plastic injection molding using insulated runner molds, an excellent option when a large number of plastic parts need to be manufactured quickly.

Advantages Over Hot Runner Systems
Properly designed insulated runners, with thermally controlled gates, offer several advantages over hot runner mold systems, including:

Dependable reproduction – no “dead spots” in mold

Uniform temperature distribution – thermal insulation forms through melt deposited at the wall

Economical process for continuous operation of uniform cycles without extended interruptions

Easy to maintain – quick to clean

Fast production color changes

Molds are less expensive to build and to maintain than hot runners

Minimal heat loss – thermal equilibrium reached quickly

Low energy input on startup – reduces energy cost

More consistent volume of polymer per part

Faster molding cycles

Elimination of runner scrap — less regrind

Improved part finish

Decreased tool wear

Insulated runner systems are inexpensive alternatives to traditional hot runners, where the mold is not heated, but the runner channels are extremely thick and stay molten during continuous cycling.

This feature provides the flexible gating advantages of hot runners without the added cost of the manifold and drops of a heated hot runner system.

Cold Runner Molding Has Advantages
However, as with hot runners, the insulated runner system also has disadvantages when compared to cold runner molding in certain situations. The increased level of technology required to manufacture and operate the insulated mold results in:

More complicated mold design

Higher mold costs

More difficult start-up procedures

Possible thermal degradation of the polymer melt

More difficult color changes than with cold runners