Announcing a new technology platform exclusively from Amcor Rigid Plastics

Compression Blow Forming A White Paper

Specifi cally, for the production of rigid high-density polyethylene (HDPE) pharmaceutical containers (over-

the-counter and prescription type), a new process called Compression Blow Forming (CBF) has recently taken

center stage as a highly viable alternative to IBM, providing a broad range of benefi ts including less material

waste, shorter cycle times, improved quality, and the potential for lightweighting. Amcor Rigid Plastics, the

world’s leading producer of rigid plastic packaging, has commercialized the industry’s fi rst compression

blow forming (CBF) machine. The breakthrough process, which combines compression molding and blow

molding, was originally developed by Sacmi Imola, S.C., the industry’s leading manufacturer of compression

molding equipment for closures. Amcor collaborated with Sacmi in a 14-month development project to adapt

the unique technology for pharmaceutical packaging. The two companies primarily focused on machine

effi ciencies and implementation of process control enhancements to ensure the new technology platform met

the demanding requirements of pharmaceutical manufacturers.

Delivers Major Benefits for Pharmaceutical Packaging

Over the past several decades, plastic bottle manufacturers have relied on standard Injection Blow Molding (IBM) technology as the preferred process choice for the production of rigid containers for the pharmaceutical industry. The process has served the industry well in terms of meeting medium- to high-volume production requirements and off ering scrap-free manufacturing with no trimming, an injected neck fi nish, and no particulate. However, drawbacks in the areas of quality, process control, cycle time, and sustainability have always limited the process and new alternative manufacturing technology has been slow to emerge over the years.

Newly Commercialized Compression Blow Forming (CBF) Process

www.amcor.com

Pellet InputContainer Output

www.amcor.com

Continuous Rotary System Offers Process Efficiencies Compression blow forming is a continuous rotary process whereby the material is extruded, cut, and

precisely transferred into the preform cavity. A preform is formed and a pre-blow and full-blow process is

completed in the same mold station with no transfer of the parison. In the CBF continuous rotary process,

the plastic preform undergoes compression forming through the use of a neck ring, core, and compression

cavity. The neck ring carries the plastic preform through the continuous rotary motion with the entire mold

assembly (compression and blow), moving in synchronization in a circular 360-degree process. The machine

controls provide process sequencing, enabling plastic shot insertion, compression in the preform, pre-blow

of the preform, fi nal blow to form the container, and ejection of the completed container.

Compression blow forming’s continuous rotary motion eliminates station-to-station indexing time, thus

removing idle time in the process. The mold assemblies (compression and blow molds) are synchronized by

servo motors with a plastic shot transfer arm assembly. Thus, the stop-and-start 120-degree reciprocating

transfer motion common in IBM technology is eliminated.

Con

tinu

ous

Rot

ary

Syst

em

As each uniform HDPE resin shot is extruded, the CBF machine arm rotates across, taking each resin shot to its compression cavity.

The CBF machine compression forms a preform within the cup.

Manifold-Free System Results in Better Quality Perhaps one of the most signifi cant advantages of CBF is the elimination of the manifold hot runner system. The CBF process has no manifold after the extruder distributes the plastic to multiple cavities. This results in better quality parts because there are no temperature diff erences and less chance of resin burn and degradation. The resin does not remain at an elevated temperature before being compressed into a preform. Similarly, by avoiding channels of travel there is no accumulation of resin in dead corners of the manifold that typically leads to resin burn and contamination. With less particulate contamination, color and resin changes are quicker.

Another key feature of CBF is the pre-blow process which allows for eff ective separation of plastic from the compression core. The CBF process’ rotary motion and control actuation allows the blow process to start within a fraction of a second of compressing the preform. This reduces the chance of material sticking to the metal core rod, resulting in a more consistent and uniform wall thickness distribution and reducing the chance for fl ash. Without a manifold and with the lower heat requirements for compression molding, the plastic resists burning, resulting in lower black spec contamination in the container.

The CBF process also has an enclosed secondary conveyor system with post cooling which substantially reduces the dust /particulate exposure to the container.

www.amcor.com

Each bottle is pre-blown before the blow mold cavity closes over the preform.

The mold cavity closes and the bottle is blown.

Man

ifol

d-Fr

ee S

yste

m

www.amcor.com

More Accurate Weight Distribution is Achieved In compression blow forming, the extruded shot of plastic is transferred straight into the compression mold. This is achieved with a precision knife cut of the plastic over the barrel nozzle and a vacuum transfer into each compression cavity. An important feature here is that the shot weight is controlled for all cavities at one source point with a servo-controlled melt pump, resulting in much more accurate weight distribution across all bottle cavities.

The CBF process also operates at lower temperatures (30 degrees F cooler) which results in lower residual stress in the end product and improved cycle times The reduced heat input with compression molding means less heat to remove after blowing. In addition, the continuous rotary motion of the machine and secondary cooling after takeout on the conveyor also help to reduce cycle time.

Mor

e A

ccur

ate

Wei

ght

Dis

trib

utio

n

www.amcor.com

Fully Integrated Inline Inspection Ensures High-Quality Bottles Unique to the CBF process is a highly sophisticated inline quality inspection system which is fully inte-grated into the machine control. An infrared vision system detects dimensional variations for fi nish and body, and contamination (including any embedded opaque or metal particles). Meanwhile, an optional, fully integrated plasma surface treatment system is available for full wrap label and fi nish induction seal applications. Leak testing validated to 0.3 mm minimum hole diameter is performed immediately after the bottle is blown.

Key sustainability advantages include a signifi cant energy reduction through lower process tempera-tures and application of updated machine process improvements

Amcor has an exclusive arrangement with Sacmi to utilize the technology for pharmaceutical packaging applications in key regions. The company has already purchased a 12-cavity unit ( CBF-12), and is produc-ing 40 to 300 ml monolayer HDPE packer (over-the-counter and prescription) bottles at its Youngsville, N.C., facility.

The company sees a range of applicability for CBF and will selectively invest with customers in high-volume, long-term projects. In addition to the 12-cavity unit already in production, Amcor has committed to additional CBF systems. New-generation equipment will have the capability of producing HDPE, PP, and PET pharmaceutical containers.

Leak Detection Infrared Surface Examination Plasma Surface Treatment

Full

y In

tegr

ated

Inlin

e In

spec

tion