THERMOFORMING – A low cost alternative to Blow molding
Until now, plastic bottles have been produced primarily via blow molding of preforms. With its newly developed Bottleformer BF 70, Illig recently introduced a low-cost alternative for production of bottles for yogurt, juice, isotonic beverages and bread spreads.
The polystyrene film used to produce the bottles is drawn from a roll. Contact heater plates warm the film in steps to the optimum forming temperature. Following this, the bottles are formed using sterile compressed air and then stamped out of the web. The skeleton that remains after stamping is uncontaminated polystyrene and can be recycled.
The bottles are sealed with preformed aluminum plugs that are slightly larger in diameter than the opening in the neck of the bottle. The outer rim of the thermoformed bottles provides a smooth surface for sealing, ensuring that the bottles are sealed tightly.
Moving segments in the thermoforming molds permit production of bottles with undercuts. According to information from the company, a very uniform wall thickness distribution is achieved in spite of the small initial surface area and high draw ratio. Moreover, the thermoformed bottles have only half the weight of a blow molded bottle. There is no visible difference between the blow molded bottle and the thermoformed bottle.
The machine operates at 25 cycles per minute. At 20 bottles per cycle, the overall output is about 30,000 bottles per hour. This matches the output of a conventional fill and seal machine.
