In the PET industry, the relationship between preform design and final container performance is key. The grammage or weight of the preform directly impacts the rigidity, stability, and strength of the container. In Demizon, as specialists in PET preform and plastic containers, we offer solutions designed to achieve the ideal balance between functionality, aesthetics, and operational efficiency.
Table of contents
- What is the grammage in a PET preform?
- Structural impact of grammage
- Choice of grammage according to application
- Customized preforms: beyond grammage
- Relationship between grammage and sustainability
- Conclusion
What is the grammage in a PET preform?
Grammage is the weight, measured in grams, of the plastic bottle preform before its blowing process. This parameter determines the amount of material available to form the walls of the container.
However, when evaluating the actual grammage intended for the structure of the container, the weight of the neck must be subtracted, as this section does not deform or stretch during blowing. Therefore, it does not contribute to the body of the container, but it does influence the total weight of the preform. This difference is key when comparing designs or defining strength parameters.
Structural impact of grammage
The appropriate weight of a PET preform influences:
- Stacking strength: fundamental in distribution lines and prolonged storage.
- Support for internal pressure: key for carbonated beverages.
- Dimensional stability: important in automated filling processes.
- Post-consumer durability: especially in products like reusable jugs.
A poorly calibrated preform can compromise the strength of the container or, on the opposite end, unnecessarily raise resin costs.
Choice of grammage according to application
In Demizon, as one of the leading preform manufacturers in Mexico, we help our clients choose the optimal weight according to their product type, volume, and expected shelf life:
Product type | Suggested weight | Key features |
0.5L bottles | 14 g – 18 g | Lightweight, immediate use |
1L bottles | 21 g – 30 g | Balance between rigidity and weight |
19 – 20L reusable jugs with and without handle | 650 g – 800 g | High strength and durability |
The selection will also depend on the mold design and blowing parameters.
Customized preforms: beyond grammage
Weight is not the only factor that defines the quality of plastic containers. Their final performance also depends on the overall design of the PET preform, the thickness in specific areas, and the proportion between dimensions.
For example, the height of the container should not exceed 2.5 times the size of the preform, as this can affect material distribution and create weak areas.
Similarly, an excessive diameter without structural support can compromise strength, especially in industrial applications or products with internal pressure.
Additionally, the ideal weight also changes depending on the type of liquid or product being packaged:
- A lightweight water bottle can be made with a low-weight preform.
- A bottle for carbonated beverages requires greater weight to withstand the pressure.
- In the chemical or agro-industrial industry, higher weights are used to ensure safety and durability.
In reality, it all depends on several factors: what is going to be packaged, which industry it is intended for, under what conditions it will be transported, and how the product is expected to look to the end consumer.
In Demizon, we understand these variables and provide advice to help you choose the appropriate PET preform, tailored to the specific needs of each client, ensuring functionality, strength, and an optimal presentation according to the target market.
Relationship between grammage and sustainability
A key point today is the balance between strength and sustainability. While a greater amount of material can offer more rigidity, it also increases resin consumption. This is where design and process engineering comes in.
Additionally, many clients consult us about the possibility of integrating recycled PET, which, while feasible, must be considered that depending on the percentage, it could affect properties such as gloss or rigidity.
Conclusion
The weight of the PET preform is one of the most determining factors in the quality of the PET packaging final. Its correct selection allows for obtaining safe, functional, and efficient products in production.
At Demizon, as a supplier of PET preforms and comprehensive solutions for blowing, we develop each piece considering mechanical performance, cost-benefit, and the real market conditions.
Do you need to define the ideal weight for your bottles or jugs? At Demizon, we help you choose the right preform for each type of container.
Contact us today and receive personalized technical advice.