Dynamic mechanical properties of parts from multicavity injection mould

Purpose: The examination of dynamic mechanical properties of injection moulded parts, obtained from different cavities of injection mould, was the purpose of this research. The parts were manufactured from polypropylene. Design/methodology/approach: The testing method used was DMTA - "Dynamic Mechanical Thermal Analysis" - which is often used to determine the properties of polymers, blends and composites as well as the manufactured parts. Findings: The differences in storage modulus E' and loss factor tan delta of parts from particular mould cavities were found. The differences are caused by polymer flow and thermal conditions specific for each cavity. Research limitations/implications: An injection mould with geometrically balanced runners was used for investigation. The differences in parts' properties occur for every injection mould, but they are dependent on the cavities layout and runners configuration. Practical implications: The results of investigation provided the information that there are significant differences in parts' properties. Knowing that, the mould designers should take an effort to minimize the temperature differences in the mould and to assure the equal cavity filling. Originality/value: Usually the naturally balanced runners were supposed to assure the equal filling for all the cavities. Lately some research was made which discovered that this is not true. There were some solutions of this problem proposed. All investigation was focused on simultaneous plastic flow into all cavities, but there were no investigation of parts' properties.