Blow Molding Types and Terms

Blow Molded Plastics Types

  • Blow molded cases are formed by blow molding processes.
  • Blow molded plastics are plastic parts formed by blow molding.
  • Blow molders create hollow plastic parts.
  • Extrusion blow molding is the process in which a hot parison or preform is placed into a two-part mold. In the mold, the parison or preform is inflated with compressed air, which presses it against the walls, and then is cooled and removed by separating the mold halves.
  • Injection blow molding blends the two methods of blow molding and injection molding and is typically used in the manufacturing of soda bottles. A preform, which is similar to the parison, is either injection plastic molded and then transferred to a blow molding machine, or the injection and blow molders are combined.
  • Injection stretch blow molding (ISBM) is a two-stage, stretch blow molding process in which a preform is injection molded and then transferred to another station where it is blown and ejected from the machine.
  • Plastic blow molding is a process that uses inflated thermoplastics in molds.
  • Plastic bottles are hollow containers made of plastic.
  • Reheat and blow (RHB) is a stretch blow molding process in which a preform is injection molded by a vendor and then purchased and reheated by another company.

Blow Molded Plastics Terms

Clarity - The lack of haze or cloudiness in a plastic material.
 
Elastomer - A material that at room temperature has the ability to return to its original shape after being stretched up to twice its length.
 
Ethylene Vinyl Alcohol Copolymer (EVOH) - A high-barrier plastic resin packaging material.
 
Finish - Also known as the "E" dimension, it is the material enclosing the neck opening of containers that accommodate particular closures.
 
Flash - Extra plastic attached to a molding along the parting line. Flash must be removed (i.e. deflashed) before the part can be considered finished.
 
Flame Treating - A technique of making inert thermoplastic items responsive to adhesives, inks and paints. The submersion of the item in an open flame induces surface oxidation.
 
Fluorination - A procedure that diminishes permeability and increases the chemical resistance of different plastics and elastomers. The exposure of polymers to fluorine gas causes molecular structural surface changes.
 
Minimum Wall - The thinnest part of the wall of a bottle.
 
Mold Cavity - The hollow part of a group of molds that forms a container on bottle machines.
 
Mold Seam - A vertical line formed at the point where the mold halves meet, the prominence of which depends on the accuracy with which the halves are matched.
 
Multi-layer Bottles - Bottles comprised of layers of special plastic materials that are co-extruded to preserve and use the unique characteristics of each material to improve the barrier qualities of the container and increase the product shelf life.
 
Natural Color - Refers to the natural translucent appearance of the plastic material of containers and closures.
 
Neck Ring - The component of the molding apparatus that produces the bottle finish.
 
Paneling - The collapse of a portion of a container structure, due to a loss of interior pressure, which occurs during aging and storage.
 
Parison - The empty cylinder of plastic melt that emerges from the extruder die head and expands in the mold space from air pressure, producing the molded part.
 
Parting Line - The mark on a plastic bottle where the two halves of the mold meet at the point of closure.
 
Preform - A heat-softened polymer shaped like a thick test tube with neck threads that is inflated while inside a blow mold.
 
Programming - A procedure for mechanically altering the weight, size or wall thickness of the parison as it forms.
 
Shrinkage - A decrease in dimension of an article after the molding process, which is caused by the contraction of the plastic material upon cooling.
 
Side Seam
- The seam that joins both edges of a blank forming a body.
 
Surface Treating - Any treatment technique, including chemical, electronic and flame treatments, that makes plastic receptive to inks, lacquers and adhesives.