A blister machine is a piece of equipment capable of creating preformed packages that can be used to seal items such as food, medicine and various consumer products. There are two primary methods a blister machine can use to accomplish this: thermoforming and cold forming. Some machines are only capable of using one of these methods, while others are multipurpose devices. Most blister machines use polyvinyl chloride (PVC) to form the packaging, though other materials can also be used. Blister machines are also capable of creating slightly different types of packaging, such as pharmaceutical blister packs with push-through backs and clamshell cases used to hold consumer goods.
There are two main ways a blister machine can form sheets of material into packaging. Thermoforming is a technique that involves heating sheets of PVC prior to insertion into a blister machine. This is typically achieved by passing the sheets between upper and lower heating plates. When a sheet enters a thermoforming blister machine, it is soft and pliable and can be forced to take on the shape of a mold through the application of pressure. In some cases, a mechanical stamp will be used in addition to the application of pressure, particularly when the shape of the mold is difficult or complex.
The type of packaging created by thermoforming can be used in many different applications. Some blister machines that use this technique are designed to create pharmaceutical blister packs. This type of packaging typically contains separate blisters for each pill and has push-through foil or paper on the back side.
Other blister machines are designed to create the type of clamshell packaging often used to hold consumer goods. These machines will typically press out each side of the clamshell individually, after which they can be thermally sealed. A thermoforming blister machine can also create one-sided blister packs that are then attached to paperboard cards.
Cold forming is a technique that does not involve any application of heat. Unlike the thermoforming method that uses clear PVC, this technique uses thin sheets of laminate film that contain aluminum. In order to create packaging out of these sheets, a blister machine will typically use a stamp to force it into a form. The aluminum-based film will tend to stretch and retain the shape after the stamp has been removed. This type of blister pack is typically used to contain pharmaceuticals, since the aluminum-based film tends to prevent moisture from entering the packaging.