Induction Cap Sealing Machine

Induction sealing, or cap sealing, is the process of heating a hermetically seal with an inner seal, usually the top of a glass or plastic container. This process of sealing happens after the container has been filled and capped.

An induction cap sealer with conveyor is where the cap seal is automatically provided to the bottler with an aluminum foil liner already inserted. There is a variety of liners that can be used, with the typical induction liner being multi-layered.

The top layer of the liner is a paper pulp that is normally spot-glued in the cap. A wax layer is next, which is used to bond the pulp to a layer of aluminum foil. The final layer is a polymer film that is laminated to the foil.

After the cap is applied, the container passes under an induction coil that emits a circular motion electromagnetic field. When the container passes under the induction coil, the aluminum foil liner, which is highly conductive, begins to heat up due to the eddy currents (a circular movement).

The heat melts the wax and the polymer film which then coats the lip of the container. When cooled, the result is a product with a hermetically sealed container. Neither the product nor the container are harmed. The heat generated does not cause any damage.

However, if for some reason it does overheat, the foil can cause damage to the seal and to any other protective barriers. This can result in faulty seals, so it is important to insure proper sizing of the induction sealing process, which is crucial for determining the exact system necessary for a particular product run.

Sealing can also be done with a hand held unit. This more recent development suits a small number of applications which better allows for induction sealing to be to apply to a container without the need for any closure. In this case, the foil comes pre-cut or in a reel. When in a reel, it comes already die cut and is easily transferred to the containers neck.

When the foil is in place, the seal head presses it down, then the induction cycle begins where the seal is bonded to the containers neck. This process is called direct application induction sealing. The final result is a well sealed product.

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