ISBM materials / Material evaluation
PET Injection Stretch Blow Molding
PET injection stretch blow molding should be assessed against a named resin grade, a defined bottle and the proposed one-stage process. Intrinsic viscosity, drying history and preform geometry belong in the same review. A PET label alone cannot establish clarity, wall distribution or production output. Use the evaluation record below to connect incoming material evidence with trial samples, then confirm the machine and mold configuration for the accepted bottle rather than selecting equipment from resin name alone.
Which PET grade fits the intended bottle?
Specify the supplier, full grade designation, manufacturing source and intended end use before comparing data sheets. Indorama publishes different PET grades for different applications, including general containers, carbonated drinks and hot-fill packaging. These are distinct material offerings, not evidence that one grade satisfies every bottle requirement. Review the resin manufacturer's PET portfolio.
Treat intrinsic viscosity (IV) as a material characterization value, not a machine setting. Keep the reported method and units with each result. An incoming certificate describes the delivered batch; a preform or bottle test describes material after processing. Comparing equivalent measurements can help investigate a change during drying or molding. PTI describes this distinction in its preform and bottle testing methods.
What must the material review contain?
Drying evidence
Use the current instructions for the actual resin grade. Record dryer conditions, residence time, material throughput and the measured moisture result at a defined sampling point. A temperature setting alone is not proof that the material was adequately dried.
Clarity and crystallization
Define acceptable haze, color and visible defects on the actual container. Check the preform and bottle separately. If crystallinity is being investigated, agree the test method and sample location; appearance alone cannot identify its cause.
Bottle and preform geometry
Provide bottle volume, weight, neck finish, height and body dimensions together with the proposed preform. Identify shoulder and base regions where material distribution must be assessed. Do not apply a universal stretch ratio to all designs.
Batch traceability
Retain grade, lot, additive or colorant details and storage history. Mark trial samples with the material lot and process revision so that a passing sample can be traced to the conditions that produced it.
How should a PET trial be evaluated?
Agree the bottle drawing and acceptance criteria before the trial. Start with the supplier-approved material preparation and an engineering-approved machine and mold configuration. Record the actual process conditions and retain representative samples rather than judging the trial from one attractive bottle.
Measure dimensions at agreed locations, examine the neck and sealing surface, and map wall distribution where the design requires it. Define the application-specific tests separately: a cosmetic container, a pressure-bearing package and a hot-fill container do not share one universal acceptance plan. Keep material-property results separate from finished-package performance.
For a one-stage process, document how the preform reaches its stretch-blowing condition within the selected station sequence. If the proposed grade or geometry changes, review the trial scope again. A previous trial on another grade is supporting context, not automatic approval.
PET evaluation record
| Review item | Record to collect | Decision or acceptance basis |
|---|---|---|
| Resin identity | Supplier, grade, lot and data-sheet revision | Material matches the trial authorization |
| IV comparison | Incoming and molded-sample results, units and method | Comparison uses equivalent methods and agreed limits |
| Preparation | Drying instructions, run log and moisture result | Preparation meets the grade-specific requirements |
| Optical assessment | Haze/color method, specimen location and reference sample | Actual bottle meets the approved visual standard |
| Bottle distribution | Drawing revision, section weights or thickness locations | Results meet the bottle-specific requirements |
| Trial disposition | Sample IDs, configuration and responsible reviewer | Approved, further development or unsuitable for this proposal |
This is a record structure for a real project, not a completed test certificate. Populate it with measured results and the review decision; do not convert untested assumptions into acceptance values.
Where does material evaluation end?
This page addresses PET grade and bottle feasibility. Equipment procurement is a separate decision: the PET bottle making machine page addresses that scope. The broader injection stretch blow molding machine overview introduces the process equipment.
A resin data sheet is not a declaration that the finished container meets every food-contact, chemical-resistance or heat-exposure requirement. Obtain the documents applicable to the grade and intended market, then evaluate the finished package under its actual use conditions. No specific grade-machine-bottle combination is approved by this guide.
Questions before the next step
What should I send with an IV value?
Include the resin grade and lot, test method, units, sample type and any additive information. A number without this context cannot establish whether the incoming resin and molded sample are comparable.
How do I verify drying rather than just record a setting?
Use the resin supplier's instructions and retain the operating log plus a moisture measurement from an agreed sampling point. Document the method and the time between sampling, transfer and processing.
When is a new engineering review needed?
Review a changed resin grade, color system, preform, bottle geometry or process configuration before treating earlier results as applicable. Resolve material feasibility before committing to a production specification.
Technical references
Supplier information is grade-specific. Review the current documents for your proposed material; these references do not certify an ISBM machine or a finished bottle. Reference review date: November 9, 2026.
Discuss Your Bottle Project
Share the exact resin grade, bottle drawing or sample, capacity, weight, neck dimensions, bottle height and body diameter. Include required accepted output and your factory location and power supply.
Provide the material documents and available trial records so the proposed ISBM configuration can be reviewed against your actual requirements.