Relaxation of residual stresses in plastic cover lenses with applications in the injection molding process

Macías, César Morado; Meza, O.; Pérez, Elı́as

doi:10.1016/j.engfailanal.2015.07.026

Cited by 27 publications

(16 citation statements)

References 4 publications

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“…In addition, the residual stress in the center of tooth thickness direction is greater than that in other Due to various external factors, the disorder and relaxation of molecular chains in melt materials are destroyed. It makes the melt in an unstable state and produces residual stress [49,50]. In the process of molecular chain relaxation or recrystallization, the stress will be released, which leads to the shrinkage of related positions.…”

Section: Shrinkage Characteristics Analysis Of Small Module Plastic Gearsmentioning

confidence: 99%

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

2021

Polymers

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This paper was aimed at finding out the solution to the problem of insufficient dimensional accuracy caused by non-linear shrinkage deformation during injection molding of small module plastic gears. A practical numerical approach was proposed to characterize the non-linear shrinkage and optimize the dimensional deviation of the small module plastic gears. Specifically, Moldflow analysis was applied to visually simulate the shrinkage process of small module plastic gears during injection molding. A 3D shrinkage gear model was obtained and exported to compare with the designed gear model. After analyzing the non-linear shrinkage characteristics, the dimensional deviation of the addendum circle diameter and root circle diameter was investigated by orthogonal experiments. In the end, a high-speed cooling concept for the mold plate and the gear cavity was proposed to optimize the dimensional deviation. It was confirmed that the cooling rate is the most influential factor on the non-linear shrinkage of the injection-molded small module plastic gears. The dimensional deviation of the addendum circle diameter and the root circle diameter can be reduced by 22.79% and 22.99% with the proposed high-speed cooling concept, respectively.

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Section: Shrinkage Characteristics Analysis Of Small Module Plastic Gearsmentioning

confidence: 99%

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

2021

Polymers

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“…To approach the conditions experienced by a polymer leaving an extrusion die, out of calibration we first consider the effects of shrinkage free quenching, that is to say without considering that metal walls can hinder this withdrawal. Suppose that below a solidification temperature Ts, the polymer behaves like an elastic solid, with a modulus E and a Poisson's ratio ν, and above, like a liquid, which does not hinder the shrinkage [20].…”

Section: Theoretical Methodsmentioning

confidence: 99%

Experimental and Numerical Modeling the Effect of the Residual Stress in the Case of the Molding of a Plastic Part

Khlifa¹,

Lammari²,

Kharroubi³

2021

Mater. Plast.

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There is always time and energy optimization and reduction of faults the aim of research and in this context our article presents a study of a practical case of the deformation of a plastic part placed in a refrigerator for food storage, and that the use increases in number of these types of metals, are found in several sectors, and because of their industrial performance, a minimum residence time of the part in the mold is sought in order to reduce the cycle time of the process at the same time that the injection process is quite complex and requires a certain number of recurring questions to succeed. In the desired model. These are linked to residual stresses and deformations, pressure, mold temperature, filling threshold, shape of the part, but also to other mechanical and optical properties. Several investigations have been carried out and according to the authors the causes of these failures vary according to the manufacturing technique used. In this article, we try to find the origin of a deformation detected on a part at the end of the mold. Our work consists first of all in presenting, according to different studies, the thermomechanical properties of the material injected at different stages of the injection process. In a second step, compare the theoretical and analytical results. At the end of our study, we propose an optimization of the parameters necessary for the success of the molding and of the geometry of the assembly (mold and part).

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“…Plastic collimating lenses require precision manufacturing with high dimensional tolerances, avoiding any small warping in the geometry of the piece [ 6 , 7 , 8 , 9 ]. The collimating lens topology is characterized by its variable geometry, as well as its high thickness ratios, understanding this ratio as the relationship between the maximum and the minimum thickness of the lens [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

A New Conformal Cooling System for Plastic Collimators Based on the Use of Complex Geometries and Optimization of Temperature Profiles

et al. 2021

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The paper presents a new design of conformal cooling channels, for application in collimator-type optical plastic parts. The conformal channels that are presented exceed the thermal and dynamic performance of traditional and standard conformal channels, since they implement new sections of complex topology, capable of meeting the high geometric and functional specifications of the optical part, as well as the technological requirements of the additive manufacturing of the mold cavities. In order to evaluate the improvement and efficiency of the thermal performance of the solution presented, a transient numerical analysis of the cooling phase has been carried out, comparing the traditional cooling with the new geometry that is proposed. The evolution of the temperature profile versus the thickness of the part in the collimating core with greater thickness and temperature, has been evaluated in a transient mode. The analysis of the thermal profiles, the calculation of the integral mean ejection temperature at each time of the transient analysis, and the use of the Fourier formula, show great improvement in the cycle time in comparison with the traditional cooling. The application of the new conformal design reduces the manufacturing cycle time of the collimator part by 10 s, with this value being 13% of the total manufacturing cycle of the plastic part. As a further improvement, the use of the new cooling system reduces the amount of thickness in the collimator core, which is above the ejection temperature of the plastic material. The improvement in the thermal performance of the design of the parametric cooling channels that are presented not only has a significant reduction in the cycle time, but also improves the uniformity in the temperature map of the collimating part surface, the displacement field, and the stresses that are associated with the temperature gradient on the surface of the optical part.

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Relaxation of residual stresses in plastic cover lenses with applications in the injection molding process

Cited by 27 publications

References 4 publications

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

Experimental and Numerical Modeling the Effect of the Residual Stress in the Case of the Molding of a Plastic Part

A New Conformal Cooling System for Plastic Collimators Based on the Use of Complex Geometries and Optimization of Temperature Profiles

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