Resin injection
Introduction
The manufacturing processes of polymer matrix composite materials can be divided into two large blocks: open mold and closed mold.
Open mold manufacturing processes
Hand placement molding
hand lay-up or manual lay-up molding is so called due to the low or no pressures it requires. It is widely used in the aerospace industry due to its great flexibility.
This is a very slow process, with more than 50 individual stages. The manual placement stage of the sheets consumes around half of the total process time.
The possible defects that parts manufactured using this method may present are: wrinkles on the surface, trapped air bubbles, pores and pits, cracks and cracks, poor adhesion to the mold, sticky areas and outcropping of fibers.
Filament Winding
winding or filament winding is a manufacturing process in which continuous reinforcements are wound at high speeds and precisely on a mandrel that rotates around its axis of rotation. Working speeds are between 90 - 100 m/min for glass fibers and between 15 - 30 m/min for carbon and aramid fibers.
Through this process, fiber volumes of up to 75% can be achieved, making it possible to control the resin content. However, it is necessary that the piece be of revolution and without incoming curvatures. The shape of the piece must allow the mandrel to be removed.
There are three winding models:
This process is used to produce high strength hollow cylinders. The fiber is provided through a resin bath and is then wound onto a suitable cylinder. When enough coats have been applied, the cylinder (mandrel) is cured in an oven. Finally, the molded part is separated from the mandrel.
Applications to this process include chemical and fuel storage tanks, pressure vessels, and rocket engine casings.
Process models provide the following information as a function of position and time: