As a consequence of the ability to stop the cure reaction at any point in the cure cycle it is now possible to recommence the cycle and meld one part to another part to create larger parts. These larger parts can then be melded to form components without secondary bonds. Melding is a combination of melting and welding, so that one part melts into and becomes an integrated part of another part with no physical difference or separating surface remaining between them. MELTING + WELDING = MELDING Melding, like welding, melts the surface of one part into the surface of the other, thus destroying the prior existing surfaces, making one integrated whole. Unlike welding, this process does not occur over one thin weld line concentrating the forces, but can occur over a large area of a part, avoiding stress concentrations.
Melding works by precisely controlling the temperature of the fluids and the time of their application to the part as well as the area of contact. To our knowledge, this accurate temperature control is not practical with autoclave technology.
PARTIALLY CURED AND UNCURED SECTIONS
By using the Quickstep™ Melding Process a section of the part can be fully cured while another section can be left partially cured, or uncured. The joint in the Quickstep Melding Process is made with the partially cured, or uncured sections. The partially cured, or uncured sections are then laid together and cured simultaneously, as shown in the schematic below. A layer of pre-preg can be used to cover the joint between the two sections thus melting and chemically bonding with the part and mechanically bridging the joint with fibres. In addition an adhesive layer can be used between the new pre-preg and the partially cured materials of the joint to increase the peel resistance of the interface ply. For a look at the construction of a melded stiffened panel [click here].
NO FASTENERS, ADHESIVES OR STACKING TOLERANCES
The Quickstep™ Melding Process requires no fasteners, adhesives, or stacking tolerances. One component is melted and formed into another without gaps. If a part is slightly distorted or misaligned the two sections can be melded together accurately. This is possible because the uncured sections allow movement, whilst the critical areas of the part are accurately positioned with a jig.
As a consequence of utilising the Quickstep™ Melding Process the part bond/joint regions do not need to be manufactured to such tight tolerances. If there is a larger gap between parts than expected, pre-preg can be used to bridge the gap. Alternatively, the uncured bond region will 'take-up' the gap. There should be no weight increase in this technique as what is added on one side is removed from the other side.
NO SECONDARY BONDS
The Quickstep™ Melding Process results in no 'Secondary Bonds', as all bonds are 'Melded' to provide mechanical plus molecular bonding with enhanced inter-laminar shear that is as good as any other section of the laminate.
Without fasteners, a structure manufactured utilising the Quickstep™ Melding Process can be designed only for the service loads that it has to carry. The part thickness does not need to be designed to take bolts at the fastening points. With a fully integrated melded structure, the part and overall structure will only be designed for the service loads imposed on it. The load paths could flow from one part to another without stress concentration points at fastener locations. The possible total weight and cost savings could be significant and these are obviously dependent on the size and amount of integration required of the part.