During the injection of molten plastic material, the air contained in an injection mold must be able to escape parallel to the flow of material through vents so that the injected material can properly fill the mold cavity. If the air cannot be evacuated properly and remains in the cavity, strong compression of the air causes its temperature to rise. This phenomenon causes quality defects on injected parts, such as burns, unfilled areas, voids inside the injected plastic part, air bubbles, air frosts or even burrs (visual defects on plastic parts caused by non-optimal degassing). Inside the mold, overheating of the air in the cavity also causes a stronger migration of additives from the injected material.
This gas/air mixture, which is often aggressive, can attack the mold steel or form local deposits which, over time, block the mold's degassing channels. These problems cause non-quality costs and a loss of productivity because production must be interrupted to clean the mold in a preventive or corrective manner. Well-dimensioned degassing is an essential factor in avoiding heating of the air in the cavities and thus obtain a robust and reproducible molding process. To date, the number of studies and scientific research on the phenomenon of degassing in mussels is very limited. Plastics companies use an empirical approach without recourse to numerical simulation and experimentation.
The objective of the OptiAir project is to understand and control how the degassing of plastic injection molds works in order to increase productivity and reduce non-quality costs. A scientific basis for understanding the physics of degassing will be established by a combined theoretical approach, based on numerical modeling, and practical, based on measurements and tests.
The results of the OptiAir project will allow partner companies to acquire the skills required to validate a degassing concept already in the mold design phase, to reduce mold design iterations before it is put into production and to reduce preventive maintenance intervals for increased productivity.
The OptiAir project will start in October 2023 and end in June 2025.
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