• Martin, Gilles Saint
• Devos, P.
• Schmidt, Fabrice M.
• Levaillant, Christophe

Abstract

This study is a collaboration between Technofan, Microturbo, Liebherr Aerospace, CROMeP and LGMT. It is a four years project focused on the optimization of the injection molding process, applied to short fiber reinforced polymers, in order to work on :-The mechanical properties improvement of the molded parts ;-The reduction and the reinforcement of parts structural defects ;-The prediction of mechanical properties. The aeronautic sector generalizes its policy of aluminum's substitution by reinforced polymers. The main advantages of these materials are a low cost and a low mass. Our study focuses on the Ultem  2300-1000 polyetherimide resin from General Electric Plastics. The injection molding process allows to realize very complex shapes in one step, but can also generates some important defects. The main defects studied in this paper are weldlines and voids. First, we present a detailed characterization of these defects which includes weldlines, meldlines and voids in thick zones. Then, we present the results of some experiment series realized in order to clarify the dependence between the defects and the injection molding process. A reinforcement of the meldlines has been obtained by modifying the symmetry of the mold cavity. This effect is simulated with Moldflow  software, and a quantitative comparison is achieved between experimental and numerical fiber orientation. Then, we apply different non-destructive control methods (like ultrasonic controls or density measurements) in order to retain the most relevant ones for the detection of voids and for their application in the aeronautic industry. Finally, we present an original process control method that can help to detect if there is a risk of void for thick parts at the very first stage of the injection molding production process.

Topics

• density
• impedance spectroscopy
• polymer
• experiment
• aluminium
• ultrasonic
• void
• injection molding
• resin