Problem & Solution

Practical answers to common plastic material challenges

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Q

Burnt / Black Speck

A

The fundamental mechanism of burning is that the local temperature exceeds the thermal decomposition temperature of the material. Solution priority: first improve mold venting (eliminate adiabatic compression), second control melt temperature and reduce residence time (prevent degradation in the ...

Injection Molding burntadiabatic compressionmold ventingmaterial retentionthermal degradation

Q

Weld Line / Confluence Mark

A

Weld lines cannot be completely eliminated but can be greatly reduced. The core strategy is to let the two melt streams converge under conditions of high temperature and low air resistance — increase mold temperature to slow down front cooling, improve venting to eliminate air cushion barrier, an...

Injection Molding weld linemelt temperatureventing designgate layoutmolecular diffusion

Q

Bubble / Void

A

The three major causes of bubbles (moisture, air entrainment, vacuum shrinkage cavities) need to be treated differently: moisture type — full drying; air entrainment type — optimize plasticizing and injection parameters; vacuum shrinkage cavity type — strengthen holding pressure feeding. Accurate...

Material Drying bubbleraw '2079851475616104451back pressure controlvacuum shrinkage cavitymold venting

Q

Sink Mark / Depression

A

The essence of sink marks is that local volume shrinkage cannot be compensated by feeding. The core countermeasure is to establish and maintain an effective feeding channel — set the gate near the thick-wall area, extend the holding time until after the gate freezes, and at the same time reduce t...

Molds & Tooling sink markholding pressure feedingcooling timewall thickness designgate position

Q

Flash / Burr

A

The root cause of flash is that the mold-opening force generated by the cavity internal pressure exceeds the closing force of the clamping system. The logic chain of the solution is: first reduce the cavity pressure peak through process adjustment, then check and repair the clamping system to ens...

Injection Molding flashclamping forceparting line gapcavity internal pressureburr

Q

Short Shot / Insufficient Filling

A

The essence of short shot is that the melt flow ability is insufficient to overcome the cavity filling resistance. The core solution idea is "exerting force in both directions": reducing flow resistance (optimizing mold venting and gate design) and enhancing flow drive (increasing injection press...

Injection Molding insufficient fillinginjection pressuremelt temperaturemold ventinggate design

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