In the PET industry, the connection between preform design and the performance of the finished bottle is critical. The weight—or grammage—of the preform directly impacts the stiffness, stability, and strength of the bottle.
At Demizon, as specialists in PET preforms and plastic bottles, we deliver solutions designed to strike the ideal balance between functionality, aesthetics, and operational efficiency.
The grammage refers to the weight, in grams, of the plastic preform before it goes through the blow molding process. This figure represents how much material is available to form the walls of the final bottle.
However, when evaluating the actual material contributing to the bottle’s structure, it’s important to subtract the weight of the neck finish (the threaded portion), since this part does not stretch or reshape during blowing. While it adds to the total weight of the preform, it does not add to the body of the bottle. This distinction is key when comparing designs or setting strength requirements.
The right preform weight influences :
A poorly chosen preform weight can lead to bottles that are either too weak or unnecessarily expensive due to excess resin use.
At Demizon, one of Mexico’s leading PET preform manufacturers, we help customers choose the optimal preform weight based on product type, volume, and expected lifecycle:
|
Product type |
Suggested Weight |
Key Features |
|
0.5L bottles |
14 g - 18 g |
Lightweight, single-use |
|
1L bottles |
21 g - 30 g |
Balanced strength and weight |
|
19 - 20L reusable jugs (with or without handle) |
650 g - 800 g |
High durability |
Preform selection also depends on mold design and blow molding parameters.
Weight isn’t the only factor determining a bottle’s quality. The final performance also depends on the overall preform design, thickness in critical areas, and proportion of dimensions.
For example: - Bottle height should generally not exceed 2.5 times the preform length to avoid weak spots. - Large diameters without sufficient structural support can reduce strength, especially in pressurized or industrial applications.
The ideal weight also depends on what product will be bottled:
Carbonated drinks require heavier preforms to withstand pressure.
At Demizon, we understand that every application is unique. We help our clients choose the right PET preform tailored to their specific needs, ensuring functionality, strength, and the right look for their target market.
Today more than ever, balancing strength and sustainability is key. While heavier preforms offer more rigidity, they also increase resin consumption. That’s where smart engineering and process optimization come in.
Many customers also ask about incorporating recycled PET. While this is absolutely possible, the percentage of recycled content can affect properties like shine or rigidity, so it’s something to plan for carefully.
The weight of the PET preform is one of the most important factors in determining the quality of the finished bottle. Choosing the right weight ensures a safe, functional, and cost-efficient product.
At Demizon, as a trusted supplier of PET preforms and complete blow-molding solutions, we design every piece with mechanical performance, cost-effectiveness, and real-world market conditions in mind.
Need help determining the right preform weight for your bottles or jugs?
Contact Demizon today and get personalized technical support.