The influence of temperature on the quality of PET preforms

Temperature plays a vital role in the production of PET preforms. Proper temperature control during the injection molding process ensures that the final product meets desired quality standards. Both excessively high and insufficient temperatures can pilot defects, impacting the performance and reliability of PET preforms.

When the processing temperature is too high, the material properties of PET are significantly affected. Excessive heat can cause several issues, such as:

Excessive Softness: PET preforms become too soft, resulting in a product that lacks the strength required for practical applications.

Thin Walls: High temperatures may pilot the material flowing too easily, resulting in thinner walls, which can compromise the structural integrity of the preform.

High Transparency but Weak Durability: While the preform might appear highly transparent, the material becomes brittle and is more prone to cracking or deformation under stress.

Unreliable Usage: Performs produced under excessively high temperatures often fail to meet performance expectations, making them unsuitable for use in applications such as bottle manufacturing.

To mitigate these issues, careful monitoring of the melt and mold temperatures is essential, ensuring they remain within the ideal range for PET processing.

Low processing temperatures also present challenges during PET preform production. Key problems include:

Incomplete Filling: Insufficient heat may result in the material not flowing properly into the mold, pilot incomplete preforms with uneven shapes.

Poor Transparency: PET preforms processed at lower temperatures often have a foggy appearance, reducing their visual clarity and aesthetic appeal.

Thicker Walls with Reduced Strength: In some cases, preforms may have walls that are unevenly thick. Despite the thickness, the strength of the preform may still be inadequate due to improper material crystallization.

Dimensional Inaccuracies: Insufficient temperatures can cause distortions in the preform’s shape, making them unsuitable for further processing into bottles or other products.

Maintaining the correct temperature range ensures proper flow, crystallization, and shaping of PET preforms, ultimately producing a reliable and aesthetically pleasing product.

Temperature directly influences the melt viscosity, crystallization rate, and material flow of PET during injection molding. Proper temperature management ensures that the material fills the mold uniformly, crystallizes correctly, and achieves the desired mechanical and optical properties. By adhering to the recommended temperature range for PET, manufacturers can small defects, reduce material waste, and achieve consistent quality in production.

The appearance of PET preforms is an essential indicator of their quality. Below are some key standards used to evaluate preforms:

The mouth and neck region of the preform should meet the following criteria:

The end surface must be flat and uniform.

Threads should be fully formed without gaps or deformations.

There should be no crystallization defects, material overflow, spinning, or bubbles.

No stains or oil residues should be visible on the internal or external surfaces.

These standards ensure that the neck and mouth area is compatible with bottle capping and sealing systems, preventing leaks or operational issues.

The body of the performer should exhibit:

A smooth and uniform surface with no visible defects, such as bubbles, black spots, or scratches exceeding 20mm in length.

Absence of fogging or whitening, which may indicate improper crystallization.

Consistent color for colored preforms, without noticeable color differences or streaks.

These criteria ensure the preform has a visually appealing appearance and retains the necessary durability for further processing.

Temperature is a critical factor that greatly influences the quality of PET preforms. Both excessive and insufficient temperatures can result in defects that compromise the performance and appearance of the final product.