Blow Molding Options

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Blow molding is not just blow molding. There are many different technologies under the blow mold name, and each has a specific market segment. Here is a summary of the main types and markets they cover.

1. Extrusion Blow Mold - Shuttle or Linear(Continuous Extrusion)

These are classic EBM formats with continuous extrusion systems, and are the most popular. End products are personal care, chemicals, household products, oil bottles and industrial containers. Range is generally 1oz up to 50 gallon (oversize). Most modern machines are linear carriage with bobbing head, but shuttle (angled carriage) are still sold.

EBM Machine
EBM Machine

2. Accumulator Head

These are single shot, as opposed to continuous extrusion, industrial part machines, but they are also used for larger, low volume usage containers. Typical usages are large tanks, sea floats, car components, industrial components. Platens are normally fixed, with robot arm takeout. Sizes up to 3000 litres are made, and platens are sometimes up to 4 metres (13 feet) in height for large units.

Accumulator Head Machine
Accumulator Machine

3. Injection Blow Mold (or IBM)

IBM is used where a combination of injection molded neck (for high precision) and a blow mold are used in tandem. The result is an extremely accurate bottle not obtainable in EBM. Typical markets are pharmaceuticals, personal care precision containers (deodorant stick) and industrial (often medical) parts. Large cavitation (of up to 32 cavities) gives very high output, and there is no de-flash scrap - making IBM an excellent investment choice for small containers.

IBM Machine
IBM Machine

4. Reciprocating Head (Recip) machines

This category of machines is used normally for high output thin walled containers such as milk bottles, and is widespread in that industry. The machines have been adapted for above 1 gallon and similar containers. Great advances have been made to adapt the technology, but continuous extrusion machines are more accurate and much more widespread.

Reciprocating Head machines

5. Injection Stretch Blow Machinery (PET) (ISBM)

This equipment is used almost exclusively for PET (transparent) containers, although some PP (polypropylene) and newly developed PET - type resins are being used. The machines are 1 step, inject the preform, stretch the plastic for strength, then blow the final container. Difficult shapes of PET are more easily achieved than 2 step (blow molding a finished preform previously injected). The downside is very high cost molds, and slow production machinery.

ISBM Machine
ISBM Machine

6. Reheat Stretch Blow Machinery

This equipment is very widespread for PET 'standard' containers. Preforms are purchased ready to use, and fit into the machine, and reheated and blown. Almost all beverage, sports drinks and the like use this process. Speeds are very high, with rotary machinery in multi cavity reaching 50,000 parts / hour and more. In line RHSB machines are very popular for shorter runs and ease of use.

Reheat Stretch Blow Machine
Reheat Stretch Blow Machine

7. Wheel Technology (PET and PP)

Wheels are very prevalent in USA because of their high output on items such as oil bottles. Wheels can be horizontal or vertical in construction and are high in cavitation. For repetitive, low changeover, volume products they are very competitive, but lack the versatility of in-line equipment. Often poor in neck finish and difficult to put into downstream equipment, plus the long, costly changeover time, have put wheels at a disadvantage to high-speed linear EBM systems in many situations.

Typical PET / PP Wheel
Typical PET / PP Wheel

There are a number of hybrid intermixes of these 7 technologies, but these form the basis of 95% of blow molding process.