Papers by Keyword: Warpage

Abstract: Injection molding is one of the most important processes in manufacturing nowadays. Thus, attention must be give towards the optimization of the product defects. Parameters have been chosen by screening tests to improve the process quality. The main purpose of this study is to optimize the processing condition using Taguchi Method on shrinkage for HDPE-Clay specimen. The experiment starts by preparing the mixture between HDPE and clay. Then, screening test is conducted to obtain the parameters. The parameters are melt temperature, injection speed, injection pressure and cooling time. By using the array orthogonal L₉ (3⁴), signal to noise ratio and ANOVA were conducted. Based on the S / N ratio analysis, best combination can be produced for warpage (melt temperature: 190°C, injection speed: 40%, injection pressure: 30% and cooling time: 3 seconds). While for ANOVA, melt temperature is most significant with 60.28% for warpage.

Abstract: In order to study the influence of process parameters on forming quality of printer board with metal-insert,shorten the development cycle,reduce the enterprise cost,the warp trend and reasons of injection process parameters,including packing time,hold pressure,mold temperature,melt temperature,on the warpage of the part were analyzed by means of software moldflow. The results show that warpage amounts decreases with packing time and hold pressure increasing,larger packing time and longer hold pressure is advantageous to the injection parts molding;And warpage amounts increases with mold temperature and melt temperature increasing,the lower mold temperature and melt temperature is advantageous to the injection parts molding;Among the four parameters,the melt temperature had the greatest influence,followed by the mold temperature and the hold pressure,packing time had the minimal influence on the warpage.

Abstract: High-gloss injection molding technology is also called rapid cool and heat injection technology which can be used to eliminate weldmark on the surface of plastic parts, and improve the surface glossiness. However, the warpage, sink index and volume shrinkage of the parts are considered difficult to solve by using this technology. Reasons that cause the warpage and sink index of the parts were discussed in this paper firstly. Then, by using a LCD panel produced in practical injection process as an example, through orthogonal experimental design and finite element simulation, this paper discusses the effects of the injection molding parameters such as mold temperature, melt temperature etc. on warpage and sink index of the parts. The results are of great significance to help to set practical process parameters and assure the part quality in injection process.

Abstract: Thermo-mechanical process simulation of an industrially pultruded rectangular hollow profile is presented. Glass/polyester is used for the continuous filament mat (CFM) and the uni-directional (UD) layers. The process induced residual distortions together with the temperature and degree of cure are predicted using a three dimensional (3D) thermo-chemical model sequentially coupled with a 2D quasi-static generalized plane strain mechanical model. The predicted deformation pattern at the end of the process is found to agree quite well with the one observed for the real pultruded parts in a commercial pultrusion company. In addition, the predicted warpage behaviour is further analysed by adjusting the mandrel length as well as including the mandrel heating. Using the proposed process model, the effect of the mandrel configurations on the quality of the pultrusion is investigated in terms of temperature, degree of cure and distortions.These unwanted residual distortions may lead to not meeting the desired geometrical tolerances e.g. warpage of pultruded window frames and hollow profiles as well as spring-in of L-shaped profiles, etc.

Abstract: Reducing volumetric warpage during the injection molding process is a challenging problem in the production of microfluidic chips, as the warpage directly affects the bonding quality of the substrate and the cover sheet. In this study, the injection molding of substrate and the cover sheet, composed of PolymethylMethacrylate(PMMA), was simulated. The effect of different process parameters, holding pressure, holding time, mould temperature and injection speed, were investigated via single factor experiments, observing the warpage of the sheet with Three-Coordinate Measuring Machine. The analysis showed that the warpage was affected by non-uniform shrinkage and residual stress of the melt. Holding pressure and holding time had a greater effect on the warpage than the mould temperature and injection speed did. Therefore, reasonable holding pressure and holding time can effectively reduce the warpage of microfluidic chips in the injection molding process.

