pet preforms are manufactured through an injection molding process. In order to blow them into bottles, they need to be reheated. The characteristics of PET make it easy to absorb the heat generated by infrared lamps (especially shortwave lamps).
The preform is fixed on two rails or fixtures, and then passes through a tunnel where many short-wave infrared lamps are installed. Depending on the wall thickness of the preform and the blowing capacity (number of bottles per minute), the tunnel will have multiple heating zones. When the preforms pass through the tunnel, they rotate so that the entire preform is evenly heated. The neck of the preform cannot be heated because its shape must remain unchanged. There is a chilled water circulation in the aluminum guide rail, which is used to fix the neck of the preform to ensure that the neck does not become hot.
The short-wave radiation emitted by the infrared lamp is easily absorbed by the PET preform. Some of the radiation passes through the preform and is reflected back onto the preform by a reflector located behind the preform. This way the heat loss is kept to a minimum.
The IR lamp is mounted on an adjustable bracket to provide the flexibility of moving the lamp back and forth. This is to cater to preforms of different sizes and wall thicknesses. A cooling fan is installed in each heating zone to ensure that the infrared lamps and reflectors will not overheat. It is important to keep the end of the lamp cool, otherwise the cable may be damaged.
After leaving the infrared tunnel, the preform moves to the blow molding station, where it is finally blown into the shape of the bottle.
We, DONGHAI YOUNG LIGHT can provide infrared lamps for most PET blow molding machines.