How IBM Works:
3-Station Injection Blow Molding Process

MOULD CLOSE + CORE ROD ENTRY · 0.2–0.4 s

The injection mould closes around the core rods as the turret indexes to Station 1. The injection mould’s two halves (A-side and B-side) clamp shut with the full ZQ machine clamping force applied — 400 KN on ZQ40 to 1,350 KN on ZQ135. The core rod is now centred within the closed injection mould cavity, with the annular space between the cavity wall and the core rod surface defining the preform tube geometry, and the neck insert at the top of the cavity surrounding the core rod’s neck zone to form the thread and other features.

INJECTION FILL · 0.8–2.0 s

The plasticising screw advances, injecting the metered HDPE shot through the hot runner manifold into all cavities simultaneously. The hot runner maintains the HDPE at melt temperature (195–225°C) through the manifold to the gate at the base of each core rod’s tip — ensuring all cavities fill at the same time and temperature regardless of their position in the mould. Injection pressure: 90–150 MPa, with fill time 0.8–2.0 s depending on preform size and HDPE viscosity (MI).

HOLD + COOLING · 0.4–1.0 s + 0.5–1.5 s

After fill, the screw holds pressure (50–75% of peak injection pressure) to compensate for HDPE volumetric shrinkage as the preform solidifies. Cooling water circuits in the injection mould (set at 12–20°C for pharmaceutical, 18–28°C for household/personal care) rapidly solidify the preform from the cavity wall inward. The preform solidifies on the core rod — the core rod surface defines the preform’s inner bore diameter and surface finish. Cooling must solidify the preform sufficiently to maintain dimensional stability when the mould opens, but not so completely that the preform loses the residual heat needed for blow inflation at Station 2.

MOULD OPEN + TURRET ROTATION · 0.3–0.5 s

The injection mould opens while the preform remains on the core rod — held by the shrink grip of the HDPE onto the core rod surface. The turret rotates 120° to carry the preforms to Station 2. At the same time, a new set of empty core rods enters Station 1 for the next injection cycle. The preform must retain sufficient heat (typically 90–130°C at the body wall surface when it enters the blow mould) to allow inflation without cracking — too cold and the preform body resists blowing; too hot and the neck zone that was precisely injection-moulded at Station 1 can distort during turret transit.

Blow Pressure

0.5–0.95 MPa

Must overcome HDPE melt resistance to inflate preform; too low → incomplete body inflation; too high → localised wall thinning at high blow-ratio zones

Blow Dwell

0.9–2.0 s

Contact time with blow mould wall for cooling. Too short → container base deformation after ejection; adequate dwell ensures dimensional stability at Station 3

Mould Temperature

14–30°C

Cooling water temperature at blow mould. Lower → faster solidification (shorter dwell possible); higher → slower solidification but better surface replication (cosmetic containers)

Preform Temp.

90–130°C

Body wall surface temperature entering blow station. Optimum: above HDPE glass transition and below melt temperature — hot enough to blow freely, cool enough to hold shape after inflation

FUNCTION 01

FUNCTION 02

FUNCTION 03

FUNCTION 04

Preform bore mandrel

Neck geometry carrier

Blow air conduit

Neck geometry isolator

During injection, the core rod is inside the injection mould cavity, defining the preform’s interior bore diameter and surface finish. The core rod surface becomes the preform interior — any scratch or wear on the core rod surface reproduces in every container that core rod produces.

The preform is carried from Station 1 to Station 2 on the core rod — the core rod holds the preform by residual thermal shrink grip. The neck features (thread, bead, sealing land) formed in injection remain undisturbed during transfer because they are held against the core rod surface.

The core rod has a hollow internal bore (typically 2–5 mm diameter) running its full length, connected to the machine’s compressed air supply. Blow air exits at the core rod tip, entering the preform interior and inflating the body against the blow mould cavity wall.

During blowing, the core rod body occupies the neck bore — physically preventing blow air pressure from contacting or deforming the neck zone. The neck dimensions remain exactly as injection-moulded throughout the blow phase. This structural isolation is why IBM neck OD stays at ±0.05 mm through the complete process.

10 ml HDPE Pharma (20 cav, ZQ80) — 4.0 s

300 ml HDPE Shampoo (6 cav, ZQ110) — 5.0 s

Structural basis, not process control

IBM: The preform is formed by injecting HDPE into a closed mould around a core rod — no excess material, no pinch point, no trim. The container base is formed by the core rod tip during injection (the base is the solid end of the preform tube). There is no base parting line because the preform base was never a mould split — it was the core rod tip zone. Result: zero flash, zero trim operation, no flash contamination risk.

EBM: An extruded parison (an open-ended tube) is pinched closed at its bottom end by the blow mould closing, creating a base pinch weld and excess material (flash) that must be trimmed. The pinch weld is structurally weaker than the container body wall and the trim flash must be removed in a secondary operation. These are inherent consequences of the EBM parison-pinch architecture — they cannot be eliminated by process optimisation.

