Advantages of ultrasonic welding: faster, safer, cleaner, more efficient
Faster, safer, cleaner, more efficient, more environmentally friendly, more precise, more transparent,… it’s a long. Ultrasonic technology is gaining acceptance in many industries. No wonder, because hardly any other technology can be used in such a variety of ways with the highest precision and transparency of the welding process.
How does ultrasonic welding work?
Ultrasonic technology has been used for more than 70 years to join thermoplastics (plastics) or thermoplastics with other materials. Furthermore, it is possible to use this technology for cutting and separation welding of a wide variety of materials.
Ultrasonic is generated by high-frequency vibrations: A generator produces a high-frequency alternating voltage from the applied supply voltage, which is converted into a mechanical oscillation by means of a converter. Through oscillating movements (frequency range approximately 20 kHz to 100 kHz) at the sonotrode surface (amplitude), energy is introduced into the components. The energy leads to heating exclusively at the boundary surfaces of the individual components and does not affect the adjacent areas, which means that the component is processed gently. The strong bond is then formed in the short time it takes for the joining partners to cool down. The result of joining is a clean and stable joint seam between the two individual parts, and in the case of cutting and cut-off welding, a clean and flawless cut surface.
Ultrasonic technology is a very good alternative to other joining and separating processes with high efficiency and further future-oriented possibilities. In contrast to other processes, ultrasonic processes – whether cutting, sealing, welding, cut-off welding, punching, riveting – do not cause any damage to the product itself.
The advantages of ultrasonic welding
FAQ ultrasonic and ultrasonic welding
The stringent requirements for medical components in terms of strength, tightness, and near particle-free can be met.
Yes, process validation and stability as well as detailed process monitoring, traceability and data acquisition can also be guaranteed.
Ultrasonic joining technology is at the forefront here and is becoming increasingly popular with all its advantages, see “Advantages of ultrasonic welding“.
The ultrasonic welding process is used, among other things, for processing in laboratory and analytical equipment, hygiene articles, membranes, filters, adapters and connectors.
Unlike other processes, ultrasonic welding does not require any solvents or additives. In addition, the welding tools do not heat up, which eliminates warm-up and cool-down times, allowing for more efficient production operations.
There are different mechanical and thermal methods. In the case of thermal processes, there are basically the following options:
Hot caulking, hot plate welding, hot coil welding, high frequency welding, laser welding, circular welding, rotation friction welding, vibration welding, hot gas welding.
The process is selected depending on the component, the requirements and quality demands, as well as the economy of the process.
The ultrasound is bundled by the energy direction sensor and then fed into the component in a focused manner. This focusing ensures that the energy is used efficiently and a clean weld seam is achieved.
The energy direction sensor, the sonotrode design and the anvil structure all have an influence on the energy focusing.
An oscillating structure consists of a converter, amplitude transformation piece and sonotrode. The converter is the interface between the electrical and mechanical parts. It converts electrical vibration into mechanical vibration via the piezoelectric effect and transfers it to the amplitude and then to the sonotrode. The amplitude transformation piece (also called booster) increases or decreases the amplitude originating from the converter. As the actual welding tool, the sonotrode transmits the mechanical vibration into the component. The oscillating structure is always individually adapted or aligned to the component.
Ultrasonic welding differs from medical applications mainly in the frequencies and powers used. When welding thermoplastics, frequencies between 20 kHz and 60 kHz, and power between 200W and 6000W are used. Medical therapy uses frequencies between 200 KHz and 5 MHz, and diagnostics between 5 MHz and 50 MHz. The power levels used are very low compared to welding.
There are various methods such as: Hot plate welding, filament welding, laser welding, rotation welding, ultrasonic welding, vibration welding, hot gas welding. The process is selected depending on the component, the requirements and quality demands, as well as the economy of the process.
Nature:
Used in animals for location or orientation.
Technical applications:
Welding of plastics and metal, medical technology in diagnosis and therapy, distance measurement on cars, depth measurements in waters, flow measurement in liquids, motion detector, layer thickness measurement, level measurement, material testing, parts cleaning, cutting of biological tissues and many more.
