Ways Of Manufacturing Preforms

Update: 13-12-2019

Preforms play a very vital role in deciding the strengt […]

Preforms play a very vital role in deciding the strength of the PET Bottle. There are various methods to form a Preform and there are many factors which affect it.

Two ways of manufacturing preforms are popular:

1. One-step method: In this method, the entire process is done in a single integrated machine. Injection molded preform is taken out from the cavity when it is still hot. Since preforms are immediately taken for blowing, there is no risk of surface damage during transportation and storage. Also, there is a significant cost-saving because no re-heating is required. The overall process efficiency achieves less harm to the environment. Especially, for small and medium production lines it is an ideal method. Temperature remains constantly high in this process keeping the material is in an elastic form. Though, high energy consumption is needed to keep it high, there is a significant saving because material has to be heated only once.

2. Two-step method: This process involves two stages, injection stretch blow molding and reheat blow molding. First the preforms are manufactured using injection blowing method. They are stored for later use or sent to packing division for dispatch. Reheat blow molding machines take the preforms and blow the bottles of desired shape. Of course, this method is less efficient as compared to other. Nevertheless, there are advantages of it. Firstly, it helps in planning the operations better. Secondly, this method ensures excellent neck finish and economical use of resins. This method is not energy efficient, but there is significant cost saving because of automation of the process. Medium and large production houses prefer this method because it eliminates the need of manual supervision.

PET preforms are manufactured through the process of molding. Molds of appropriate size and shape are selected and fused PET is injected into it. Blowing process is used to give it the shape of a preform which can be later blown further to make desired shape of containers for beverages, detergents, oil, and thousands of other products. The finish or bottleneck which is the base for manufacturing preform doesn’t change when it is blown in the shape of a bottle.