In the manufacturing of cosmetic packaging, Extrusion Blow Molding (EBM), Injection Blow Molding (IBM), and Injection Stretch Blow Molding (ISBM) are three core processes for creating hollow containers. This article provides product managers with a clear analysis of these processes and their typical applications to inform your selection process.

1. Extrusion Blow Molding (EBM)
Process Overview: This method involves extruding molten plastic into a hollow tube (parison), which is then captured in a mold and inflated with compressed air to take the shape of the mold cavity.
Key Characteristics:

• Cost: Low mold cost and low per-unit cost.

• Design Flexibility: Ideal for containers with irregular shapes, handles, or large capacities.

• Quality: May have pinch-off seams requiring trimming; lower neck finish precision.

• Efficiency & Volume: Fast cycle times, cost-effective only for high-volume production runs.
  Typical Applications: Large-volume containers for shower gel, shampoo, body lotion, and jars for creams.

2. Injection Blow Molding (IBM)
Process Overview: This two-step process first injection molds a preform with a precise neck finish onto a core rod. The preform is then transferred to a blow mold station where it is inflated and cooled into its final shape.
Key Characteristics:

• Cost: Higher tooling and equipment costs.

• Precision: Excellent neck finish accuracy with clear threads, no flash, and superior seal integrity.

• Quality: High-quality surface finish and good wall thickness control.

• Limitation: Primarily used for symmetrical, round, or oval containers.
  Typical Applications: High-end products requiring excellent sealing: serums, essential oils, perfume bottles, and small eye cream jars or sample bottles.

3. Injection Stretch Blow Molding (ISBM)
Process Overview: This process adds a stretching phase to IBM. The injection-molded preform is heated and then stretched longitudinally by a mechanical rod before being inflated with compressed air for radial stretching (biaxial orientation).
Key Characteristics:

• Cost: Highest equipment and tooling cost.

• Performance: Biaxial orientation significantly enhances mechanical strength, clarity, gas barrier properties, and dimensional stability.

• Aesthetics: Provides excellent gloss and crystal-clear transparency for a premium look.

• Lightweighting: Enables lightweight container design, saving material.
  Typical Applications: The ideal choice for PET transparent bottles for toners, essences, lotions, and also widely used for beverage bottles and pharmaceutical packaging.

Summary Comparison Table