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Automatic blister packing machines are of 2 types
Hot-forming blister packing machine
A blister packaging machine creates a cavity known as a blister. The blister resembles the shape of the product to be packed. The blister is produced in plastic or aluminum foil which is in roll form. The operations include
Pack Cutting or pack punching of filled and sealed web into strips of desired size – Once the web is sealed it goes to the cutting station which has a cutting tool called a pack punching tool. The web is punched between a die & a punch to cut out pack strips of desired dimension & shape.
Unwinding of forming foil and sealing foil for taking position on forming sealing & cutting stations – This event in 1 cycle of operations can be considered the first operation. Forming foil & sealing foil unwind from their respective rolls. Forming foil with pockets of the shape of products on it & with products filled in pockets converges with sealing foil just before the sealing station.
Forming of cavities also known as blisters in which the product is placed before the pocket is sealed – As the name suggests in hot forming blister packing (transparent strips) the unwound foil gets pressed between two heater plates which are Teflon coated. In the next cycle, the hot foil which has become soft due to heating goes to the forming tool held in the forming station. The forming tool has pockets that are shaped like the product. Air at the required pressure is blown on the soft foil so that PVC foil takes the shape of the pockets in the forming tool. Simultaneously the hot foil with pockets formed in it is cooled using cold water circulating through the forming tool. In the case of cold-forming blister packing as the name suggests pockets are formed by force applied on the cold foil. Here when the foil reaches the forming tool it is pressed between two plates. The top plate has plugs mounted on it which are of the shape of pockets to be made on foil while the bottom plate has pockets of the desired shape resembling the shape of the product. When the plug is pressed on the cold foil with force pockets are formed on the foil web
Dispensing of product in the blisters also known as manual feeding or automatic feeding system – In manual feeding products are placed manually in the formed pockets of foil web. In automatic feeding, the product is poured into the vibrator. Due to vibratory motion product circulates in the vibratory unit bowl & in this process of circulation product passes through the top chute into the spring where its direction is oriented by the springs so that it can enter the lower chute in the proper direction. From the lower chute product enters a rotating drum with pockets of the shape of the product. Product coming from the lower chute is collected in the pockets of the rotating drum and is placed in the pockets formed on the wen of foil. Once the product is collected in the pockets it moves toward the sealing station.
Sealing the blisters effectively safeguards the product until it is ready for use, ensuring its protection and quality – the web of foil with pockets formed on it & the web of sealing foil converge & meet just near the sealing station before entering the sealing station. Once they enter the sealing tool held in the sealing station both the foils are pressed between a hot brass heater plate & an aluminum plate, both these plates have knurling on them due to which sealing foils seal the forming foil with product inside it.
