# Injection Stretch Blow Molding (ISBM) Chiller Profiling: Gate Freeze-Off Time, Delta T Uniformity, and Cycle Time
TL;DR — An ISBM bottle is blown from a preform whose finish was injection-molded at the top of the same blank, and every downstream variable — wall distribution, ovality, cycle pacing — answers to heat: where the preform carries it, how evenly the mold takes it away, and when the gate lets the cavity go. Injection molding and blow molding are recorded manufacturing processes, and PET and PETG are recorded materials, but ISBM process attributes are not recorded; chiller profiling is a project configuration. Gate freeze-off time, delta T uniformity and cycle time are subject terms with no published values — the airless bottle family's 89 catalog models and 5 ml to 120 ml capacities anchor the format, not the thermal window.
Why: Heat Is the Real Process Variable
- The bottle answers to thermal history. Injection stretch blow molding builds the finish on an injection-molded preform that later stretch-blows into its body — one blank carries both forming steps, and where heat sits in it at each moment decides how the wall distributes.
- Chiller profiling is how that history is kept stable. Mold steel temperature, coolant flow, and the moment the gate freezes all shape the part; none of it is recorded as data.
- The variant is a project decision. ISBM process attributes are not recorded; chiller profiling is a project configuration.
- The format window is recorded. The airless bottle family records 89 catalog models, capacities 5 ml to 120 ml.
- Processes and materials are mapped. Injection molding and blow molding are recorded processes, with assembly, mold tooling development and the decoration register alongside; PET and PETG are recorded materials.
How: One Blank, Two Forming Steps, One Thermal Map
1. The preform path: the finish rides the blank
Injection molding first: the preform — a test-tube shape capped by a finished neck with its threads — is molded in one stroke. The finish is created by steel rather than air, and the gate that fed it sits at the base of the preform. The blank is then conditioned for the blow step: reheated until the material is pliable enough to stretch, pushed by a stretch rod, and inflated against the blow mold while the neck remains the same part. Injection molding and blow molding are the recorded processes in this story, with assembly, mold tooling development and the recorded decoration processes around them; the stretch-blown body is the blowing side of the family, entered through the variant the project selects.
2. Why chiller profiling exists
Where the steel is warm or cool relative to its neighbors shows up as a wall that thins or a band that refuses to fill out. Chiller profiling maps coolant temperature and flow zone by zone — cavity to cavity, core to neck ring — so the steel removes heat at the same rate everywhere the wall wants it. The stakes concentrate at two places.
First, gate freeze-off: the moment the base gate solidifies enough to hold pressure defines when packing stops and when the cavity can release. A gate that freezes inconsistently walks straight into short-fill or flash anomalies at the same cavity position run after run. Second, the finish: the neck ring sees the most concentrated steel, and delta T between halves of the neck ring is the classic seed of ovality at a finish that must later pair with a closure. None of this is published; it is the thermal under-story of any project that runs this route.
3. Gate freeze-off, delta T, cycle time: three meters, one mechanism
Gate freeze-off time is the clock from the end of injection to the moment the gate seals; delta T uniformity is the spatial steadiness of that clock across the mold and its cavities; cycle time is what the slowest element of the chain forces on the pace. The three interact: cooling water a fraction warmer at one inlet feeds steel that crystallizes later in one region, which either costs cycle time waiting for the coldest control point or risks dimensional drift. The working posture is to treat the three as one coupled system, with the mold temperature map as the fixed reference.
There are no published values for any of them — all are configured and confirmed per project. The gate-freeze logic appears elsewhere in the plant: an injection-molded closure survives on the same gate-size and pack-pressure interplay, but the preform geometry and the stretch that follows shift the numbers, so no value transfers between projects as a default.
4. What the record actually holds
The catalog's fixed points are four. Manufacturing: blow molding and injection molding are recorded processes, with assembly, mold tooling development and the recorded decoration processes alongside. Materials: PET and PETG are recorded. Product: the airless bottle family records 89 catalog models with capacities from 5 ml to 120 ml. Position: ISBM is the industry-shared name of a process variant, but ISBM process attributes are not recorded; chiller profiling is a project configuration.
The variant sentence carries the whole discipline: compression blow forming, injection stretch blow molding, or another route in the family — is a project decision, not a catalog field. Whatever the route, the capability behind it is the recorded part; the thermal chain is negotiated per project.
5. Where verification lands
Release for a chiller-profiled bottle is earned on the part, not on the plan: wall distribution across the measured body, ovality at the finish that must pair with a closure, corner fill, and the pack-level checks the program records. The bottle family's laboratory coverage sits under the 12-test matrix, and the leakage and dimensional hooks live under the program's quality control checks. Every criterion is applied to the project's own cavity set and resin batch; nothing is inherited as a default.
<pre class="language-mermaid"><code>flowchart LR
A[Recorded capability<br/>injection molding] –> B[Preform with finish<br/>injection-molded]
B –> C[Reheat<br/>profile set per project]
C –> D[Stretch blow<br/>recorded blow molding capability]
D –> E{Chiller profiling<br/>project configuration}
E –> F[Gate freeze-off time<br/>no published values]
E –> G[Delta T uniformity<br/>no published values]
E –> H[Cycle time<br/>no published values]
F –> I[Airless bottle family<br/>89 models · 5 ml–120 ml]
G –> I
H –> I
I –> J[Program checks<br/>12-test matrix · quality control]
</code></pre>
What: Recorded Program Data and Verification Hooks
- Manufacturing processes — injection molding and blow molding are recorded, with assembly, mold tooling development and the recorded decoration processes alongside. ISBM process attributes are not recorded; chiller profiling is a project configuration.
- Materials — PET and PETG are recorded materials.
- Product landscape — the airless bottle family records 89 catalog models, and capacities from 5 ml to 120 ml are established in the record.
- Verification hooks — laboratory coverage for the bottle family sits under the 12-test matrix; program-level testing hooks are documented under quality control.
- Boundary — gate freeze-off time, delta T uniformity, cycle time, chiller set points and preform reheat profiles are not published by the program; they are configured and confirmed per project. Whether a project runs compression blow forming, injection stretch blow molding, or another route in the family is a project decision, not a catalog field.
Gotchas
- ISBM is not an attribute. ISBM process attributes are not recorded; chiller profiling is a project configuration — never present set points, timing or profiles as program data.
- Zero published thermal values. Gate freeze-off time, delta T uniformity and cycle time are subject terms; no number for any of them exists in the record to quote.
- The route is a decision, not a field. Compression blow forming, injection stretch blow molding, or another route in the family — is a project decision, not a catalog field.
- The 89-model count is a format window. The airless bottle family's 89 catalog models and 5 ml to 120 ml capacities describe the formats served, not wall, ovality or cooling expectations.
- Gate freeze-off logic travels; numbers do not. The mechanism transfers from closure molding to preform molding, but the values do not — preform geometry and the stretch step change everything.
- Chiller adjustments trade against each other. Cooling harder shortens cycle time and risks dimensional drift; cooling softer protects dimensions and stretches the cycle — an optimization with no published optimum.
Related Resources
- Categories: Bottles
- Related insights: Compression Blow Forming vs. ISBM · Bio-PET vs Virgin PET: IV and Acetaldehyde · Liquid Foundation Priming Failure · The 12-Test Lab Matrix
- Quality Control — program-level checks that apply to blown bottles