Cavity Pressure (cavity + pressure)

Distribution by Scientific Domains

Selected Abstracts

Online control of the injection molding process based on process variables

Walter Michaeli
Abstract The conventional control of the injection molding process is based on machine variables, which cannot sufficiently characterize the course of the process. Hence, a system that controls the injection molding process based on process variables has been developed at the Institute of Plastics Processing at RWTH Aachen University during the last years. It controls the quality determining process variable cavity pressure directly and realizes a desired course of cavity pressure in the injection and holding pressure phases. The cavity pressure course in the holding pressure phase is controlled online on the basis of pvT behavior of the processed plastic material. Thus, an optimal course of the process in the pvT diagram can be guaranteed and the quality constancy of the molded parts can be clearly increased. Using the pvT-based process control, the effect of varying mold and melt temperatures on the molded part weight can be decreased by about 90% compared with the conventional process control. 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:65,76, 2009; Published online in Wiley InterScience ( DOI 10.1002/adv.20153 [source]

Cavity pressure control during cooling in plastic injection molding

B. Pramujati
Abstract Cavity pressure control during filling, packing, and cooling phases is imperative for maintaining product quality in injection molding process. This paper presents the design and implementation of a strategy to control cavity pressure profile during the cooling phase. In order to do this, a controlled variable parameter was defined to be the time constant , of the pressure profile. This parameter can be used effectively to control the shape of the cavity pressure over the cooling cycle. The coolant flow rate through the mold was used as the manipulated variable. A predictive control system was designed and implemented successfully to allow monitoring and control of , at several setpoints ,sp resulting in good and effective cavity pressure control. 2006 Wiley Periodicals, Inc. Adv Polym Techn 25:170,181, 2006; Published online in Wiley InterScience ( DOI 10.1002/adv.20068 [source]

A comparison of seven filling to packing switchover methods for injection molding

David O. Kazmer
The effectiveness of seven methods for controlling switchover from the filling to packing stage were investigated, including: (1) screw position, (2) injection time, (3) machine pressure, (4) nozzle pressure, (5) runner pressure near the sprue, (6) cavity pressure near the gate, and (7) cavity temperature at the end of flow. The activation threshold for each of the seven switchover methods was iteratively determined so as to produce similar part weights relative to a standard process. A design of experiments was implemented for each of the seven switchover methods that perturbs the process settings by an amount equal to six standard deviations of the standard process so as to replicate the expected long-term process variation. The results suggest that conventional switchover methods (e.g., screw position) had lower short-term variation, but other methods were more robust with respect to rejecting long-term process variation. The merits of different dimensional measurements for quality control are also discussed relative to the society of the plastics industry (SPI) standard tolerances. POLYM. ENG. SCI., 50:2031,2043, 2010. 2010 Society of Plastics Engineers [source]

Compression process effects on filling density and replication properties of micro-surfaces during metal injection molding

Kenji Okubo
Abstract To improve the surface replication properties and density of final metal injection molded (MIM) products, injection-compression molding was applied to metal-mold processing. Effects of the mold temperature and compression process conditions, such as the compression period, on the density, surface roughness, and geometry of green compacts and sintered products were investigated. The density of green compacts, cavity pressure inside the mold, and surface roughness were improved for longer compression periods of both pressure and volume control methods. Micro-scale replication properties for the V-grooves of green compacts revealed a complicated tendency involving the compression period and control method. The V-groove replication properties improved with increasing compression period, except for the volume control method and lower mold temperature. The sintered MIM products' final properties strongly affect the characteristics of green compacts. The injection-compression process for MIM products, e.g. metal,polymer complexes, can improve the surface replication properties and roughness of green compacts. Copyright 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]