Impulse Sealers Vs Heat Seals: Which One Is Right For You?

Ideally, specific plastic film materials should have a unique crimp jaw specification for each thickness. Still, a compromise is always needed as machines have to handle a wide range of films without modification or resetting mechanical parameters. Various thickness films keep crimp jaws separated by differing amounts; the limitations on the crimp jaw slants vary, which is shown in the distortion or variability of the seal performance.

Crimp jaws are set to an excellent distance separated, and spring forces or loadings are formed when the jaws are heated at temperatures near the preferred sealing temperature. (generally temperature approx to the melting temperature of the plastic)

PP during sealing

Polypropylene (PP) films have greater extensibility in the MD, typically greater than 150% elongation before the break and approx 70% in the transverse direction (TD). Vertical or Horizontal Form/Fill/sealing (f/f/s) machines function better and provide better seal integrity with transverse jaw grooves to lower the stress in the TD and let more elongation in the MD.

PE, PET, and Nylon (PA)

With their excellent heat stability providing extensive sealing degrees, PET and nylon PA films usually do not create split seals. With PE or cast, PP as the sealant of laminate exploits the easy flow character of the cast and low-melting-point polymers. The melted polymer can flow into crevices and fill voids or holes in the seal. 

With increased filling and packaging speeds, it is required to maintain high temperatures to soften the sealant in a short dwell time. When the FFS speed changes, the high temperature of the sealing jaws harms the film. Lower heat settings are likely with the LTS (low-temperature sealing) coating or should be added with the heat sealing additives, thus avoiding film damage at slower speeds. Such low sealing point temperatures mean a short dwell sealing time is feasible at lower temperatures with crimp jaws, thus bypassing film shrinkage. 

Most seals are considered vital if the film tears when the seal is stretched. Seals have built-in evidence of tampering, but the packages may still be opened effortlessly, particularly in the case of oriented films with their handy tear propagation properties. However, if the seal peels open slightly and absorb the stress without tearing, the pack is still unchanged and resumes to function. Tamper evidence, in this possibility, is less apparent.

What is an Impulse Sealer?

An impulse sealer is a device that uses an electric impulse to heat the jaws of the sealer to a fusion temperature, which causes the material to be sealed permanently by building up heat and pressure. It is beneficial for small parts that require a quick and permanent fixation. 

what is a heat seal, heat impulse sealer

The seal area stays clamped and is cooled beneath pressure. Impulse seals are less wider than hot bar seals but can be doubled up. The impulse process may provide a better seal when little contamination is present. (Such as powder and liquid products) Voltage and duration are varied according to the material.

Sealing PE films with heated wires or strips is common to create welded seals. If the seal is not to be cut through the web, the heating strip has covered so that it doesn’t stick to the molten polymer and destroy the seal.

It is achieved by covering the strip with a release sheet such as PTFE-covered glass fiber woven cloth. The resultant seals gain 100% film strength. Using PE sealing equipment, it is possible to make the same type of seals with coextruded OPP, but the seals are more sensitive to tearing close to the seal due to the expected easy tear propagation caused by high-stress orientation.

Heat Seal

On the other hand, heat seals use heat to soften the material to tap it into place. Afterward, a compression force is applied to seal the joint together.

If required for pouch packing in which you wish to speed up production, but automatic is not an alternative, a continuous and manual band sealer may be for you. A band sealing machine offers many benefits. These machines will rapidly and securely pack many bag materials, giving excellent strength and visual appeal for a good look and reliable performance. It can heat seal any thermoplastic material, including polyethylene (PE), polypropylene (PP), and laminations with foils, such as packets used to hold coffee.

what is a heat seal, heat impulse sealer

These devices are also remarkable for sealing packages that ease electrostatic charge for electronics products. They are perfect for mid- or high-volume sealing. When it reaches packaging, band sealers are so universal and efficient that they might just as well be called bag sealers.

A band sealer machine is straightforward to operate. The person needs to do is feed pouches into the machine’s jaws. In the continuous machine, filled bags carry along on a motorized conveyor belt. The machine shows the top of each bag through the sealing process with PTFE bands.

There are a few things to keep in mind regarding impulse sealers and heat seals. First, impulse sealers work by using a high-speed rotating roll to create pressure and heat on the film. It makes a seal between the film and the object being sealed, broken by the roll’s movement. Heat seals use heat to create a seal between two surfaces. It is done by heating one surface until it becomes soft and pliable, at which point it is pressed against the other surface—the difference in how these two types of seals work are what affects their distortion or variability. The loads on the crimp jaw slopes vary with impulse seals, resulting in distortion or seal performance variability. Heat seals typically offer a more consistent seal, while impulse seals can be more responsive to changes in pressure. Heat seals usually provide a more consistent seal, while impulse seals can be more responsive to changes in pressure.

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Vihaan Nagal

संवेष्टन अभियान्ता | Packaging Engineer | Verpackung Ingenieur *Free time blogger *Believe in packaging reform (say naa to orthodox packaging) My life lies between degradable and non-degradable material.

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