When you open a bottle of over-the-counter medication for the first time, between the twist-off cap and the cotton balls you will likely find a flat disc of foil that must be torn away if you want to get to the pills underneath. That disc is an example of induction sealing, and it is such a reliable indicator of safe packaging that finding a new bottle with the seal already broken is cause for concern.
Induction sealing is a lightweight, effective method to preserve freshness, prevent leakage, and show clear evidence of tampering. In some cases, you may choose to have a seal that pulls away cleanly. This could be preferable for some food products like salad dressing or ketchup where the contents would stick to any remaining portion of the seal in an unpalatable and possibly unhealthy way. In other cases it is better when the seal is very difficult to pull off completely so that any tampering is very obvious (in fact, for medications the Food and Drug Administration requires that such seals “cannot be worked off and reapplied without visible damage.”)
The seals themselves are supplied inside the caps, and they are made of an aluminum foil layer, often sandwiched between other materials. Most often, the aluminum layer is held to the top of the cap with layers of wax, paper and glue. Underneath is a layer of polymer film that will seal the aluminum to the opening of the bottle.
Once the bottles are capped, they are passed under an induction coil which heats the aluminum foil. This heat simultaneously releases the foil from the cap and seals it to the container. Passing the bottle under the induction coil can be done manually with a hand-held device or at greater speeds with a conveyor belt. Most systems today are waterless (air-cooled), which take up about half the space of older water-cooled systems.
While shrink wrapping is a popular and familiar option, and it is useful for bundling several separate items together, induction sealing is still a better option in many cases. Some advantages include:
First, determine how many containers you need to seal, as well as their size and shapes. Look for a system that can accommodate changes in packaging. Even better, see if it can be scaled up as your business grows. Most suppliers can accommodate cap sizes from 15 to 120 mm, at speeds of up to 180 conveyor feet per minute, as shown in this chart.
Next, determine how much power you will need. Induction sealers can require between 0.5 kilowatts to 6 kilowatts, depending on the number of containers you need to be sealed per minute.
Talk with your supplier before you make any purchase and let them know all the details of your product and its packaging. Inquire if they will help you solve problems over the phone, or if you must always wait for a service person. Also, see if their power supplies are separate from their sealing systems, so you will not have to send the entire machine back if only one part needs to be replaced.
Once you have your induction sealing system set up, take the time to find your best operating window. As illustrated in this video, using too little heat will result in no seal or only a partial seal. Too much heat will not only visibly damage your container, but can also cause the seal to fail days or weeks later.
Should you choose to use induction sealing with your packaging, following these tips can help keep your product secure while giving your customers greater peace of mind.
Call us at 219-575-7493 or visit our page here to discuss our capping solutions and how they can fit in with your induction sealing system. More tips on choosing an induction sealing system can be read here.