The seal is the part of the package that fails first, so the sealing technology matters more than any headline speed. Three approaches dominate form-fill-seal machines: heat sealing (the default), ultrasonic sealing (for contaminated or sensitive films) and long-dwell sealing (for high-barrier and MAP packs).
Heat sealing
Heated jaws melt the film together under pressure. It is the most common and cheapest method, and it scales to very high speed.
- Force control: Rovema Premiumseal programmes sealing force up to 6,000 N, giving repeatable seals on recyclable films.
- Continuous band: GEA Smart Sealing System seals on a continuous metal band for up to one million bags without stopping (claimed +20% throughput).
- Limit: product dust or liquid in the seal area weakens the seal, because the film must melt cleanly.
Ultrasonic sealing
High-frequency vibration generates heat inside the film itself, so the seal forms even when the sealing area is contaminated with product.
- Availability: offered as an option on GEA SmartPacker CX400 and Mespack HCM; Rovema also lists ultrasonic sealing.
- Best for: powders and liquids that contaminate the seal area, or films that are temperature-sensitive.
Long-dwell sealing
The jaws stay closed longer, which suits thick, high-barrier or laminated films that need more time to reach a hermetic seal.
- Example: PFM Tornado LD is a long-dwell flow wrapper up to 100 packs/min for hermetic, gas-tight seals.
- Best for: MAP and high-barrier packs where a weak seal means the modified atmosphere leaks out.
How to choose
Ask the supplier to demonstrate the seal on your film and your product, at production speed. If the product dusts or the film is thick and barrier-based, ultrasonic or long-dwell usually wins over a plain heat seal. If the line is high-speed and clean, a well-controlled heat seal is the most economical.
Last verified: August 25, 2026.