A hot runner system is an integration of heated components used primarily in plastic injection molds. It helps inject molten plastic into the hollow cavities of the mold. Where as, a cold runner system is simply a channel in between the two halves of the mold, designed to carry plastic from the injection molding machine to the cavities.
Every time the mold opens up to eject the newly formed plastic parts, the runner material is ejected too. This result in the wastage of the plastic deployed. On the contrary, a hot runner system includes a heated manifold. The primary purpose of the heated manifold is to allocate the plastic entering in the mold to the various nozzles and measure the injection points in the cavities.
The concept of runner systems was first brought in inception in the early 60s with a lots critique. The idea gained popularity in the 80s and 90s as technological development improved and enhanced the quality of the plastic material prices. This raised the demand of hot runner systems as it was cost effective. Such kind of systems is generally complicated and has to maintain the plastic material within them so as to check that the plastic is uniformly heated or not.
But the rest of the injection mold is being cooled to solidify the product immediately. This is the reason behind integration of such parts by specialized companies. There are two types of runners available, one that is heated internally and the other that is externally heated. In the internal one, the plastic overflows over slender heaters. The outer boundary of the runners usually solidifies making a hollow cavity that allows plastic material flow in the proximity of the internal heater.
The injection PET blow molding machine is designed on an extruder barrel and screw assembly that melts the polymer. The molten polymer is fed into a hot runner manifold where it is interposed through nozzles into a heated cavum. The cavity mold forms the external shape of Perform. The Perform consists of a fully formed bottle/jar neck with a thick tube of polymer. Altogether, to conclude, hot runners make the mold more high-priced to manufacture and run, but initiate savings by reducing plastic waste and by reducing the production cycle time.