Methods and Parameters for Design and Operation of Tempering Systems in Injection Moulds
Mould temperature control has a major impact on process economics in injection moulding. Heat removal out of the part is thereby crucial for part quality, energy efficiency and achievable cooling time. Therefore, the entire process of mould temperature control was analysed concerning possible optimisations. Potentialities for improvements were identified in the area of thermal design and in the operation of tempering systems.
Within the thermal design, quality of results can be improved most notably. This can be achieved by computer aided generation of tempering channels. Therefore, a novel concept, based on topology optimization, is suggested. Furthermore, in injection moulding simulation, major uncertainties exist concerning modelling heat transfer from polymer to mould. This leads to deviations in calculating the temperature distribution within the part and hence, to inaccuracies in computing shrinkage and warpage. Therefore, the heat transfer coefficient between polymer and mould is measured within the injection moulding cycle. For that, mean demoulding temperature is acquired by means of calorimetry and an infrared temperature sensor is utilized to measure part surface temperature. In a similar setup, the effective thermal diffusivity is determined for common thermoplastic polymers. These values enable a practice-oriented cooling time calculation. Within the experiments, the influence of selected process parameters on the heat transfer coefficient and the effective thermal diffusivity are investigated.
In the area of operation of tempering systems, potentialities for improvements exist for the degree of reproducibility of the temperature distribution in the injection mould. In addition, cooling time and energy efficiency can be improved. Therefore, opportunities for improving heat transfer in the tempering channel are investigated and evaluated. Furthermore, fundamentals for specifying the ideal flow rate of the tempering medium are discussed. Mounting principles for mould temperature sensors are outlined and the necessity of a defined workflow for the setup-procedure are pointed out.Lesen Sie die deutsche Zusammenfassung auf Kunststoffe.de
injection moulding, tempering, injection moulding simulation, heat transfer, thermal mould design, cooling time, effective thermal diffusivity, heat transfer coefficient, topology optimisation
Institute / chair: Technisch-Naturwissenschaftliche Fakultät der Johannes Kepler Universität Linz
Technical consultant for expert services: Prof. Dr.-Ing. Georg Steinbichler (Betreuer), Prof. Dr.-Ing. Dietmar Drummer
Publication year: 2015
Provider: Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK) / Kunststoffe.de
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