How to Sonic Weld Flexible PVC

Many types of tubes are ultrasonic welded on one end.

Sonic or ultrasonic welding of plastics uses high frequency acoustic sounds to rub the pieces of plastic together at high speeds, creating friction and heat. This melts the two pieces of plastic together. Because different plastics have different melting temperatures, you can only weld like plastics together. Flexible PVC plastic can be welded, but only to other flexible PVC. This method is frequently used to close plastic tubes to seal in a product. Depending on the technology of the ultrasonic welding machine employed, the welding process is fully automated or manual, which uses a foot pedal to clamp the sides together before the sonic weld is applied.

Things You'll Need

• Grade 5 earmuffs
• Ultrasonic welder

Instructions

1. Put on grade 5 earmuffs to protect your hearing. Some machines are louder than others, but hearing protection should be worn with any ultrasonic welder.

2. Place the flexible PVC on the machine's base.

3. Set the dial or the digital reading to the appropriate frequency. Flexible PVC can typically be welded at 4.5 KHz.

4. Close the machine by hand press or foot pedal, if necessary. Activate the welder by flipping the "On" switch or pressing the button. On many ultrasonic welders, this requires pressing a large green button on the front of the machine.

5. Allow the welder to weld the flexible PVC. It will stop automatically once the plastic has been heated to the proper temperature. Remove the PVC, but do not handle the weld line for several minutes to allow it to cool.

References

• The Plastics Distributor and Fabricator: The Basics: Plastic Welding
• YouTube: Ultrasonic Plastic Tube Sealer
• YouTube: Manual Plastic Tube Sealer