ULTRASONIC WELDING

Ultrasonic welding is a technology mainly used for pieces, made of thermoplastic material, which overworks the mechanical action exerted by the high frequency sound waves (ultrasound, precisely). The plastic components are put in contact with each other by applying a normal variable load and putting into vibration a part respect to the other by means of the vibrating group. The vibrating group is composed by the transducer and by the booster where, to the end of it, is screwed the sonotrode.
The sonotrode generates friction between the parties and this intense vibration, produces heat. Consequently the thermoplastic materials are melted ensuring the welding and the assembly.

The ultrasonic generator, transforms the low-frequency energy (50 Hz), elevating it to a higher frequency (20 kHz or more).
Sirius Electric manufactures systems with frequencies of 20 - 30 - 36 - 40 kHz. The transducer, also called converter or transmitter, converts the electrical impulses into a mechanical motion. The booster, or mechanical amplifier, transmits the mechanical vibration of the transducer to the sonotrode that is brought in contact with the work piece. The sonotrodes can be made in different materials, depending on the type of use, and follow the shape of the piece.

One of the most important features in the ultrasonic welding is definitely the geometry of the bonding surfaces. To obtain short welding cycles, it takes the welding joints also known conveyors of energy or energy directors.
Their configuration and size, is designed according to the type of welding to be performed and the material to be welded. If the welding joint is less than 6 mm from the contact’s sonotrode zone, we speak of near field welding while, if higher, far-field welding. The realization of the holding fixture, also called support or anvil, is managed internally and with the use of numerical control machines.

VIBRATION WELDING

Another technology that develops heat by friction, is the vibration welding. The local temperature increase, necessary for the melting process, is obtained by rubbing one of the two pieces to be welded.
On the piece subjected to movement, a thrust pressure is applied in order to keep in contact the parts to join together during the welding process. This technology is suitable for the welding of thermoplastic materials with complex shapes, or made of special materials and in some cases represents a viable alternative to the ultrasonic welding.

An electric motor, controlled by an appropriate drive, provides the main rotational motion. Through the programming keyboard, it is possible to set the frequency and consequently, the number of rpm. The rotation shaft is made with particular geometry and allows to transform the rotary motion, into vibratory motion.

The vibration welder manufactured by Sirius Electric is with circular movement and this movement is obtained by an electric motor and by the rotation of a shaft with the possibility to generate an eccentricity and so a vibratory motion. Even in this case, the dimension of the pieces, in particular in the assembly area, must be carefully evaluated. We study welding joints suitable for any specific need taking into consideration the mechanical seal, the welding quality and the aesthetic level of the welded parts.

This technology is part of our production machines for assembly of plastic parts. The production of vibration welders, takes place entirely in the Sirius Electric factory based in Vigevano. The sale of the vibration welders, is managed directly by our sales department. Even in this technology, as indeed for all other solutions, the sale must be conducted in close cooperation with the customer, trying to carefully study all the technological aspects related to thermoplastic materials and the geometry of the parts to be assembled with the circular vibration welding.

HOT PLATE WELDING

With the technology of hot-plate welding, the melting of thermoplastic materials occurs by direct contact with a plate, realized according to the shape of the pieces to be welded, heated and electronically thermo regulated with a temperature between 250 and 350 ° C. With modern electronic temperature control, you can check very precisely the temperature of heating.
This is one of the fundamental parameters featuring this technology. Another important parameter is the control of the pressure applied during the welding which can happen with pneumatic circuit or with the hydraulic circuit.

The two pieces to be assembled are contained in their workpiece supports and the cycle of hot plate welding is performed automatically, managed by setting the heating and cooling time.
Mechanical movements of the machine, must be fast so that the heating and melting of the welding joint, is sufficiently plastic for the interpenetration of the two parts to be welded. On the equipment, there are the mechanical locks which determine the fusion and packing quotes of the parts to be assembled. To ensure mechanical movements, fast and very reliable, it must build carriages movement with hardened bars and linear ball bearings. The sale of hot-plate welders, find a lot of space within the assembly of pieces made with semi-crystalline thermoplastic materials, such as polypropylene, with particular reference to household appliances and automotive field. Condition to be respected almost always, is the tightness of the welded parts. The aesthetics are always to be taken into consideration and for this reason we study specific welding joints.

The production of hot-plate welders by Sirius Electric, includes two models of machines: hot plate welder model Basic and hot plate welder model Linear. The Basic stands out for its ease of use and its quality / price ratio. It is unique in its kind as it is a bench-type welder. The Linear is suitable for hot plate welding of pieces with medium to large dimensions. This machine can be equipped with an hydraulic power unit to have a thrust pressure between the two parts that is especially high. It is possible the manufacture of special welding machines, suitable to satisfy specific industrial needs.

FRICTION WELDING or SPIN WELDING

The welding of plastics, which employs the friction welding technology, is carried out by the melting of the contact surfaces. In the spin welding, as the name implies, the heat required for the welding is produced by the movement generated by a rotating spindle, combined with a boost pressure. For this reason, the process is suitable only for circular pieces.

The parts to be assembled, are contained into holding fixture (fixed part) properly shaped. Upon reaching the melting temperature of the materials, the circular motion must finish within 0.5 seconds.

The spin welders produced by Sirius Electric, are equipped by a microprocessor for the control and management of the welding cycle.
Programs are available for time, amplitude and quote setting, with torque control and angle stop. Programming is simple and fast and the different menus area available by following simple instructions.

The construction of standard welding machines, has allowed us to achieve a high quality and welding reliability. It’s possible to realize special welding machines designed and manufactured to solve particular assembly’s problems.
It is important to point out that, the relationship and cooperation between the user and the manufacturer of the special machine, is crucial.
Our spin welders are equipped with proportional valve, for the control and regulation of the thrust pressure. In this technology, the design of the welding joint, is simpler but has always to be designed in accordance with the technical specifications required by the customer.