Physical isolation, not dimensional control

IBM: The neck is formed in the injection mould’s neck insert (±0.01 mm CNC tolerance) during Station 1. Throughout Station 2 (blow), the core rod physically occupies the neck bore — blow pressure is mechanically isolated from the neck zone. The neck OD when stripped at Station 3 is the same as the neck OD as-injected at Station 1: ±0.05 mm. No process in Stations 2 or 3 can change the neck dimension because no process force reaches the neck zone.

EBM: The EBM neck is formed by blow air pressure acting on a hot parison tube from inside — the blow pressure simultaneously shapes the body and the neck, with no mechanical constraint separating them. Blow pressure variability (0.5–2.0 MPa cycle-to-cycle variation) directly translates to neck OD variability of ±0.15–0.25 mm. This inherent coupling between blow pressure and neck geometry cannot be broken in EBM without secondary neck finishing operations.

Q 01

Why does IBM use a rotating turret rather than a linear transfer system between stations?

The rotating turret is IBM’s defining mechanical architecture choice — and it is the reason IBM machines are compact, mechanically simple and dimensionally consistent. The turret carries all three sets of core rods in a single rigid plate, rotating 120° between stations with all core rods moving exactly the same angular distance simultaneously. This means all core rods are simultaneously at all three stations at all times — no core rod is idle or in transit. By contrast, a linear transfer system would require core rods to queue, transfer and wait, introducing: additional machine length (2–3× footprint versus turret IBM); transfer mechanism wear points that introduce positional variation; and idle time during which core rods cool between stations, requiring reheating conditioning zones. The turret architecture also means that every core rod in the machine follows exactly the same angular path with the same rotation timing — a geometric consistency that contributes to IBM’s cavity-to-cavity uniformity. The turret’s single central rotation axis also allows the injection unit, blow station and stripping station to be permanently oriented relative to each other at fixed 120° angles, eliminating the need for adjustable alignment mechanisms that would introduce positional drift over production life.

Q 02

What causes IBM container surface defects — and which station produces each type?

IBM container surface defects are station-specific, which allows systematic root cause identification during production troubleshooting. Station 1 defects (on the preform / container neck zone): sink marks at the neck wall junction → insufficient hold pressure or hold time; silver streaks at the neck gate → HDPE moisture above 0.02% (pre-drying required); short shot at the neck thread → gate or hot runner blockage; flash at the neck OD parting line → injection mould wear at the neck insert parting line (requires neck insert replacement or lapping). Station 2 defects (on the container body): whitening / haze lines on the body wall → preform temperature too low at blow entry (Station 1 cooling too fast — reduce cooling time or increase cooling water temperature); incomplete body inflation → blow pressure too low or preform temperature too cold; body wall thinning at shoulder → preform wall distribution insufficient at shoulder zone (preform design change needed); blow mould surface marks → blow mould cavity damage (inspect blow mould and polish if scratched). Station 3 defects (container base / shoulder zone): shoulder deformation → stripping force too high or container too hot at stripping (extend blow dwell or lower blow mould temperature); base drag marks → core rod tip scratch (inspect and polish or replace core rod); base haze / crystallisation marks → container too cold at stripping (reduce blow dwell slightly). The station-specific nature of IBM defects is a significant troubleshooting advantage — a defect located precisely on the neck points to Station 1, a defect on the body points to Station 2, and a defect on the base or shoulder points to Station 3, immediately narrowing the root cause investigation scope.

Q 03

How does changing mould temperature affect the IBM container quality vs cycle time trade-off?

Mould temperature in IBM is a critical process variable that creates a direct quality-versus-cycle-time trade-off, and understanding this trade-off is essential for IBM production optimisation. Injection mould temperature (Station 1): lower temperature (12–18°C) → faster preform solidification → shorter Station 1 cooling time → potentially shorter cycle time. But too-low injection mould temperature produces: insufficient preform surface replication (reducing gloss in cosmetic applications), higher residual stress in the preform neck zone (potentially reducing neck OD dimensional stability under fill forces), and inadequate transfer temperature at Station 2 entry (preform too cold for clean inflation). Optimal injection mould temperature is therefore a balance between cooling speed and preform quality — pharmaceutical IBM typically uses 14–18°C, cosmetic ABS IBM uses 55–70°C (prioritising surface quality over cycle speed). Blow mould temperature (Station 2): lower blow mould temperature → faster container body solidification → shorter blow dwell required → shorter cycle time. But too-low blow mould temperature produces: surface whitening on the container body (HDPE crystallises too rapidly, producing visible spherulites on the surface); poor surface texture replication (embossed details are less sharp at cold mould temperatures because the HDPE surface solidifies before fully contacting the mould cavity wall); and base deformation at stripping (container is too stiff and brittle when stripped too cold, producing micro-cracks at the base corner zone). For each application (pharmaceutical, food, personal care, cosmetic) and each HDPE grade, Korea Ever-Power establishes the optimal mould temperature range during the pre-delivery production trial — the range that minimises cycle time while maintaining all container quality specifications — and records this as the qualified process parameter range in the production trial report.

