Injection molding computer simulation

Developments. A variety of process modifications aimed at improving surface finish or weld line integrity have been described. They include gas assisted, co-injection, fusible core, multiple five feed, and push-pull injection molding (46,47). An important development includes computer-aided design (CAD) methods, wherein a proposed mold design is simulated by a computer and the melt flow through it is analyzed (48). 

Fig. 13.42 Simulation results of the RIM process involving a linear step polymerization T0 = Tw = 60°C, kf— 0.5L/moles, t(lii = 2.4 s. (a) Conversion contours at the time of fill, (h) Temperature contours at the time of fill. [Reprinted hy permission from J. D. Domine and C. G. Gogos, Computer Simulations of Injection Molding of a Reactive Linear Condensation Polymer, paper presented at the Society of Plastics Engineers, 34th Armu. Tech. Conf, Atlantic City, NJ, 1976. (Also published in the Polym. Eng. Sci., 20, 847-858 (1980) volume honoring Prof. B. Maxwell).]...

J. D. Domine, Computer Simulation of the Injection Molding of a Liquid Undergoing a Linear Step Polymerization, Ph.D. Thesis, Department of Chemical Engineering, Stevens Institute of Technology, Hoboken, NJ, 1976. 

The choice of the proper cooling time is also especially important from the profitability aspect. Apart from the comphcated equations for defining the cooling process-as applied in computer simulations of injection molding-there are also simple equations which make it possible to calculate cooling times with a pocket calculator or by hand. 

The ultimate result of Computer Integrated Injection Molding (CUM) in software packages is to translate the results of computer simulation of the molding of a specific part into machine settings for specific microprocessor-controlled machines (Fig. 2-16). CUM automates the entry of a large number of set points (Figs. 2-2 and 2-13) in microprocessor-controlled machines and maximizes their efficiency, on the basis of extensive development by Ernest C. Bernhardt (Plastics Computer Inc., Montclair, NJ 07042, USA), a world leader on this subject (110, 111). 

In the 1970s, attention turned to simulation of injection molding of thermoplastics, with the first papers concerned with either isothermal mold filling [R8, W8] or nonisothermal filling very simple molds [Kl]. From the late 1970s, commercial computer software for simulating nonisothermal injection... 

The mold temperature, on the other hand, affects the thickness of skin layers [82,83,87]. In general, the effect of temperature on the mechanical properties is relatively small compared to the injection speed. Mathematical modeling and computer simulations based on Doi s molecular theory for the motion of rigid rods were recently used in an attempt to predict the orientation and flow behavior of TLCPs in the mold as a function of processing conditions. A reasonably good agreement between the simulation and the experiment was reported [88]. 

Earlier we mentioned that a model exists for injection-molding simulation that allows simulation to be carried out in reasonable time on relatively inexpensive computers. This model is based on the fact that in a thin-walled part we may neglect any pressure variation in the normal direction. This assumption underlies the basis of most commercial plastic CAE analysis. 

TMcmicept, Injection molding simulation software system. Plastics Computer Inc. 

Ke Twords computer aided engineering (CAE), computer simulation, fiber orientation prediction, fiber orientation modelling, fiber reinforced thermoplastics, finite difference method, finite element method (FEM), flow, glass fiber reinforcement, injection molding, mold filling analysis, warpage. 

Bergan PG, Felippa CA (1985) A triangular membrane element with rotational degrees of freedom. Comput Meth in Appl Mech Eng 50 25-69 Berger JL, Gogos CG (1973) A Numerical simulation of the cavity filling process with PVC in injection molding. Polym Eng Sci 13 102-112... 

Fan Z, Friedl C, Costa FS, Jin X (2010d) Three-dimensional anisotropic thermoviscoelastic simulation of residual stresses in injection moldings of thermoplastics. Proc 9th World Congr Comput Mech, Sydney (Abstract, p 69)... 

Fan Z, Iwamura C, Xu S, Costa FS, Supiamaniam Y (2006) Reducing the computation time for three-dimensional simulation of warpage of injection molded plastic parts. Proc 7th World Congr. Comput. Mech. Los Angeles, CA (Abstract p 343)... 

Pig. 6. Filling of a double-gated injection mold with polypropylene, (a) Experiment using a series of short shots and (b) simulation. -I-I-I-I-I-I—I- = Computed weld line. Reproduced from Ref. 28. Courtesy of Elsevier Science Publishers. 

Gotzmann et al. [12] of Bayer Plastics discussed the manufacture of metal-plastic hydride components, including injection molding plastics such as glass fiber-reinforced polyamides around a steel aluminum profile placed in the mold. Some applications of such components were examined, and computer-aided material selection, finite element analysis, and computer simulation systems developed for use in this technology are described. 

NatureWorks s injection moldable grade of Ingeo in the capillary rheometer test has shown a good fit into the Cross-WLF viscosity model (see Table 6.2). There are seven coefficients in the model and it is readily embedded into Moldflow software for injection molding simulation (Moldflow Plastic Labs 2007). Moldflow is computer software that is widely used across the plastic injection molding industry to predict and optimize the... 

In certain cases it will be necessary to provide for preliminary experiments. Programs for the computer-aided simulation of the micro-injection molding can be helpful in the early stages of part development and mold design. Under certain circumstances, such programs are overwhelmed by the size of the parts or structures. The programs available on the market should therefore be subjected to a detailed evaluation and testing phase. 

The system boundary method was formulated early on [1 ] and provides a manual calculation of a temperature control system for injection molds. The method includes the basics for the specification of the temperature control system from a practical standpoint. Simplified assumptions are made because a three-dimensional simulation of complex molded part and channel geometries is not possible. Nevertheless, the method is suitable for the thermal design of injection molds and is based on accurate physical relationships. Simple tools/mold geometries can be exactly calculated with the system boundary method. For more complex molds, simplified assumptions are made, or more system boundaries are calculated and then combined. The advantage of the system boundary method is its simple and quick application with sufficient accuracy (which can be achieved through a continuous development of a computer program), the extensive material data collection, and a simplified and clear presentation of the results [12],... 

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