Thermal Resistance at the Polymer/Mold Interface in Injection Molding

Nathan, D. Kamala; Prabhu, K. Narayan

doi:10.1007/s12666-021-02420-5

Cited by 6 publications

(5 citation statements)

References 98 publications

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“…Review papers by Heinle and Drummer, 9 Xian et al, 12 and Nathan and Prabhu 14 provide comprehensive summaries of TCR measuring techniques, including discussion on advantages and limitations. However, a direct comparison of TCR data obtained with the two methodologies has not been proposed.…”

Section: Literature Reviewmentioning

confidence: 99%

“…As such, the results reported by various researchers are still sparse, as summarized in literature reviews. [12][13][14] 2 | LITERATURE REVIEW…”

Section: Introductionmentioning

confidence: 99%

“…However, despite significant efforts and extensive research, a wide range of TCR values is reported in the literature without generally applicable models. As such, the results reported by various researchers are still sparse, as summarized in literature reviews 12–14 …”

Section: Introductionmentioning

confidence: 99%

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Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

Masato,

Kazmer,

Gruber

2023

Polymer Engineering & Sci

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This article provides the first multivariate analysis of reported thermal contact resistance (TCR) values from different characterization approaches (injection and compression molding) having missing data. The missing data are estimated by principal components analysis (PCA) with alternating least squares (ALS), and then the main effects are modeled using multiple regressions. Three models of increasing complexity are presented, each of which provides reasonable model fidelity relative to the TCR values reported in the literature. The primary cause of differences between reported TCR values as characterized by injection molding and compression molding can be explained by the melting of the polymer to make intimate contact with the metal mold during processing. Typical values of TCR are on the order of 0.0002 m2K/W, corresponding to heat transfer coefficients of 5000 W/(m2K). The analyses suggest that the TCR decreases significantly with increasing processing temperature and pressure but increases most significantly during cooling with the development of an air gap between the polymer and mold. Accordingly, it is strongly recommended that injection molding simulations incorporate modeling of the TCR as a function of the processing states for accurate prediction of the air gap, residual stresses, shrinkage, and warpage.Highlights Multivariate analysis of thermal contact resistance data from the literature. Sparse data handled by principal component analysis and alternating least square. Comparison of injection molding and compression molding measurements. Results suggest thermal contact resistance should be modeled as a function of the processing states.

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Section: Literature Reviewmentioning

confidence: 99%

“…As such, the results reported by various researchers are still sparse, as summarized in literature reviews. [12][13][14] 2 | LITERATURE REVIEW…”

Section: Introductionmentioning

confidence: 99%

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Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

Masato,

Kazmer,

Gruber

2023

Polymer Engineering & Sci

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“…21 TCR values at the polymer/mold interface under various process conditions are documented in review articles. 22,23 The initial packing of the melt inside the mold establishes perfect contact at the interface with low TCR values. During cooling, an increase in TCR is primarily attributed to the formation of an insulating air gap as the polymer shrinks.…”

Section: Introductionmentioning

confidence: 99%

“…TCR values at the polymer/mold interface under various process conditions are documented in review articles 22,23 . The initial packing of the melt inside the mold establishes perfect contact at the interface with low TCR values.…”

Section: Introductionmentioning

confidence: 99%

Polymer/mold interfacial heat transfer during injection molding

Nathan,

Prabhu

2023

Polymer Engineering & Sci

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An experimental injection molding setup was designed and fabricated. The purpose of the setup is to cast polymer components and estimate the polymer/mold interfacial heat flux transients during injection molding. The mold plate is instrumented with K‐type thermocouples to record its thermal history continuously during the cyclic process. Experiments were performed at a melt injection temperature of 280°C. Velocity and shear rate profiles were determined to assess the flow behavior of the melt. The spatiotemporal heat flux transients at the interface and the mold surface temperature were estimated using measured temperature data inside the mold as input to an inverse heat conduction problem. The estimated boundary heat flux transients were used to numerically simulate the polymer melt's cooling behavior. From the estimated heat flux and surface temperatures, heat transfer coefficients (HTC) were determined. The peak value of the HTC was 5775 W/m2K and occurred at a mold surface temperature of 35.7°C and polymer surface temperature of 47.4°C. The evolution of the air gap at the interface was quantified using an exponential fit. The estimated air gap width corresponding to peak HTC was about 4 μm and increased to about 100 μm towards the end of the solidification. While the peak heat flux is associated with the start of the formation of polymer skin on the mold surface, the peak HTC corresponds to the onset of nucleation of the air gap or a nonconforming contact.Highlights An experimental setup to study heat transfer during injection molding. Spatiotemporal heat flux transients (q) were estimated during injection molding. Polymer temperatures were simulated using q, and HTC was determined. The peak HTC indicated the onset of nucleation of an air gap. Evolution of air gap at the interface was modeled using an exponential fit.

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Cooling System Design

Kazmer

2022

Injection Mold Design Engineering

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Thermal Resistance at the Polymer/Mold Interface in Injection Molding

Cited by 6 publications

References 98 publications

Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

Meta‐analysis of thermal contact resistance in injection molding: A comprehensive literature review and multivariate modeling

Polymer/mold interfacial heat transfer during injection molding

Cooling System Design

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