Emerging composite molding process

Until recently, resin film infusion (RFI) was not widely used. But now there are signs that this method has been added to the mainstream of composite molding technology. It has been commercially applied in the automotive, marine, aerospace and other fields.
Molding principle The RFI molding process is sensible and simple. It is based on the following design philosophy:
If the resin is applied to one side of the dry fiber ply or preform and then allowed to penetrate the entire thickness of the material to the other side, the path of the resin through the fiber must be short in order to achieve a rapid and complete soak. Process engineers found that if the resin film is used as a raw material, it is heated and melted, and vacuum or pressure is used to assist the fiber to penetrate the fiber. This can be achieved. As a result, the RF1 process was created.
Process Overview A pre-catalyzed resin film is placed in a mold and covered with a dry reinforcement material. Seal the mold cavity with a sealed, positioned vacuum bag. Then use an oven to heat and melt the resin. The resin penetrates the fiber layer under vacuum and solidifies. For a thick cloth layer, a semi-rigid resin film with a separate system may be inserted between the cloth layers. This method is also more flexible and is not limited to the use of vacuum bags, pressure bags or even molds. In cases where higher fiber content and degree of cure are required, autoclaves can also be used instead of boxes.
Advantages The RFI process offers significant advantages over existing molding techniques. In a resin transfer molding (RTM) or vacuum assisted resin transfer molding (VARTM) process, the liquid resin is passed through a fiber preform in a mold by pushing or suctioning to form the final article shape. These methods expose the resin to longer, sometimes even more complicated, paths. In order to ensure uniform advancement of the front resin, leaving no pores or dry areas, careful process design and detailed considerations are required. The scrap rate may be high (at least in the early stages). These methods require the use of counters, which increases the cost of mold making. The molding manufacturer must mix the resin, add the appropriate amount of curing agent and catalyst, and the amount must be compatible with the fiber and mold type. If you do not keep the same, it will lead to uneven product quality.
The RFI process overcomes these shortcomings. Heating and vacuum (or pressure) help the resin penetrate the continuous fiber preform so that the resin is distributed evenly and the product molding cycle is short. Using a vacuum bag to form a low pressure on the other side without the resin film can achieve the effect of trapping the emissions of the closed mold system without using a slot of the counter-mold. The resin material is supplied in a controlled form, which already contains a suitable amount of curing agent and catalyst. They act after heating and cure after the fiber reinforcement is completely ooze.
The RFl process also has advantages over the molding process using a resin premixed fabric (resin can also be controlled). Premixes often rely on high temperatures and curing pressures to achieve effective penetration and cure to eliminate porosity. Therefore, a pressurized oven or autoclave must be used. Although thermo-compression molding of prepregs can achieve high fiber volume fractions and quality products, engineers are increasingly eager to find alternatives that are less costly. RFI is a viable option.
In summary, the main advantage of the RFl process is its ability to impregnate a super-thick fiber layer at a time. With a high degree of three-dimensional. Structure stitching, woven prefabrication can be soaked, and core materials that can withstand the process conditions can be molded together. Users are looking for ways to accurately obtain high fiber content and minimize the formation of defects due to the pores and zones. The RFI process seems to meet these requirements.