Cannon Afros (Caronno Pertusella, Italy) says that it is launching CRESIM, a pilot project to develop carbon fiber composite structures manufactured from recycled carbon fiber using a new high-speed injection process. Cannon says the CRESIM project aims to show how lightweight composites, mainly recycled from cars and aerospace parts, can be suitable for use in automotive, public transportation vehicles and sports and leisure equipment using a cost-saving technology for reimpregnation and a very fast demolding.
The 36-month, €2 million project focuses on development of ESTRIM (Epoxy Structural Reaction Injection Molding), which uses a new fast-reacting epoxy resin matrix combined with carbon fiber reinforcement handling systems, dedicated preformers, a high-pressure dosing unit, multi-component mixing heads with different injection and distribution methods, polymerization presses and relevant handling systems of preforms and molded parts. ESTRIM, Cannon Afros says, can reduce molding and cure time from 30 minutes in a traditional resin transfer molding (RTM) process to about 3 minutes.
ESTRIM offers three injection methods:
- Inject the resin with variable output, adjusting injection by reading the internal pressure in the molds with a series of pressure sensors. The signal is sent to the controller, which defines the new output value to be applied and adjusts the dosing pumps accordingly.
- Apply the injection-compression method; leave the mold partially open during injection and applying final compression at the end of injection.
- Inject the resin and apply a low clamping force on the mold, which will tend to open during the liquid-filling phase. At the end of injection, apply the full nominal clamping pressure and compress the mold.
Further, Cannon Afros reports that it has developed two alternative methods for the impregnation of carbon fiber mats, both to be applied in open mold prior to the closing of the press:
- ESTRIM SL (spray laydown). The epoxy formulation is sprayed by robot directly over the carbon reinforcement, covering each square centimeter of the mold with extreme precision.
This technique allows for the use of viscous formulations, characterized by low flowability, and of mats of recycled carbon fibers. The resin, being directly deposited in-situ, does not need to flow through the fibers, avoiding any distribution problem into the mold and the shifting of the fibers during flow of the liquid resin.
- ESTRIM LL (liquid laydown). The epoxy formulation is laid over the carbon mat in “liquid ribbons” of varying width, typically from 40 to 120 mm (1.6 to 4.7 inches), impregnating the reinforcement with minimum air inclusions. This technique allows for the production of very large parts, wetting uniformly the huge, almost flat preforms that characterize parts such as roofs, engine hoods, fenders and doors. Because the reactivity of the systems is controllable on a part-to-part basis, Cannon says this system allows for a comfortable laydown time even for the largest pieces.
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