Types of Heat Sealing
- Hot bar sealers- have heated tooling kept at a constant temperature. They use one or two heated bars which contact the material to heat the interface and form a bond. The bars have various configurations and can be covered with a release layer.
- Continuous heat sealers- (also known as Band type heat sealers) utilize moving belts over heating elements.
- Impulse heat sealers- have heating elements (one or two) of Nichrome placed between a resilient synthetic rubber and a release surface of film or fabric. The heating elements are not continuously heated; heat is generated only when current flows. When the materials are placed in the heat sealer, they are held in place by pressure. An electric current heats the heating element for a specified time to create the required temperature. the Jaws hold the material in place after the heat is stopped, sometimes with cooling water: this allows the material to fuse before stress can be applied.
- Hot melt adhesive can be applied in strips or beads at the point of joining. It can also be applied to one of the surfaces during an earlier manufacturing step and reactivated for bonding.
- Hot wire sealing - involves a heated wire that both cuts the surfaces and joins them with a molten edge bead. This is not usually employed when barrier properties are critical.
- Induction sealing is a non-contact type of sealing used for inner seals in bottle caps.
- Ultrasonic welding uses high-frequency ultrasonic acoustic vibrations to workpieces being held together under pressure to create a weld.
A type of heat sealer is also used to piece together plastic side panels for light-weight agricultural buildings such as greenhouses and sheds. This version is guided along the floor by four wheels.
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