The Manufacturing Process of PET Preforms Explained: A Versatile Plastic Molding Solution
Many of Polyshot’s customers rely on polyethylene terephthalate (PET) preforms to make their plastic molding processes more reliable, efficient, and cost-effective. When it comes to end products and applications, PET preforms are a versatile solution for producing bottles and containers across a wide range of industries. The preforms are injection molded, then manufacturers subsequently use the preforms as a base for their blow molded products.
At Polyshot, we specialize in serving numerous markets that heavily use PET preforms, including:
- Medical Manufacturers and Pharmaceutical Companies – Today’s medical and healthcare industries use PET preforms to produce reliable drug packaging and bottles for pills and liquid medicines.
- The Pet Industry – The ever-growing pet industry relies on blow molded bottles and packaging for food, pet care products, toys, and many other pet accessories.
- Various Consumer Products – Manufacturers of consumer products in a wide range of categories rely on PET preforms for bottles, containers, and packaging. From personal care products and toiletries to the kitchen, garage, and garden, PET preform injection molding is an increasingly popular method.
For new manufacturers or those who are considering expanding into blow molding, as well as for customers who are simply curious about the process, we’ve put together a basic guide to the PET preform manufacturing. It will help you understand how the end products are made, along with the general advantages preforms offer to the plastic molding process.
What Are PET Preforms?
Before delving into the manufacturing process, let’s take a closer look at what exactly PET preforms are. Essentially, preforms are semi-finished products manufactured via injection molding process. They serve as an intermediate step in the production of PET bottles and containers – similar to how cores are used in metal casting, or near net shape (NNS) part manufacturing. As with typical injection molded products, the preform is made by injecting molten polyethylene terephthalate resin into a mold cavity under high pressure.
The resulting preform features a thick-walled, tubular body with a fully formed neck finish, potentially with threads or other fasteners that will later accommodate caps or closures. After cooling within the mold, the preform retains its structural integrity and dimensional accuracy, making it suitable for subsequent stretch blow molding (SBM), where it is reheated and expanded into its final bottle shape.
The most common end product applications include plastic bottles for water and other beverages. However, as we mentioned above, a huge range of other plastic bottles and containers are also commonly made through the use of PET preforms.
PET Preform Manufacturing Explained
The first step is to prepare the PET resin, which comes in the form of small plastic pellets. The raw material is carefully processed and dried to remove moisture, which can otherwise cause quality issues in the molding and curing phases.
Next up is the actual injection molding process. The dried PET resin is fed into an injection molding machine. It is melted and fed into the mold cavity, which has been machined into the exact shape of the desired preform.
On that note, preforms are relatively simple product designs. Unlike more complex injection molded products – which may require thin walls, complex shapes, and intricate pathways – PET preforms are essentially simple shapes that can be made with thick, durable walls to ensure reliability of the blow molding process to follow.
After injection molding, the preform cools, cures, and is ejected from the mold. The product should then be thoroughly checked for quality and dimensional accuracy – any slight error will potentially multiply into costly production issues once the preform is put to use.
Quality Plastic Molding Equipment Solutions Since 1989
Polyshot Corporation specializes in the development of advanced hot runner systems to injection molding companies worldwide. We offer expertise in virtually all realms of plastic manufacturing – from preform production and blow molding to high-precision injection molding. Backed by more than 35 years of innovation and experience, our company continues to help our customers remain at the cutting edge of industry.