Abstract: This Paper Presents the Optimization of Injection Molding Conditions to Minimize the Warpage and Volumetric Shrinkage Using Design of Experiments and Taguchi Optimization Method. Considering the Process Parameters such as Injection Time, Packing Pressure, Packing Pressure Time, and Cooling Time, a Series of Mold Analysis are Performed. Orthogonal Arrays of Taguchi, the Signal-to-Noise(S/N) and Analysis of Variance (ANOVA) are Utilized to Determine the Optimization Parameter Levels and to Find out Principal Processing Parameters on Warpage and Volumetric Shrinkage. from the Results it is Clear that Warpage and Volumetric Shrinkage are Reduced. also, the Dominant Parameters were Cooling Time and Packing Time for Warpage, on the other Hand, the most Important Factor for Shrinkage was Injection Time. from this, it can be Concluded that Taguchi Method is very Suitable to Solve the Warpage and Volumetric Shrinkage Problems in Injection Molding Parts.

Abstract: Thin walled plastic parts are subjected to warpage after injection. Warpage can be overcome by the ribs features. This experimental project is to design a honeycomb ribs replacing the normal ribs to overcome part warping. The parameters included ribs height, the ribs thickness and the honeycomb size. Finite Element Analysis (FEA) simulations for each honeycomb ribs design are analyzed with Autodesk Moldflow Insight software and the part which result the worst warping value, part with medium warping value and part with less warping value were chosen to validate them by fabricating the core and cavity inserts to produce the actual product. The part warping is measured and then compared with the data from the simulation. Thus, the best design parameter of honeycomb ribs is identified.

Abstract: The optimization of processing parameters on warpage of polypropylene (PP) in the application of injection moulding machine was studied. The appropriate parameters were adjusted to reduce the warpage defect on the tensile test specimen of dumbbell. The type of injection moulding machine used in this research is Arburg 420C 800-250C. Four parameters that have been investigated; injection pressure, clamping pressure, back pressure and holding pressure. A concept of design of experiment (DOE) has been applied using Taguchi method to determine the suitable parameters. To measure the warpage of the dumbbell, digital height gauge was used to measure the flatness of the part surface. According the analysis of variance (ANOVA), the most significant factor that effect the warpage was holding pressure by 57.82%, followed with back pressure by 25.75%, clamping pressure by 16.27% and injection pressure by 0.16%. It is found that the optimum parameters setting that have been obtained were injection pressure at 950 bar, clamping pressure at 600 kN, holding pressure at 700 bar and back pressure at 75 bar. The depreciation value of warpage minimum index in this experiment was decreased by 4.6% after confirmation run.

Abstract: In this study, a mold is designed in single and dual type of gate in order to investigate the deflection of warpage for thick component in injection molding process. Autodesk Moldflow Insight software was used as a medium for experimental tested. Nessei NEX 1000 injection molding machine and P20 mold material details were entered in this study to get more accurate data on top of Acrylonitrile Butadiene Styrene (ABS) as a molded thermoplastic material. Taguchi orthogonal array, analysis of Signal to Noise (S/N) ratio and Analysis of Variance (ANOVA) were implemented to get the best combination of parameter and significant factor that affect the warpage problem for both types of gates. Coolant inlet temperature, melt temperature, packing pressure and packing time are the selected parameter that used in this study. A conformation test is conducted to verify the combination parameters optimized. From the result, multi gates used was founded that can decrease the deflection of warpage for thick product. From ANOVA, the most significant factor is melt temperature for single gate, and coolant inlet temperature for multi gate. Packing pressure and packing time were slightly influence on warpage problem for both studies.

Abstract: Two types of injection molded parts including parts with thin shell feature and parts molded with radial flow pattern are highly susceptible to the warpage. In this research, the warpage performance of a thin and centrally-gated disk was experimentally investigated. The melt pressure-time traces of two different locations inside the mold cavity were monitored by employing piezoelectric transducers. The results indicated that the pressure difference magnitude of melt at two locations along the radial flow path is related to the extent of molded part deformation. Moreover, it was pointed out that the high magnitude of warpage is because of two conflicting actions in the molded part comprising expansion as a result of viscoelastic recovery in the central region, and thermal contraction in the edge region of the thin disk. The molding variables encompassing injection speed, holding pressure, back pressure, mold temperature and screw rotational speed affected the thin disks deformation in order of significance.