as “soft” or “hard”. Hard piezoceramics are used for power applications. Among hard piezoceramics there are two basic types, generally designated as PZT4 and PZT8 (PZT stands for lead-zirconate-titanate of which the piezoceramics are composed). Different manufacturers may have their own designations for these types but the general performance is similar. Our device uses PZT8 piezoelectric ceramics, which has better relative performance.

Advantages of ultrasonic spot welding

Ultrasonic welding has many advantages when compared to traditional welding technologies. Many industries use ultrasonic welding due to these specific combinations of merits.

Application of ultrasonic spot welding

Ultrasonic welding is an eco-friendly process that takes seconds, consumes very little energy and reduces costs while maintaining a high degree of quality. The equipment fuses contact points on cell phones and other consumer electronics that are generally inaccessible with other welding methods. These techniques can be adapted to a wide range of commercial and industrial applications. In the food industry, the ultrasonic welding process is used to create a hermetic seal. It can fasten blister packs and facilitate the manufacturing of a variety of products, including toys, disposable lighters , pipettes and intravenous catheters.

Ultrasonic welding is commonly used in the plastics, aerospace and automotive industries to join similar materials. It is particularly useful in the production of medical products. Since the process does not introduce exhaust or other contaminants and the welds do not degrade, the manufacturing equipment can be used in a clean-room environment.

Ultrasonic spot welding tips