Ultrasonic welding

Ultrasonic welding is the process by which two pieces of plastic are joined together through the use of high-frequency acoustic vibrations. During the process, one half of the component is placed on a fixed anvil and the second half is placed on top. An extension, connected to the transducer on the welding machine, called a 'horn', is then lowered down on top of the two components.

Once the horn is in place, a rapid, low-amplitude acoustic vibration is applied to the moulding in a small welding zone. This vibration causes the acoustic energy to be converted into heat energy and the two components are welded together in a short space of time (typically less than one second).

Ultrasonic welding is a highly automated process - our expert team works with you to deliver the finished product you need

Parts that will be ultrasonically welded together are designed with very small amounts of extra material on the join line on one half, with a slight recess in the second half. This means that when the parts are welded together there is sufficient material for the parts to fuse together with a strong joint. The process also means that no additional adhesives or connective parts are needed to create the joint, saving money and making the process quicker to carry out.

The welding information, such as time and frequency, is programmed into the welding machine so that each process carried out is controlled by computer to make sure they are all the same. All an operator needs to do is place parts on the anvil and push a button. The rest of the operation is carried out automatically and the operator simply needs to remove the welded part and install the next component.

Due to the high energy processes that would be involved it is simply too dangerous to weld together large component parts using ultrasonic welding. Even with ultrasonic welding of small components the operator must wear ear defenders due to the acoustic dangers caused by the two parts vibrating together. To weld large parts these vibrations would be substantially larger and the energy involved would be a danger to surrounding operators.

Benefits of ultrasonic welding

• Very neat weld seams
  Due to no additional adhesives or parts being needed the welding joins created with ultrasonic welding are extremely neat and visually attractive. This means the process can be used for joins that will be visible once final assembly has been completed
• High level of quality
  As all of the welding parts of the operation are automated each part produced will be of high quality. The chances of human error is hugely reduced and accuracy significantly increased.
• Low cycle times
  The actual time it takes for a part to be welded is typically less than one second. This means that the loading and unloading of the machine will take up the majority of the cycle time, keeping cycle times to a minimum. This low cycle time means that large batches can be produced in a very short space of time.