Compared to thermoset prepreg, thermoplastic prepreg is considerably easier to handle in an automated system. The tape form is stiff and "boardy" at typical ambient conditions, therefore an enclosed feed chamber with active cooling is not required. Resin transfer is not an issue, but component wear is, so hard surface finishes are required on contact parts such as guide chutes. All tape guidance systems maintain close geometric tolerances to the prepreg cross section to control accurate tape placement, but the stiff tape does not buckle easily, so it may pass through an air gap between head components without difficulty. All critical components are highly modular to allow rapid change-out for scheduled maintenance. Our patented HGT is used to reduce the resin matrix viscosity at the nip point of the compaction roller and substrate. This heat energy does not serve to cure the resin system, only to reduce viscosity to allow consistent starts and high quality consolidation. The temperature is closely monitored and controlled to assure optimum consolidation.
This rapid automated process produces parts with low residual stresses (particularly important in very thick parts) and eliminates post-processing and the use of expensive consumables. The structures produced using this in-situ consolidation tape placement process are high quality, well consolidated structures which have low void content, an excellent finish, superior fiber concentricity, and minimal fiber buckling. The process also allows tape to be placed in any orientation from 0 degrees (axial reinforcement) to 90 degrees (hoop / circumferential reinforcement). This capability, unavailable in many other conventional methods of automated composite processing, allows stiffness and strength to be optimized for each application, thereby minimizing structural weight and cost.
In some cases, the automation of a thermoplastic preform may be the requirement. The Customer's previously qualified autoclave process, highly complex geometries, qualified tooling that is not well suited for fiber placement or the need for unconsolidated subcomponents might dictate that the in-situ consolidation process is not appropriate. We offer high speed thermoplastic preforming technology in single tape placement and multi-tape, individual tow control configurations. Hot gas heating is still employed, but a conformable roller is utilized and the process rate is typically increased to a level that full consolidation is not realized for a given heat energy input. The resulting preform is welded together and highly stable, ready for a traditional post process, such as autoclave consolidation.
Thermoplastic composites are replacing traditional metal and thermoset composite components. They are being used for secondary structure in aerospace, as well as in a growing number of applications in industries such as defense, fluid transfer, down-hole, automotive, and many others.