How quality control works in an ISO/IEC 17025 laboratory

For a preform or film producer, consistent resin matters more than record-breaking specifications: if viscosity or colour changes from lot to lot, the line has to be re-tuned and rejects increase. That is why "how does the supplier control quality?" is one of the first questions when choosing a plant.

What ISO/IEC 17025 is

ISO/IEC 17025 is the international standard for the competence of testing and calibration laboratories. Accreditation to it means that an independent body has assessed the laboratory and confirmed that:

• tests are carried out using documented and validated methods;
• equipment is calibrated and measurement results are metrologically traceable;
• staff have the required qualifications;
• results are reliable and reproducible, and the laboratory's work is regularly audited.

In other words, accreditation is external confirmation that the laboratory's results can be trusted. Wankai New Materials runs its own laboratory accredited to ISO/IEC 17025.

What is usually tested in PET resin

The set of parameters depends on the grade and its application. For bottle-grade PET the industry typically checks:

• intrinsic viscosity (IV), which governs processing and the strength of the finished article;
• colour values, which affect bottle clarity and tint;
• acetaldehyde content, which matters for the taste of water and beverages;
• moisture, melting point, pellet size and uniformity, and dust content.

The exact list of parameters and test methods for each grade is given in its TDS and in the certificate of analysis (CoA) for each lot.

Quality starts in production

The laboratory confirms quality, but consistency is built into the process itself. At the plant, melt polycondensation runs on China Kunlun technology, solid-state polycondensation on BÜHLER equipment (Switzerland), and production is centrally controlled by a Honeywell DCS. Centralised control helps keep process parameters stable.

Which documents the buyer receives

Every shipment comes with a quality certificate, a CoA, specifications and a certificate of origin. Copies of the FDA and EU food-contact certificates are available on request. We prepare the contract and documents in Russian.

A tip for incoming inspection: compare the CoA data with your own test results and keep a retained sample from each lot — this makes it much easier to resolve any quality question.

Request the TDS and a sample of the grade you need, or copies of the plant's certificates.