The various ultrasonic technologies are a very economical method – it is used in the following sectors: Automotive, Packaging/Food, Small parts automotive, Textile industry, Medical technology, Consumer goods, Electrical components.
Ultrasonic cutting:
Automotive, packaging technology/food, textile industry, medical technology.
Ultrasonic welding:
Automotive, textile industry, medical technology, consumer goods, electrical components.
Ultrasonic Punching:
Automotive, textile industry, medical technology
Ultrasonic sealing:
Automotive, Medical Technology, Electrical Components
Ultrasonic separation welding:
Medical technology, textile industry, electrical components
Ultrasonic riveting:
Automotive, medical technology, consumer goods, electrical components
A great many, here are the main ones:
+ Very short process times
+ Little to no thermal damage to the component due to cold welding tools
+ Low energy requirement and thus high efficiency
+ No solvents and additives necessary (pure recycling)
+ Constant, reproducible welding results are possible via a wide range of welding parameters
+ The welding tools do not heat up, so there are no warm-up and cool-down times, and the tools can be changed quickly
+ No risk of injury from hot machine parts
+ Short cooling times due to targeted, spot melt formation
Yes, metal welding by ultrasound is a proven process. It is used, for example, to lay copper wires on cable harnesses in the automotive sector. Unlike welding plastics, however, the materials do not mix. It is a friction-based cold welding process.
In principle, joining the same plastics, e.g. PA to PA or PA to PA GF, is the optimum solution. However, some different plastics can also be joined together, e.g. PC – PMMA – ABS. When riveting or bonding, different materials can also be joined together.
Depending on the material used and the design of the joining partners, a welding process including cooling time can take from approx. 100ms to approx. 3s.
In ultrasonic welding, only the joining zone of the component heats up, the matrix of the polymer mixes and is dimensionally stable after cooling.
Here, thermoplastic materials can also be joined with non-thermoplastic materials. Only one of the joining partners melts. This is then a non-positive connection. A sonotrode with a contour matched to the riveting process melts the rivet and reshapes it in such a way that the second material is frictionally bonded.
All thermoplastics can be processed with ultrasonic riveting. Joints are possible between identical or different thermoplastics, as well as between thermoplastics with non-thermoplastic materials.
A vibrating sonotrode cuts the material (nonwoven or similar) on an anvil. Due to the design of the anvil contour, the edge seams of the material are welded simultaneously. It is usually a discontinuous process.
Nonwovens and fabrics with a thermoplastic content can be cut and edge welded.
Fabrics with or without a thermoplastic component can be sealed onto a thermoplastic material. Only one of the joining partners melt. A vibrating sonotrode is placed on the material to be sealed and causes the underlying thermoplastic matrix to melt. This penetrates into the fabric and joins the two materials in a force-fit.
Thermoplastic films, coated substrates, cups, trays, bags and tubes are sealed using ultrasound.
A sonotrode works against a stencil. The stencil is designed exactly to the punching contour. Now the sonotrode is guided through the material to be punched in an oscillating manner. The use of ultrasonic reduces the force required for punching and increases the punching quality.
All thermoplastics up to approximately 10 mm thick can be processed with ultrasonic punching. This is even possible in a painted state. In addition, fabrics, nonwovens and foils can also be punched.
The energy required to melt the components is introduced by a sonotrode via mechanical vibrations. The parts transmit the introduced energy to the welding plane. The materials are mixed and then are dimensionally stable after a cooling period.
All thermoplastics, regardless of whether they have an amorphous or semi-crystalline structure, can be processed with ultrasonic welding. Examples: PS, PVC, PMMA, PC, SAN, ABS, PE, PP, PIM, PA, NFPP, etc.
A vibrating sonotrode cuts the material (nonwoven or similar) on a freely mounted anvil. Due to the design of the anvil contour, the edge seams of the material are welded simultaneously. This is usually a continuous process.
Nonwovens fabrics and films with a thermoplastic content can be cut. In addition, foodstuffs such as cheese or pastries, even in a frozen state.
In technical applications, the vibrations are generated by means of piezoelectric ceramics. In this process, a sinusoidal alternating voltage is converted into a sinusoidal mechanical vibration.
Vibrations with a frequency above the range audible to humans > 20 kHz.
