The influence of level of interfacial healing on the weld-line strengths of injection molded parts
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Chung-Ching Huang
Abstract
Weld lines are commonly present within injection-molded plastic components and generally reduce strength. In designing a plastic part, the designer can often vary the wall thicknesses, or move the gate locations to position the weld line, so that its structural loading is minimized. By altering such variables as melt temperature, mold temperature, and packing pressure, slight increases in weld-line integrity can be achieved. These approaches often do not increase the part strength or performance to an acceptable level, resulting in the exclusion of numerous applications for plastic conversion. This study investigated a hot runner system, sequential valve gates, and heat degree, to achieve economical methods for predicting weld-line properties. By calculating melt front temperatures with MoldFlow analysis, we can predict the strength of the weld line according to the definition of “heat degree”, which is the effective cross-sectional area of the melt front multiplied by the temperature gradient. An effective cross-sectional area of the melt front is defined as the area of the temperature above the melting point. In contrast to the test result, when the “sum of heat degree” is lower than 1150 mm2 °C for PA6 (Mitsubishi 1030J) and 500 mm2 °C for polypropylene (PP) (FCFC K1012), the molecules cannot bond adequately at the interface of the melt fronts. Therefore, the mechanical property declines significantly.
©2012 by Walter de Gruyter Berlin Boston
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Articles in the same Issue
- Masthead
- Masthead
- Review
- Influence of hydrostatic pressure and volumetric strain on the mechanical long term behavior of polymers
- Original Articles
- Dynamic pressure analysis as a tool for determination of sharkskin instability by extrusion of molten polymers
- Young’s modulus and prediction of plastics/elastomer blends
- Comparison of tribological performance of PEEK, UHMWPE, glass fiber reinforced PTFE and PTFE reinforced PEI composite materials under dry and lubricated conditions
- Study on the solidification kinetics of high-density polyethylene during thin-walled injection molding process
- The influence of level of interfacial healing on the weld-line strengths of injection molded parts
- Investigation on Nylon 66 silicate nanocomposites modified under gamma radiation
- Effect of mold surface antistiction treatment on microinjection replication quality using Cr-N/Zr-DLC thin-layer coating
- Estimation of thermal conductivity of PP/Al(OH)3/Mg(OH)2 composites
- Preparation and characterization of polyvinyl alcohol/carbon nanotube (PVA/CNT) conductive nanofibers
- Copolymerization of 5-norbornene-2-metheneoxy-trimethylsilyl with methyl 5-norbornene-2-carboxylate catalyzed by a novel Ni(benzocyclohexan-ketonaphthylimino)2/B(C6F5)3) system
- A modified polyurethane elastomer using polyfunctional HTPB synthesized by in-situ nitroxide mediated polymerization of 1,3-butadiene
- Preparation and characterizations of ternary biodegradable blends composed of polylactide, poly(ε-caprolactone), and wood flour
- Polypropylene + boehmite nanocomposite fibers
- Development of PCL-PEG nanofibrous mats as alternative carriers for recombinant Chinese hamster ovary cells
