Hot melt gun modules are high pressure fluid valves. These are typically attached to heated hot melt gun manifolds for quick and easy removal to minimize line downtime when they do not shut off completely. Incomplete shut off results in extended patterns, leaking, dripping or the “stringing” of the hot melt adhesive.

In these modules a needle valve lifts off the internal seat with compressed air or electric coil. It closes with compressed air or a spring. This action stops the hot melt flow between the needle tip and the needle seat which then flows into and through a nozzle tip onto the
substrate. When the needle is forced down against the seat with compressed air or compressed spring the flow of adhesive is, or should be, stopped completely. Adhesive in the typical hot melt system can be pressurized to over 1000 psi making the intimate seating of the needle
and seat critical.

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Hot Melt Modules - Leaking, Dripping and Stringing - by Pierce Covert,
Glue Machinery Corporation
www.gluemachinery.com