This paper describes a method for obtaining the thermal contact resistance (TCR) between an injection molded part and its mold. Due to the absence of TCR the simulated cooling times obtained from Polycool II, a computer aided engineering (CAE) package for cooling simulation of injection molding, have compared poorly with both field and experimental data. This paper shows that an improvement in the accuracy of the simulated data results from making TCR an Input to Polycool II. TCR was obtained through a combination of experimental and analytical procedures. Experimental work was performed to obtain the part surface temperature distribution and the inside cavity pressure gradient. The part surface temperature distribution was then used as a boundary condition in the thermal analysis. The inside cavity pressure gradient was utilized as a basis for determining the inside cavity shrinkage. The results show that due to the thermal expansion of thermoplastics, the compressibility of the plastic melt, and the mold deformation, the inside cavity shrinkage is reduced as the thickness of the part is increased. Therefore, the TCR value of a thicker part is lower than that of a thinner part. The effects of both part thickness and process parameters, such as temperature and pressure, on TCR are also discussed.
This paper describes the development process and requirements of a multimedia engineering tutor as well as the specific development of a multimedia injection molding tutor at the University of Massachusetts Amherst. The injection molding tutor is beneficial to any user that has little or no previous knowledge of injection molding and design for injection molding.
This prototype interactive software system can help teach upper level undergraduate and graduate students in mechanical engineering fundamental concepts and offer guidelines for finite element modeling and analysis (herein referred to as FEA). In lieu of a mathematical treatment of the subject commonly found in textbooks, this FEA tutoring system employs rich animations for conveying highly visual concepts and offers the user a set of experiential modules for exploratory learning. The system has been developed initially for the domain of linear structural analysis, but it can be expanded to include other engineering analysis domains, such as vibration, heat transfer, and nonlinear finite element analysis. Initial formative testing of the tutor on junior mechanical engineering students indicates that a 45‐minute session with the tutor was at least as effective as a one‐hour introductory lecture by an FEA expeI.
This paper describes an alternative approach to the rules-of-thumb-based design of metal stampings. The design for manufacturing system (DFM) presented here highlights those manufacturing-related features that significantly increase cost so that designers can minimize difficult-to-produce features. The DFM system is not dependent on the creation of a geometric model, and can be used to qualitatively and quantitatively assess a preliminary concept sketch. The system focuses on stampings produced by “hard tooling” and is based on expertise gained from stampers who produce parts for the office automation, computer, electromechanical, and small consumer appliance industries. The application of the system to a real-life part is illustrated.
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