Blow Molding machines are essential in manufacturing hollow plastic parts—such as bottles, containers, tanks, and more. The right choice of machine affects production efficiency, material use, product quality, and costs. Below are the main kinds of blow molding machines, with their processes, applications, advantages and disadvantages.

1. Extrusion Blow Molding (EBM)

Process: A continuous or intermittent extruder produces a molten plastic tube (called a parison). The parison is then enclosed in a mold and air pressure inflates it to take the mold shape. Depending on design, the extruder either runs continuously (continuous extrusion) or intermittently (parisons made one at a time or in cycles).

Applications:

• Large bottles, drums, jerry cans

• Big hollow parts (fuel tanks, industrial containers)

• Products that need handles or complex shapes that cannot be made by simple injection molding

Pros:

• Good for high volume production

• Flexible in product sizes and shapes

• Lower cost per part for larger items

Cons:

• Wall thickness may vary if parison control is not well done

• More material might be needed for structural integrity in some shapes

• Less precise finish compared to injection blow molding

2. Injection Blow Molding (IBM)

Process: This combines injection molding and blow molding. A preform is first made via injection, including the neck finish; then the preform is transferred to a blow mold, inflated into the final shape.

Applications:

• Small‐to‐medium containers requiring tight tolerances (e.g. pharmaceutical, cosmetic bottles)

• Products where the neck design or threaded finish is critical

Pros:

• High precision, good surface finish

• Consistent neck and thread features

• Less post‐processing needed for certain features

Cons:

• Higher equipment and tooling cost

• Slower cycle times for larger volumes compared to some extrusion blow machines

3. Stretch Blow Molding (SBM)

Process: Used primarily for materials such as PET. The preform is heated, then stretched both axially (lengthwise) and radially (outwards) before blowing. This enhances material properties (strength, clarity).

Applications:

• Beverage bottles (water, soft drinks)

• Food & dairy containers

• Personal care product bottles, where appearance (clarity) and strength matter

Pros:

• Lighter bottles for same strength (material savings)

• Excellent clarity and aesthetic finish

• Good mechanical properties (resistance to drop, pressure, etc.)

Cons:

• Requires more specialized machinery and controls

• Higher up-front cost; energy for heating/stretching; more constraints on shape/design

4. Co-extrusion / Multi-layer Blow Molding

Process: Multiple extruders feed different layers of plastic into a single parison. The layers may have different properties such as strength, barrier resistance, or color. Then, like in extrusion blow molding, parison is inflated into the mold.

Applications:

• Containers needing barrier layers (for gas, moisture)

• Fuel tanks, chemical containers where corrosion or permeation matters

• Food packaging that requires preserving freshness or preventing odor/carrier migration

Pros:

• Combines multiple material properties in one part

• Enhanced performance (barrier, strength, appearance)

• Flexibility in material combinations

Cons:

• More complex to manufacture and maintain

• Higher cost of raw materials and processing

• More complex tooling and layer control needed

5. Accumulator / Reciprocating blow molding machines

These are variants or subcategories of extrusion blow molding, distinguished by how the plastic is handled before blowing.

• Accumulator blow molding: Plastic melts are accumulated and then forced (shot) into the die to make the parison. Useful for heavy‐wall or large parts.

• Continuous vs intermittent extrusion: Continuous extrusion means constant flow and parison production; intermittent means on/off/fed in cycles.

• Reciprocating heads: The extruder or die moves back and forth to form parison; this can help with uniform wall thickness or for intermittent operations.

6. Rotary Wheel Blow Molding Machines

Process: In these machines, parisons are extruded and then captured by rotating “wheels” of molds (clamp stations), which move continuously or in indexed steps. Multiple molds may run in parallel.

Applications:

• Very high output production of bottles or containers

• When changeovers are less frequent and volume is large

• Products where consistency, tight tolerances, and high speed are necessary

Pros:

• Very high throughput (volume per day)

• Good consistency in weight and dimension

• Efficient for large production runs; cost per unit can be very low

Cons:

• Large capital investment

• Limited flexibility: changing product shape or size can require long downtimes or major tooling changes

How to Choose the Right Type

When selecting a blow molding machine, manufacturers typically consider:

• ✅ Product design & shape: Size, neck/thread, handles, wall thickness

• ✅ Material type: PET, HDPE, PP, PVC, barrier materials, etc.

• ✅ Production volume: High volume favors continuous / rotary machines; lower or niche volumes may justify injection or intermittent extrusion types

• ✅ Quality & appearance demands: Clarity, finish, tolerance

• ✅ Cost constraints: Equipment cost, mold/tooling, operating cost (energy, material waste)

• ✅ Flexibility: Ability to switch molds, sizes, shapes, or adjust production parameters

BOHANG’s Factory Strength in Blow Molding Machines

At BOHANG Machine, we combine deep technical expertise with strong manufacturing capability. Some points that show the factory’s strength:

• Experience and specialization in blow molding solutions: BOHANG provides specialized machines for bottle blowing and plastic container production. They understand different molding technologies and have tailored products accordingly.

• In-house production and engineering: BOHANG designs, builds and tests machines in its own facility, which allows better control of quality, faster turnaround on custom changes, and adherence to client specifications.

• Wide variety of products: The range from small bottles to larger containers, different materials, various shapes, showing flexibility in meeting different customer needs.

If you need machines for extrusion blow molding, stretch blow molding, or multi-layer blow molding, BOHANG can provide solutions with solid factory support, reliable technology, and good service.

Conclusion

Blow molding machines come in several major types—Extrusion, Injection, Stretch, Co-extrusion / multi-layer, Accumulator/reciprocating, Rotary —each with unique strengths and trade-offs. Matching the machine type to product requirements, production scale, quality demands, and cost constraints is crucial.

For companies looking for a strong partner, BOHANG offers factory capability, engineering know-how, and flexibility, making it a viable choice for many blow molding applications.