Improvement of the reinforcing fiber feed node for 3D printing of composite-reinforced products

Abstract

The use of parts produced by additive manufacturing, including FDM/FFF 3D printing, is becoming increasingly widespread. In the aviation and aerospace industries, the advantages of additive manufacturing include the ability for cost-effective iterative development, the use of COST technologies, and the use of materials that can significantly reduce the cost of products. Additionally, FDM/FFF 3D printing can be used both for prototyping and for producing final products directly.

A popular and effective type of production is 3D printing with reinforcement of parts with long or continuous composite fibers. Among the many reinforcement methods listed in [3] and [4], significant types include extrusion of a prepreg and double extrusion. Prepreg extrusion involves 3D printing with a pre-formed filament, which is a bundle of reinforcing fibers inside a polymer rod. This type of printing is the simplest to implement, as it does not require a separate nozzle for the reinforcing material and can use standard nozzles and extruders for FDM/FFF 3D printing. However, the composition and percentage of reinforcing fibers are fixed, and reinforcement occurs throughout the volume of the part. Double extrusion allows for the addition of reinforcement separately from the main printing material but requires an additional nozzle for the reinforcing material and a mechanism for moving the reinforcing nozzle relative to the main one. These methods provide high control over the process and the final characteristics of the product and material, as they allow separate control over the properties and printing modes of both the main material and the reinforcing material. The main reinforcing materials are carbon fiber, glass fiber, and organic fiber such as Kevlar.

However, the more precise selection of materials and control of characteristics is complicated by impurities of unknown composition added to the reinforcing fiber during its production. The presence of such impurities complicates the study of the influence of the reinforcing material on the final properties of the products obtained. These impurities increase the stiffness of the reinforcing fiber to reduce its deformation before laying, and change its adhesion parameters to the main material. The use of raw, unprepared fiber can be complicated by problems with its feed to the reinforcing device, and there is a lack of research on this issue in open sources.