Ultrasonic sealing: A safe and clean affair

Bosch Product Protection Valves

In principle, two technologies are available on the market for the application of product protection valves: heat sealing and ultrasonic sealing. Both technologies deliver good, reliable results, but they differ in terms of visual appearance, process, speed and flexibility.

Jenny Haase is responsible for the development of packaging materials and consumables at Bosch Packaging Technology. In the following article she shares with us the reasons why ultrasonic sealing is the technology of choice to apply product protection valves.

Which technology do you recommend?

For manufacturers who plan to introduce a new system I strongly recommend ultrasonic sealing. This trend is also reflected in the market. The valves themselves – whether used for heat sealing or ultrasonic sealing – are identical when it comes to functionality and reliability. However, a direct comparison of the two sealing processes shows that there are a number of decisive differences.

Ultrasonic sealing is very gentle on parts and components. Due to the valve‘s particular geometric shape surrounding the joint zone, the welding energy is targeted precisely and only applied locally. The level of thermal stress for the packaging material and the valve itself is very low. The need for holding/cooling times is minimal, if at all necessary, and pressure can be applied to the seam immediately.

In addition to technical requirements, such as strength and tightness, today ecological aspects are becoming increasingly important. Ultrasonic systems are significantly easier to maintain than heat sealing systems.

Another big difference lies in visual appearance. With heat sealing, the weld seam surrounding the internal valve is clearly visible on the outside of the pack, while ultrasonic sealing valves are barely visible. Ultrasonic sealing delivers particularly attractive and discreet results on packaging films with mat lacquer and soft touch surfaces, which are currently very popular. The valve sealing process can easily be adjusted for peelable films (based on the film material) without the formation of angel hair.


Heat Sealing Technology

Valve applied with heat sealing technology

Ultrasonic sealing technology

Valve applied with ultrasonic sealing technology.


Most commonly, machine speed is crucial for manufacturers. The Bosch ultrasonic system, depending on format settings, can achieve up to 80 valve applications per minute (higher cycle times upon request), which appeals to manufacturers of finished bags in particular. These cycle times cannot be achieved with heat sealing.

What advantages does ultrasonic sealing have in terms of processing?

The increasing variety of formats and packaging material calls for a controllable and adjustable process. Process control and process optimization are key advantages of ultrasonic sealing. The ultrasonic welding process can be controlled very precisely. Predefined values are used to monitor each valve during the welding process. If a limit value is not adhered to during the sealing process, an error message is displayed for the concerned product. The relevant bag can then be discharged automatically.

The lower heat load protects the valves and the packaging material. In addition, angel hair formation on the pack is almost nonexistent. Angel hair is a fine PE dust, which frequently occurs in heat sealing.

Overall, one can say that ultrasonic sealing delivers superior quality on all levels compared to heat sealing.

Why should a manufacturer choose Bosch?

As one of the leading manufacturers of packaging equipment, we can offer our customers a wide range of products – from simple valves to complex systems – all from one source. Our global service network delivers excellent support. We have over 30 years of experience in valve technology and provide manufacturers with first-class valves and appropriate applicators. Our ultrasonic sealing systems offer operators the possibility to manage process control and optimization directly via the machine’s HMI. This is not only highly practical, but also unique in the market.

Top 5 reasons for ultrasonic sealing:

1. Excellent visual appearance
2. Great packaging flexibility
3. No angel hair formation – even with peelable packaging material
4. Easy process control and optimization
5. High speed



Jenny Haase, Bosch Packaging Technology
Jenny Haase
Development of packaging materials and consumables
Bosch Packaging Technology
Phone: +49 711 811-57365

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