Compactness, durability, and low cost—everything that has been missing in many typical shutoff nozzles—are delivered by the new Mini-Shut nozzle, according to Md Plastics Inc., Columbiana, Ohio (mdplastics.com). Injection molders have used melt decompression to avoid stringing and drooling. But according to Michael Durina, head of Md Plastics, melt decompression can be the cause of other problems, like splay and inconsistent shot size. The answer, he says, is a shutoff nozzle that eliminates the need for melt decompression—as well as stringing and drool—and also allows simultaneous operation of the screw and clamp for faster cycles.
The Mini-Shut is a spring-loaded device designed to fit on almost all nozzle bodies, both American and European. It is short—1.5 to 2 in., vs. 6 to 24 in. for other shutoff nozzles—as well as long-lasting, low-maintenance, and low-cost—$225 to $300, vs. $1500 to $9000 for competing models, Durina says. He adds that it withstands up to 750 F, provides low shear and pressure drop, and can be easily cleaned by standard purging methods. The Mini-Shut is also distributed by DME Molding Supplies.
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This small component can cause big problems. Here’s my procedure for picking and replacing yours.