Papers by Keyword: Cavity Pressure

Abstract: This work is focusing on optimization of the chosen process conditions (melt temperature, injection rate and holding pressure) and their mutual interaction on the local shrinkage of wall thickness carried out on rectangular plate. The test was applied on semicrystalline polymer in following modifications - polypropylene homopolymer and 40 % talc filled polypropylene. For better understanding of processes influencing shrinkage the pressure evolution inside cavity was captured by transducers placed near the gate and at the end of flow.

Abstract: The existence of variations in the injection molding process conditions leads to the inconsistency of molded parts quality during the molding cycles. In this research, the variations of cavity pressure-time profiles integrals over the molding cycles were accounted as the molded parts quality variations. Thereafter, the correlations between injection molding process settings and the degree of consistency of molding process were investigated by applying cavity pressure measurement, Taguchi design of experiments approach and signal to noise ratio. The results derived from experiments indicated that an increase approximately as high as five times in the capability of injection molding may be achieved. Under the best setting condition, the cavity pressure profiles were relatively smooth and similar. Low screw rotational speed, high injection speed and short packing time led to the inconsistency elevation of injection molding.

Abstract: At first this paper described the cavity pressure monitoring technology definition and work principle. Then showed that made use of monitoring the cavity pressure curve and study melt flow balance by specific example. The use of cavity pressure curve could be quickly and accurately get the best process parameters, so change the way of obtaining process parameters optimization from the "experience" basis to "scientific" basis. The article concluded it could understand deeply and grasp the relationship among the three proposals of the cavity pressure curve, process parameters and product quality.

Abstract: At first this paper described the cavity pressure monitoring technology definition and work principle. Then showed that made use of monitoring the cavity pressure curve and study melt flow balance by specific example. The use of cavity pressure curve could be quickly and accurately get the best process parameters, so change the way of obtaining process parameters optimization from the "experience" basis to "scientific" basis. The article concluded it could understand deeply and grasp the relationship among the three proposals of the cavity pressure curve, process parameters and product quality.

Abstract: The characteristic of injection compression molding technology and the application of the technology in mould for the plastic optical lens were introduced. The structure and the work principle of the mould for optical lens were designed and described, The stress problem in the injection process was resolved, the deformation problem and dimensional accuracy of product were improved.

Abstract: Filling-to-packing switchover control during injection molding plays a crucial role in ensuring the quality of the molded parts. In this study, a filling-to-packing switchover mode based on cavity pressure was presented, and it was compared with other two switchover modes by injection time and screw position. The objective of this study was to validate the accuracy of the switchover mode based on cavity pressure, and examine its consistency. Weight of the molded parts served as the main measure to probe the process capabilities. In this study, the change in mold temperature was monitored; variation of mold temperature affecting the process was examined. The results of the verification experiments revealed that the switchover mode based on cavity pressure could yield a better part quality and consistent part weight compared with the other two traditional switchover modes. It was proved that the switchover mode by cavity pressure can be used to improve the precision of the injection molding. However, a suitable switchover pressure must be used for achieving such high process capability, and the position to get the pressure signal and mold temperature should also be considered.

Abstract: The packing stage is the most important stage to plastic parts quality. If the packing curve is not set reasonably, non-uniform distribution of pressure is caused in injection mold cavities, which results in that plastic parts emerge a series of quality problems, such as: warpage, sink marks, and poor dimensional accuracy. Taking into consideration complexity of in the cavities in the packing stage, this paper set packing curve two stages. First stage packing pressure was set at constant so that cavity pressure also kept constant tendency, thus difference of shrinkage rate was reduced, and second stage was set at linear decreasing so that packing pressure hold consistent with cavity pressure that gradually decreased to zero with the melt curing, thereby residual stress was reduced. The packing curve values were optimized, by balancing cavity pressure that is the intermediate variables time after time by the numerical simulation technology. The best packing curve was ultimately got.

Abstract: While the switchover from filling to packing is particularly crucial during injection molding, the transfers from holding to screw recovery also significantly affects the quality of molded parts. In this study, the end-point control of the holding phase based on cavity pressure was presented. It was compared with the traditional control method by holding time. The purpose of this study was to validate the feasibility of the end-point control of holding phase by cavity pressure, and to examine its consistency. The weight of the molded parts served as the main measure to probe the process’s capabilities. The results of the verification experiments revealed that the end-point control mode based on cavity pressure could yield better consistency of part weight than the traditional control method by holding time, however, the benefits were not significant. The trigger value of cavity pressure and sensor position should be considered for achieving such high process capabilities.