A unique machine for the technical textiles and composite industry in our Research and Technology Center.
In a Uni-Directional laminate or UD the individual fibres are oriented parallel to each other and kept in this aligned position by a matrix material. This is realized by unwinding the roving, tow or untwisted yarn from a creel and spreading them into continuous layer of several filaments thickness. It is subsequently stretched by means of a considerable force for impregnation with the matrix material. In the case of thermoplastics, an extruder is used in combination with a calendar to guarantee thorough immersion of the fibres in the matrix. The UD is the starting material for production of a crossply laminate, but can also be used in other composite production processes like tapewinding or continuous compression moulding. A unique machine for the technical textiles and composite industry in our Research and Technology Center.
The simplest way of producing a crossply is cutting segments from the UD, stacking them in the desired orientation – normally 0/90° – and pressing them together. To transform this time consuming activity into a continuous process, Van Wees developed the Multi-axial UD Crossply machine in which splicing and lamination are combined. This means that rolls of crossply laminate can be generated in which the orientation between the continuous UD and segmented layer can be varied from 45 to 90° and from which multilayer panels can be readily assembled. The thermoplastic behaviour of the matrix material not only enables the lamination in the crossply machine and the stacking of multilayers, but also makes it possible to bring the panels into the required geometry by means of thermoforming. Naturally, the mechanical properties of the resulting continuous fibre-reinforced thermoplastic composites are superior to those based on chopped strand mats or oriented long fibres. But even in comparison with fabric reinforced composites, crossply laminates have distinct advantages. Thanks to the spreading of the fibres into a thin layer and the absence of crossing yarns, the impregnation with matrix material is much more effective. Both lead to intrinsically higher mechanical performance. Besides this, the UD-layers can be orientated in directions that are optimum for accommodating the forces in the end application. This is how the reinforcement can be made more efficient, leading to a more lightweight construction. The UD production and Multi-axial Crossply production are fast processes in comparison to weaving and impregnation. This means that high volume composite materials can be produced at competitive costs.
The development of the Multi axial UD Crossply machine for our Research and Technology Center has been made possible by means of a contribution of the European Regional Development Fund within the framework of OPZuid.