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April 1, 2000

2 Min Read
Hot Runner Tip For InjectionStretch Blow Molding Improves PET Preforms

Hot Runner TipFor InjectionStretch BlowMolding ImprovesPET Preforms

1npelogo4c.jpggroupimage29.jpgBased on patented 'short gate technology,' a new hot runner tip from R & D Tool And Engineering is said to produce PET preforms with shorter, cleaner gate vestiges. This is said to translate into higher quality bottles, no secondary gate clipping operations and fewer rejects.

The new tip design is offered as an option on the firm's line of molds for one-step injection stretch blow molding applications.

Another advantage sited for the new design is that it is a 'thermal break' tip as opposed to a valve gate tip. This is claimed to eliminate the need for a pneumatically or hydraulically operated valve shut-off pin. This is accomplished with an insert extending beyond the manifold nozzle cap sealing surface into an injection mold cavity cutout, forming a material outlet space from the passage inlet with a predetermined gap.

The cutout receives plastic material from the nozzle tip, which has an outlet that surrounds and thermally insulates the tip from the injection mold cavity. This insulation gap helps to create consistent short gates without stringing.

The result is a hot runner with less maintenance and downtime. The manufacturer adds that the new technology produces finished preforms with gates as good as, or better than, those produced with valve gate tips.

The reduction in gate length in the preform is said to provide other advantages, as well. The first is that preforms coming off the mold are ready for the blow stage with no secondary operations. Short gates mimic clipped gates by allowing for bottle designs with short crown/push-up heights. With less gate to contend with and compress, gate clearance to seating surfaces problems are eliminated.

Another benefit of short gates is that their volume is easily compressible during the blow cycle. This is said to aid in improved, more uniform material distribution along the container, where previous long-gate designs could become cold, fold over and pull material to one side,causing a higher number of unacceptable preforms.

Prices vary depending on a number of factors, so please contact the manufacturer directly by using the Key Contact Directory on p 50.

R & D Tool AndEngineering, Inc.
Lees Summit, MO

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