INJECTION MOLDING ENCYCLOPEDIA
Injection Molding Encyclopedia
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84 articles
Causes of Short Shots: Gate Temperature, Flow Length Ratio, and Incomplete Filling
Missing sections at the far ends or in thin walls indicate short shots (incomplete filling). Unlike clogged nozzles, which stop flow entirely, short shots occur when the melt halts mid-fill. Identify the root cause before troubleshooting.
Weld Line Formation: Confluence Point, Front Temperature, and Interface Fusion
Fine lines on part surfaces that are lighter in color and cannot be polished. These appear at hole edges, insert sides, or flow meeting points. Caused by insufficient melt temperature preventing proper fusion when two flow fronts meet.
Black Specks: Melt Carbonization, Residence Time, and Dead Zone Residue
Dark spots (0.x–1.x mm) on or below the surface that cannot be polished; these may appear in fixed or random locations. Often mistaken for dirt, but they persist even with new resin, indicating residue in the hot runner or screw.
Causes of Color Variation: Melt Temperature, Residence Time, and Purge Residue
Color variation may appear as darker areas near the gate, yellowing at the far end of the same part, or batch-to-batch mismatches that require multiple shots to stabilize after a color change. Often dismissed as "material issues," it is critical to distinguish between uniform shifts across the entire mold and localized variations.
Open-Nozzle Hot Runners in Connector Molding: LCP vs. PA9T Field Test
Stringing and drooling in connector injection molding are typically addressed through machine tuning and post-processing. This field test compares open-nozzle hot runners with active temperature switching against constant-temperature runners in LCP and PA9T, focusing on gate condition and yield.
LCP Automotive Connectors: Gate Defects and Processing Guide
As automotive electronics evolve, LCP is increasingly used in under-hood and high-density connectors. Its heat resistance, dimensional stability, flame retardancy, and flow properties make it well-suited for this application. However, issues like stringing, drooling, and gate clogging remain production challenges.
LCP Micro Connectors for Consumer Electronics: Precision Molding Requirements
Micro-connectors in phones, earbuds, watches, and tablets are becoming increasingly compact in pitch and wall thickness. While LCP is widely used for its excellent flow and dielectric properties, smaller parts suffer more from gate stringing, drooling, and clogging, which reduce yield.
LCP Industrial Connectors: Reliability, Gate Carbon, and Changeover
Industrial connectors must remain reliable despite temperature swings, vibration, oil exposure, and long service life. LCP meets these demands, but high-mix, low-to-mid-volume production introduces challenges in gate carbon buildup, material changeovers, and maintenance.
LCP Medical Connectors: Purity, Extractables, and Dimensional Control
Medical connectors must be reliable, clean, and compatible with repeated disinfection. LCP is ideal for miniature medical components due to its resistance to disinfectants and dimensional stability, though gate black spots, residue, and marks require stricter process control.
Which Molding Projects Suit FHFC Hot Runners? Four Key Checks
FHFC hot runners are not suitable for every molding project. This technology controls local gate temperature to address stringing, drooling, and clogging. It is not a whole-mold FHFC solution and does not resolve weld lines, surface appearance, or warpage. Material selection, part design, existing defects, and production volume provide the initial basis for assessment.
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