HF / RF sealing plastic-to-plastic

The advantage of High Frequency sealing for blister packaging is the strength of the sealed flanges. The heat builds up evenly, in a very controlled way, from the inside of the plastic and the dosage of energy can be set very accurately. High Frequency sealing is also called Radio Frequency sealing. HF / RF sealing creates a bond that is equal or greater in strength than the material itself. The seal is consistent, nearly clear and uniform in appearance.The principle of High Frequency sealing is based on electro-magnetic heating of non-conducting materials such as plastics. During the sealing process, the plastic layers are joined under light pressure between electrodes that are connected to a high frequency power generator. The molecules in the plastics start to vibrate and this vibration heats the plastic up to a temperature where the welding of the two layers takes place. The changing polarity of the HF waves passing through the plastic generates heat – just the right amount, very quickly. After the sealing cycle, the HF energy is shut off while the equipment holds the plastic sheets together for a very short time to cool under pressure.