Abstract Injection molded plastics are widely used for mass production in auto industry. However, it is challenge to produce parts that do not warp. It is helpful to have an accurate way to measure the warpage when investigating and solving warpage issues. In this paper, a new technology is introduced to measure the part warpage quickly and accurately with the help of digital image correlation (DIC) method. The polypropylene plaque were fabricated by injection molding based on An L9 (3ˆ4) Taguchi design of experiments. The warpage of plaque are characterized for all the conditions and at different time after being ejected. Different kinds of warpage results are obtained by DIC method, such as maximum deflection, deflection distribution along desired path, warpage contour on the surface. The plaque warpage increases with the time. The maximum difference can reach as high as 64.9%. The cooling time has the largest influence on the warpage, while the packing pressure has the minor effect. Nevertheless, the warpage difference due to time varying depends on melt temperature, mold temperature, cooling time and packing pressure, in which mold temperature has the highest effects.
The most time-consuming phase of the injection molding cycle is cooling. Cooling efficiency can be enhanced with the application of conformal cooling systems or high thermal conductivity copper molds. The conformal cooling channels are placed along the geometry of the injection-molded product, and thus they can extract more heat and heat removal is more uniform than in the case of conventional cooling systems. In the case of copper mold inserts, cooling channels are made by drilling and heat rem...
Last. Jie Tao(NUAA: Nanjing University of Aeronautics and Astronautics)H-Index: 3
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The warpage of injection molded part strongly depends on the shrinkage property, which is highly dominant by the Pressure-Volume-Temperature (PVT) curves. Accurate description of PVT curves is essential for running the simulation of warpage. The standard PVT curves are measured at different pressure for the isotactic polypropylene, which are modified with the help of crystallizing curves obtained by the Differential Scanning Calorimetry (DSC) tests at different cooling rate. The user subroutine ...
#2Ming-Hung Li(NKFUST: National Kaohsiung First University of Science and Technology)H-Index: 1
Last. Ming-Shyan Huang(NKFUST: National Kaohsiung First University of Science and Technology)H-Index: 4
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Abstract Headlight lampshades with an uneven part thickness and large-area complicated geometry often exhibit uneven shrinkage and considerable deformation when fabricated using injection molding. Conventional strategies for controlling shrinkage and warpage involve optimizing the gate number and location, cooling system, and mold conditions and performing annealing in a secondary process; however, conventional strategies are limited in improving the quality of injection molding. This study invo...
#1M.D. Azaman(UniMAP: Universiti Malaysia Perlis)H-Index: 7
#2S.M. Sapuan(UPM: Universiti Putra Malaysia)H-Index: 82
Last. Abdan Khalina(UPM: Universiti Putra Malaysia)H-Index: 21
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Reducing volumetric shrinkages and warpage during the injection molding process is a challenging problem in the production of molded thin-walled parts. In this study, the injection molding of shallow, thin-walled parts (thickness 0.7 mm), composed of lignocellulosic polymer composites (polypropylene (PP) + 50 wt% wood), was simulated. The volumetric shrinkages and warpage in the thin-walled parts were evaluated under different process conditions, with varying post-filling parameters, such as mol...
#1Hui-Li Chen(Communist University of the Toilers of the East)H-Index: 2
#2Shia-Chung Chen(CYCU: Chung Yuan Christian University)H-Index: 25
Last. Yu-Tseng Lin(CYCU: Chung Yuan Christian University)H-Index: 1
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Abstract In mold decoration (IMD) injection molding is a relatively new multi-process technique that has been used for improving the surface quality and achieving colorful cosmetic surface of molded parts. During IMD processing, the film having the same shape as mold cavity is first inserted into the mold then molten polymer is injected into the cavity. Heat transfer in the cavity surface is significantly retarded because of the low thermal conductivity of film. As a result of the asymmetric mel...
#1R. Sánchez(CSIC: Spanish National Research Council)H-Index: 1
Last. Daniel Mercado(CSIC: Spanish National Research Council)H-Index: 3
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Abstract Injection molding process causes differences between designed shape and real parts, all of them associated to shrinkage phenomena. Temperature and pressure distribution during molding process originate local shrinkage, and the internal stresses induces warpage depending on the relative stiffness of each part area. In this paper some measurement results are shown, focused on cooling parameters effect on warpage, using non-contact techniques on several part areas. Results allow visualize ...
As a result of new aesthetical and economical requirements in injection molding, several processes have been developed during last years. In spite of conventional process, sequential injection molding is a versatile technique based on independent control for each gate opening. This procedure allows part filling without weld lines or, at least, these defects can be relocated in suitable positions. A short discussion about sequential principles is made introducing computer simulations. Pressure re...
Last. Shaofei Jiang(Zhejiang University of Technology)H-Index: 10
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Warpage is a typical defect for injection-molded parts, especially for crystalline parts molded by rapid heat cycle molding (RHCM). In this paper, a prediction method is proposed for predicting the warpage of crystalline parts molded by the RHCM process. Multi-layer models were established to predict warpage with the same thicknesses as the skin-core structures in the molded parts. Warpages were defined as the deformations calculated by the multi-layer models. The deformations were solved using ...
Last. A Rajeshkannan(USP: University of the South Pacific)
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The multi-stage sequential process with multi-objective is a complex problem to address as the decision made at a particular stage influences the subsequent stage and vice versa. In this article, t...