Impulse vs. Constant Heat vs. Band Sealers Explained

Three ways to seal a bag with heat

All three machine types melt the inner layers of a bag together with heat and pressure. They differ in when and how the heat is applied. An impulse sealer heats only for a moment while the jaws are closed. A constant heat sealer keeps its jaws hot all the time. A band sealer carries the bag through a heated zone on moving bands, so bags are sealed continuously. Each method suits different bag materials and volumes.

Impulse sealers

In an impulse sealer, a thin heating element sits under a Teflon cover on one jaw. When the jaws close, a short pulse of current heats the element, the film melts, and the seal cools under pressure before the jaws open. Because the seal cools while it is clamped, it sets cleanly.

Impulse sealers need no warm-up and use power only during the seal. The jaws are not hot at rest. They are the standard choice for polyethylene (PE) and polypropylene (PP) bags. Seal widths range from round wire, which seals and trims, to 2, 5 and 10 mm flat seals.

Examples are the AIE FS Series stainless steel foot sealers, the AIE A1 Series semi-automatic tabletop sealers and the AmeriVacS AVP pneumatic sealer. For thick and gusseted bags, double impulse sealers such as the AIE FD Series heat from both jaws.

Constant heat sealers

A constant heat sealer, also called a direct heat sealer, has jaws that are heated continuously to a set temperature. When the jaws close, the heat flows into the material right away. Many models press a mesh or line texture into the seal.

Constant heat is the better choice for materials that need steady heat to fuse: aluminum foil laminated bags, coated and metallized films, cellophane and polycello films, and thick gusseted bags. The jaws need a warm-up period; on the AIE-602CH, AIE gives about 5–10 minutes to reach up to 392 °F (200 °C). Because the jaws stay hot, operators must take care, and the sealer should not be left on unattended.

Band sealers

A band sealer, or continuous sealer, grips the open end of the bag between two moving bands and carries it past a heating block, then a cooling block. An embossing or printing wheel can add a code. The bag leaves the machine sealed, and the next bag follows without a pause.

Band sealers suit higher volumes and long runs of the same bag. Horizontal models seal bags fed flat; vertical models seal bags standing on a conveyor, which keeps powders and liquids away from the seal. The AIE B6 Series comes in both versions; the AIE 881BS and 882BS are stainless steel models.

The three methods compared

Choose by bag material first

The material of your bag is the deciding factor. Plain PE and PP bags seal cleanly on impulse sealers. Foil laminated coffee bags, metallized snack bags and coated films usually need constant heat or heat from both jaws. Gusseted bags have four layers at the folds, so they need more heat and a wider seal. If you use several materials, test each one, or choose a machine that can handle the most demanding one.

Then choose by operation

Hand and foot operation suits low to medium volumes; a foot pedal keeps both hands free for the bag. Semi-automatic sealers close the jaws on a timer, so the operator only feeds bags. Pneumatic sealers close the jaws with compressed air, giving the same pressure on every seal. Band sealers are the step for continuous high volumes.

Seal width and appearance

A narrow seal is enough for thin PE bags. Wider seals look more finished and suit thicker material. Mesh and line textures add grip and a professional look on retail bags. A round wire seals and trims, leaving a neat edge.

Matching the method to your volume

A shop sealing a few dozen bags a day needs a simple impulse sealer. A small producer sealing hundreds of foil coffee bags needs a constant heat foot or semi-automatic sealer. A line filling bags on a conveyor needs a band sealer. Count your bags in the busiest hour and size the machine for that.

Common mistakes

The most common mistake is choosing the sealer before checking the bag. A machine that seals PE bags perfectly may leave weak seals on a foil laminate. The second is setting the heat too high to make up for a worn Teflon cover or a dirty jaw, which burns the film. The third is underestimating volume: an operator who seals all day on a hand sealer tires, and seal quality drops late in the shift. Test with your real bags, keep the jaws clean, and size the machine for your busiest hour.

Safety at the sealing station

Impulse sealers have no hot jaws at rest, which makes them easy to use at shared stations. Constant heat jaws stay hot, so keep hands away from the jaws and switch the sealer off after use. Band sealers have moving bands; keep loose clothing and fingers away from the infeed. Read the manufacturer's manual for your model and train new operators on the first few bags.

Maintenance

On impulse sealers, the heating element, its Teflon cover and the silicone pad on the opposite jaw wear with use and are replaced regularly. Constant heat jaws need cleaning to remove film residue. Band sealers wear their bands and heater elements. Keep spare parts for your model on hand.

Recommended Equipment

Impulse sealers: the AIE FS Series, the AIE A1 Series and the AmeriVacS AVP. Constant heat: the AIE-602CH. Band sealers: the AIE B6 Series.

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