Working principle of automatic blister packing machine.
Automatic blister packing machines are of 2 types
· Cold forming blister packing machine
· Hot forming blister packing machine
A blister packaging machine creates a cavity known as blister. Blister resembles the shape of the product to be packed. The blister is created in plastic or aluminum foil which is in roll form. The operations include
1. 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 as the first operation. Forming foil & sealing foil unwinds from their respective rolls. Forming foil with pockets of shape of products on it & with products filled in pockets converges with sealing foil just before the sealing station.
2. 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 next cycle the hot foil which has become soft due to heating goes to forming tool held in forming station. Forming tool has pockets of the shape of product. Air at required pressure is blown on the soft foil so that PVC foil takes the shape of the pockets in forming tool. Simultaneously the hot foil with pockets formed in it is cooled using cold water circulating through the forming tool. In case of cold forming blister packing as the name suggest 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 is of the shape of pockets to be made on foil while the bottom plate has pockets of the desired shape resembling the shape of product. When the plug is pressed on the cold foil with force pockets are formed on the foil web
3. 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 in 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 lower chute in proper direction. From lower chute product enters a rotating drum with pockets of the shape of product. Product coming from the lower chute is collected in the pockets of rotating drum and is placed in the pockets formed on the wen of foil. Once the product is collected in the pockets it moves towards sealing station.
4. Sealing the blisters effectively safeguards the product until it is ready for use, ensuring its protection and quality – 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 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 seals the forming foil with product inside it.
5. 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 cutting tool which is also called as pack punching tool. The web is punched between a die & a punch to cut out pack strips of desired dimension & shape.
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