Blow Fill Seal technology is a continuous process carried out on one multi-function machine. The starting point is a supply of polymer granules, which are fed via a hopper to an extruder operating at high pressure (300 atmospheres), and high temperatures (approximately 165C for polyethylene)
Semi molten polymer is extruded in a tube shape, called a parison, until it is the desired length, whereupon the two halves of the mold forming the body of the container to be made are closed. The parison is cut and the mold moves to a second station.
With the aid of vacuum the parison is pulled into shape in the mold and the plastic very quickly cooled by virtue of the coolant flowing through a honeycomb of passageways in the mold segments. At this point filling tubes are lowered and the required dose of product is filled into the container using time-pressure dosing. The filling tubes are withdrawn and the head mold segments close on the still hot upper section of the parison and again with the help of vacuum, the top part of the container is formed.
The whole filling and sealing process takes place in an enclosed volume that is fed with a fast flow of absolute filtered air to provide a sterile environment. The machine itself is also housed in an environmentally controlled room to minimize the bacteriological challenge to the process. Solution to be filled is sterile filtered immediately prior to filling and the air that supports the parison during extrusion is also sterile filtered.
The cycle time is approximately 10 to 12 seconds depending on the size of the container, plastic type and thickness and other variables. Typically for small volume containers in the range 5ml to 10ml, eight to ten will be molded per cycle. The product that leaves the BFS machine has been formed, filled and sealed and is ready for use, requiring only labeling, packing and Quality Control release to be ready for sale.
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