JEC COMPOSITES MAGAZINE - Issue #36 - October 2007 - 64

KNOW-HOW Process g…/… An advanced out-of-autoclave More information Melding as a replacement for secondary bonding A combination of melting, welding and/or bonding of uncured components, melding is an alternative joining method to adhesive bonding and mechanical fastening. Melding is reported to overcome the limitations of ad-hesives by retaining a chemically active surface to react and form a bonded joint. Surfaces are left uncured or partially cured so that chemical cross-linking can occur between joined surfaces to create a structure without secondary adhesive bonds that are prone to failure. Using the Quickstep process, hot fluid cures designated Fig. a: areas of a laminate, and cold fluid prevents cure in areas to be joined later Steps of the Quickstep (figure a). Partially cured regions to be bonded are brought together in a Melding desired arrangement and the cure is completed, creating a seamless join. Process cycles, offers significantly lower capital, tooling, and operational expenses. A rapid and robust composite tube manufacturing process has been developed, which has shifted the rate-limiting step to the lay-up process. The tool contains inlet and outlet connections for the HTF which heat up the laminate from the inner surface. Rapid , heating and cooling have yielded a fully cured carbon/epoxy prepreg-based tube within 14 min. superior performance characteristics, this process is competitive on cost with generic production methodologies like vacuum bag and liquid infusion techniques. Further cost advantages are: lower investments and non-recurring cost to ease innovation processes in the products and lower tooling costs (fewer rate tools, lower initial tooling cost, use of thin composite tools, low-pressure manu-facturing). Lower energy consumption (up to 80% less than autoclave) makes the process environment friendly. A reduction in assembly/joints through the innovative melding technique and the ability to use lighter-weight cores in sandwich structures are additional advantages. The technology is currently being evaluated by a number of companies to qualify it for use within the aerospace industry. References Potential for resin infusion technology Replacement of oven curing for liquid-resin-infused preforms is another potential application of the Quickstep process. By using current preform manufacturing technologies and modified tooling (light, thin walled) it is possible to cure infused preforms under the trays containing heat transfer fluid. Cost-competitive preform-LCM and efficient Quickstep processing can provide enormous savings on final component cost. Due to positive control over curing temperature, resin viscosity can be reduced to the minimum possible level, which assists fast infusion and complete wet-out. Furthermore, it is possible to reduce or eliminate the typical risk of exothermic reaction of such resin systems. [1] V. Coenen, M. Hatrick, H. Law, D. Brosius, A. Nesbitt and D. Bond, A Feasibility Study of Quickstep Processing of an Aerospace Composite Material, SAMPE Europe Conference, Paris, France (2005). [2] Z. Zhang and B.L. Fox BL, Manufacturing Process Effects on the ModeI Interlaminar Fracture Toughness and Nanocreep Properties of CFRP, SAMPE Europe Conference, Paris, France (2005). [3] M. Kaiser, C. Garschke, B. Fox, C. Weimer, K. Drechser, Out of autoclave manufacture of structural aerospace composite materials. SAMPE Europe Conference, Paris, France (2007). Conclusion The Quickstep process achieves superior performance with significantly quicker cycle times at far lower pressures and with less labour than alternative autoclave production systems. Despite the Contact: jschlimbach@quickstep.com.au dbrosius@quickstep.com.au More information: www.quickstep.com.au JEC Composites Magazine / No36 October - November 2007

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JEC COMPOSITES MAGAZINE - Issue #36 - October 2007

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #36 - October 2007