Q 04

What is the IBM preform, and how does its design determine the finished container wall distribution?

The IBM preform is a thick-walled hollow tube produced at Station 1 — it has the container’s finished neck (thread, features, sealing land) already formed at its top end, and an unconstrained body tube below the neck that will be inflated at Station 2 to become the container body. The preform design — specifically its body wall thickness as a function of axial position from neck to base — determines how the HDPE material distributes into the finished container body during blow inflation. This is the fundamental IBM wall engineering parameter. In a cylindrical container, a uniform-wall preform (same wall thickness from shoulder to base) produces a container body wall that is approximately uniform from shoulder to base — the blow ratio (body diameter ÷ preform OD) is constant along the container height, so the HDPE stretches the same amount at every axial position. In a non-cylindrical container — oval cross-section, waisted body, wide shoulder with narrow base, or shampoo oval — the blow ratio varies with axial position. The shoulder zone (where the body transitions from the narrow neck diameter to the maximum body diameter) has the highest blow ratio and therefore the highest wall thinning risk. Korea Ever-Power engineers the preform wall thickness profile for each IBM container design using blow ratio calculation: at each axial position, preform wall thickness × preform circumference = finished container wall thickness × finished container circumference (conservation of mass). Where the finished container circumference is largest relative to the preform circumference, the preform wall at that zone must be thickest to compensate — this is the shoulder-zone wall bias used in shampoo and condiment IBM preform design. The preform wall profile is CNC-machined into the injection mould core cavity to ±0.02 mm accuracy, producing the specified wall distribution in the finished IBM container.

Q 05

Can IBM produce containers with handles, and what are the design constraints?

IBM cannot produce hollow integral handles — the blow mould architecture that eliminates flash (no pinch weld) also eliminates the ability to form a hollow loop handle because hollow handle formation in blow molding requires a parison to be pinched and welded across the handle opening during blow mould closure. Since IBM has no parison pinch, it has no handle pinch — integral hollow handles are EBM’s exclusive capability. IBM containers can, however, incorporate several forms of non-hollow handle features: (1) solid grip zones — the IBM blow mould can incorporate ergonomic grip recesses (indentations) on the container body sides; the HDPE body inflates into these recesses, creating grip features that function like handles for hand-holding the bottle during dispensing, without being hollow through-handles; (2) solid textured grip zones — circumferential ribs, dimples or diamond-knurl patterns on the IBM blow mould cavity transfer to the container body surface, providing grip without changing the body’s cross-sectional profile; (3) external handle clips — a separate injection-moulded handle component clips onto the IBM bottle’s neck or body features post-production, commonly used on Korean large-format (500 ml+) household chemical IBM containers. For Korean applications requiring true through-handles (gallon-size Korean laundry detergent, Korean bleach large format), EBM is the correct process — IBM’s handle limitation is structural to its process architecture and cannot be overcome by tooling or parameter changes.

Q 06

What is the maximum container volume IBM can produce and what limits it?

The practical maximum IBM container volume on Korea Ever-Power’s ZQ135 (1,350 KN) is approximately 1,000–1,500 ml at 1–2 cavities for non-pharmaceutical applications, and approximately 500 ml at 4 cavities for pharmaceutical applications. The theoretical IBM volume limit is set by the intersection of three constraints that all tighten as volume increases: clamping force, platen size and shot weight. As container volume increases, the preform body becomes longer and wider — increasing both the per-cavity injection clamping force requirement (proportional to projected area × injection pressure) and the per-cavity platen footprint (proportional to body cross-sectional area). Shot weight constraint: a 1,000 ml HDPE IBM container at 1.0 mm average wall weight is approximately 55–65 g per container — a 2-cavity 1,000 ml mould on ZQ135 requires a shot weight of 110–130 g per cycle, which approaches the ZQ135’s shot weight limit and leaves no margin for mould and hot runner system hold-up. In practice, Korean IBM applications above 500 ml are uncommon because: (1) Korean food and personal care brands at 500 ml+ typically specify EBM (with handles, for large format detergent and rinse containers where handled bottles are preferred); (2) Korean pharmaceutical containers are almost never above 250 ml in IBM; (3) Korean cosmetic IBM is not specified above 500 ml. The commercial IBM volume optimum — the volume range where IBM’s quality advantages over EBM are most valuable and its production economics are most competitive — is 10–500 ml, which is the primary ZQ series design target range.