The Drum process
Virgin Plastic
Prime Grade, High Molecular Weight, High Density Polyethylene (HMWHDPE) is single sourced. Utilizing a proprietary gas phase technology natural gas, chemicals and heat are used to produce a high pure, food grade, virgin, natural, HMWHDPE pellet. These pellets are shipped to PolyCube in both rail cars and bulk trucks which are blown or vacuumed into our indoor, dedicated silo storage system.
Melt
The blended material is gravity fed into the extruder. The extruder is a long metal tube called a barrel with a large metal screw inside. The screw turns, driving the HMWHDPE forward between the narrow gap of the screw flights and the barrel wall. This causes frictional heat and the plastic melts.
Blow Mold
The Parison is then automatically cut from the head into the aluminum mold. The mold automatically closes while blow pins rise from the bottom. While air is blowing through the pins the mold is held tightly closed using hydraulic pressure. Next the Parison is blown into the walls of the mold. Chilled water is being pumped through small capillary tunnels inside the walls of the molds. This process transfers the heat from the plastic to the aluminum molds. The Drum is now formed.
Post Mold Cooling
The warm Drum is positively cooled in an additional 16 stations. In these stations the Drums are further cooled using ambient air flow to exchange the warm air with the ambient air in the drum. Since these Drums are open top this works very effectively. This process insures the Drum opening is round and the side walls and bottoms are flat.
Post Manufacturing Quality Control
A minimum of 2 Drums per shift are quality checked by a quality trained PolyCube Supervisor Inspector. They complete an extensive written check-list measuring for weight and wall thickness/distribution to insure the Drums are within preset tolerances.. The test sheets are reviewed and maintained by the Operations Manager. Other in house testing performed is a freezer drop. Lastly, official United Nations Department of Transportation testing is done annually to certify each design type by an independent third party DOT approved testing laboratory.
Blend
Prior to being vacuumed to the extruder, the HMWHDPE is air conveyed into a Blender / Mixer where precise amounts of colorant and production flash regrind are volumetrically mixed according to an exact computer controlled recipe.
Extrude
The melted plastic is driven into the Head of the Blow Molder from the extruder. Inside the head are proprietary mechanics and technology that, utilizing a computer generated recipe pre-set by our process engineers, squeezes and shapes the plastic into a tube called the Parison. This insures the exact and correct amounts of plastic are in the right parts of the Parison so when in the mold the Drum will have precise wall distribution.
De-flashing
Once the molding process is complete, the molds release their air and hydraulic pressure. The formed Drum is mechanically removed from the mold. The flash and excess plastic is precisely removed by an operator trained in this process. The flash is conveyed into a grinder for reprocessing.
Visual Inspection / Lidding / Inventory
Lastly there is a final Blow Mold Operator light inspection of the Drum for any visual defects such as carbon spots or open welds. If the operator determines the Drum meets the entire quality standard then he closes the drum with a metal locking ring and plastic cover.The drum is than transported into the general drum inventory ready for customer shipment. Any Drums failing the inspection process are cut and conveyed into the grinder for reprocessing.
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