How does ultrasonic vibration melt plastic?

Ultrasonic welding is a technology that uses ultrasonic vibrations to join components made of thermoplastic resin and other materials.
Thermoplastic resin refers to plastics that soften when Because this method allows plastic materials to be joined without the use of adhesives, tapes, or staples, it is considered a safe, reliable, cost-effective, and highly efficient solution. As a result, it is widely used in various industries and applications.

▽Table of Contents

• How does ultrasonic vibration melt plastic?
• Mechanism of ultrasonic welding
• Key features of ultrasonic welding
• Features of Ultrasonic welder QP-01 and L-QP-01
• Differences between Ultrasonic welder QP-01 and L-QP-01

▽How does ultrasonic vibration melt plastic?

Ultrasonic vibration refers to high-frequency vibrational energy—specifically, vibrations that occur more than 20,000 times per second (20 kHz or higher). In ultrasonic welding, these vibrations are transmitted to overlapping plastic components, generating frictional heat that melts and bonds the materials together. In other words, it is not external heat that melts the resin, but the vibration itself that causes the melting.
Ultrasonic welders offer several advantages: they are cost-effective as they require no adhesives or tapes, efficient due to their ability to weld instantly, and safe because they do not use chemical agents. Unlike thermal welders, ultrasonic welders do not use heated plates, reducing the risk of burns.

Ultrasonic technology is utilized not only in ultrasonic welders but also in various other applications, such as ultrasonic cleaning machines and ultrasonic cutters.

▽Mechanism of ultrasonic welding

１．Generation of Vibrational Energy
The ultrasonic generator produces ultrasonic vibrations.

２．Transmission of Vibrations
The vibrations are transmitted to the joining surfaces of the parts through the horn.

３．Heat Generation and Melting
The fine vibrations generate frictional heat, causing the plastic to melt.

４．Cooling and Solidification
When the vibrations stop, the melted areas quickly solidify, completing the bonding process.

▽Key features of ultrasonic welding

・Efficient： Welding is completed within seconds, making the process highly efficient.
・Energy-efficient: Power is only required for the brief moment of welding, resulting in low energy consumption.
・Cost-effective: No need for additional materials such as adhesives, tapes, or staples, which improves overall cost performance.
・Safe method: Since no chemical adhesives are used, the process is safer and carries a lower risk of burns compared to thermal welding.
・Compared to Heat Welding: Ultrasonic welding offers faster bonding speed and lower burn risk, enhancing safety. It can be used immediately once powered on. Heat welding requires external heat to be applied and transferred to the joint, which takes more time to melt the material. In contrast, ultrasonic vibrations instantly reach the joint, minimizing welding time
・Compared to Adhesive Bonding: Adhesive bonding requires a curing time ranging from several minutes to hours. Ultrasonic welding completes bonding within seconds, enabling more efficient operations. Additionally, ultrasonic welding does not involve chemical substances, increasing safety.

▽Features of Ultrasonic Welder QP-01 and L-QP-01

Asahi industry manufactures and sells Ultrasonic Point welder QP-01 and  Dot line welder L-QP-01.
We also offer a lineup of cordless, rechargeable models. These devices are used for sealing takeout food packaging containers, blister pack packaging, bag packaging of parts in factories, and welding various types of plastics.

With over 20 years of experience in selling ultrasonic welding machines, Asahi industry is committed to developing user-friendly ultrasonic welders that meet the diverse needs of our customers.

Features of Ultrasonic Welder QP-01 and L-QP-01
・Compact: Mini ultrasonic welder with a compact body.
・Less Fatigue: Ergonomically designed handpiece allows easy gripping; welding is completed in just a few seconds with light force. Compared to a stapler, it requires less effort, reducing fatigue.
・User-friendly: No complicated settings required; simply turn on the power and set the welding time. Easy for anyone to operate.
・Easy to Work With: The welding horn is visible at the tip of the handpiece, allowing clear visibility of the welding point. This helps maintain high work efficiency and quality.
・Powerful Welding: Uses combined vertical and horizontal vibrations to weld plastics strongly.
・Versatile Applications: Spot welder QP-01 excels at welding thicker materials like plastic clamshell packaging, while Dot line welder L-QP-01 is ideal for thin materials such as films and non-woven fabrics (*performance may vary depending on material type and thickness).
・Cordless Option: Convenient cordless models are available for use in locations without nearby power sources or for portability.
・Made in Japan: We provide products with trusted, reliable quality.
・Supports International Voltages: Compatible with 100–240V power supply.　We also offer model that comply with European CE safety requirements.

▽Differences between Ultrasonic welder QP-01 and L-QP-01

Ultrasonic Point welder QP-01 and  Dot line welder L-QP-01.

Both Ultrasonic Point welder QP-01 spot welder and Dot line welder L-QP-01 are ultrasonic machines used to weld thermoplastic resins. The primary difference is in the shape of the welding horn, which results in different welding patterns.

Point welder QP-01, often referred to as an “ultrasonic stapler,” performs spot welding one point at a time, leaving small semicircular weld marks.
In comparison, Dot line welder L-QP-01 creates a dotted line weld. Its horn is shaped like a wheel and moves sideways across the material during welding.

Dot line welder L-QP-01 can weld a wide area in one pass (in a line), but it is less suitable for thicker materials such as blister packs. Point welder QP-01, welding one point at a time, is better suited for thicker materials. Conversely, when welding thin films with Point welder QP-01, the single spot welds may result in weaker seals that can peel off. Dot line welder L-QP-01, by welding over a wider dotted line, can provide a more stable seal for thin materials.

Depending on the application and material, users can choose between Point welder QP-01 and Dot line welder L-QP-01.

Model	Point welder QP-01	Dot line welder L-QP-01
Welding Horn
Sealing Pattern	Spot (Semicircular shape: 6×3 mm)	Dot line
Welding Method	Seals one point at a time	Seals in a line by sliding horizontally
Optional Attachments	None	Straight-line tip for spot welding
Oscillation Frequency	57kHz
Max Output Power	20W
Power Supply	100V 50/60Hz
Country of Manufacture	Japan
Reference Video

Note: The weldability and strength of ultrasonic welding may vary depending on factors such as the type and thickness of the material.
We are pleased to offer complimentary welding tests using your material samples.
If you are considering the purchase of our Ultrasonic sealers, we would be happy to assist you.

Asahi industry’s Ultrasonic welding machines

Ultrasonic point sealer QP-01

[Corded] https://asahi-packaging.com/products/quppa/
[Cordless] https://asahi-packaging.com/products/qpb-01/

Ultrasonic dot-line sealer L-QP-01

[Corded] https://asahi-packaging.com/products/ultrasonic-dot-line-sealer-l-qp-01-for-synthetic-fiber-materials/
[Cordless] https://asahi-packaging.com/products/ultrasonic-dot-line-sealer-l-qp-01-for-ironer-guide-tape-welding-cordless-type/

Contact
https://asahi-sg.co.jp/inquiry/

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