Ultrasonic welding (USW) uses high-frequency sounds that are generally not heard by humans but instead perceived as vibrations. These high-frequency sounds cause rapid vibrations within the materials to be welded. The vibrations cause the materials to rub against each other which creates friction. The friction in turn creates the heat needed at the contact area of the surfaces of the two materials causing them to bind together.
This process has been used since 1940. Through the years, the process has been continually developed and refined and is now a popular method of welding plastics.
What Are Some Benefits of Ultrasonic Welding?
As with almost all types of welding, there are some benefits and drawbacks of ultrasonic welding. Some benefits include:
- The welding is done at lower temperatures than most other methods.
- It is a more economical process since it requires less heat, and less fuel is expended. Also, there is no need for additional materials that are required by other welding processes.
- It is faster. The weld occurs in fractions of a second. This allows for mass welding projects which can reduce operations costs.
- It bonds plastic better than glue.
- Welds are strong and durable.
- The process can be used to weld dissimilar materials.
- The process is fast, reliable, and provides a high-quality weld.
Drawbacks of Ultrasonic Welding
Despite the many benefits, there are some drawbacks to ultrasonic welding.
- The welder cannot hear the sound and only feels the sound as vibrations. This high-pitched frequency can do damage to the hearing unless the ultrasonic welding machine is safely enclosed or the welder wears hearing protection.
- The weld depth is less than a millimeter, so the process is only best for very thin metals or plastic. Even with plastic, it is not a good technique for welding hard and strong thermoplastics.
- Weld sizes are limited and ultrasonic welding is not suitable for joints larger than 150 mm.
- Ultrasonic welding machines and equipment are expensive.
- USW is only used for lap joints—joints that overlap each other on a flat surface. Therefore, it is not a suitable process for welding edge joints, tees, or corners.
What Metals Can Be Welded Using Ultrasonic Welding?
Ultrasonic welding for metals is mainly used for nonferrous metals. This means that they do not contain iron. That includes aluminum, copper, and nickel. Pure ferrous materials, that contain at least 50 percent or more iron, are not suitable for ultrasonic welding.
It is also frequently used for joining aluminum and copper. This is due to the increasing need for lithium-ion batteries. These are used in the burgeoning electric automotive industry. Additionally, aluminum and copper are used for cable connections in the electronics industry.
Ultrasonic welding of the metals is ideal because of the short weld time, the energy efficiency of the process, and the “durability of the end products.”
Use of Ultrasonic Welding for Plastic Components
Ultrasonic welding is an ideal technique for welding plastics. Within seconds, a tight bond is formed without the use of glue or any other type of bonding material. The process is eco-friendly in that it uses very little energy which also makes it a cost-effective process.
The process is used with plastics that don’t melt but soften which makes it work best with thermoplastics, which soften over a wide range of temperatures. The best use of ultrasonic welding is to join parts made of the same plastic material which means they have the same chemical makeup and similar melting points.
Some examples of items containing plastic that use ultrasonic welding include:
- Medical devices such as valves and face masks.
- Upper portions of athletic shoes.
- Plastic parts of household appliances.
- Used in many areas of the packaging industry.
- Various automobile parts. For example, in instrument panels, steering wheels, air ducts, upholstery, taillights, bumpers, some engine components, and more.
- Various electronics including computer circuit boards, transformers, electric motors, flash drives, computer disks, and capacitors.
Vern Lewis Welding Supply Is Here to Help!
Vern Lewis Welding Supply offers welding supplies, equipment, repairs, and maintenance as well as welding classes. For your convenience, we have 9 different Arizona locations. Contact us for more information and to see how we can specifically help you meet your welding needs.
Sources:
- https://www.craftechind.com/an-introduction-to-the-ultrasonic-welding-of-plastics/
- https://science.howstuffworks.com/ultrasonic-welding.htm
- https://waterwelders.com/how-does-ultrasonic-welding-work/
- https://www.dukane.com/plastic-welding-process/what-is-ultrasonic-welding/#:~:text=Ultrasonic%20plastic%20welding%20(USW)%20is,into%20high%2Dfrequency%20mechanical%20motion.
