JEC COMPOSITES MAGAZINE - Issue #33 - June 2007 - 36

The milling tool FEATURE “Construction” g…/… The optimised non-destructive post-fitted foam sandwich insert The rotating milling tool in Figure 3 (Swedish patent, international patent pending) expands during rotation that is powered by the centrifugal force. A normal power driller ( ≤ 3,000 rpm) ensures the necessary centrifugal force, which makes it easy to use. The cutting sheath moves along the face sheet during rotation and simultaneously cuts out the optimised cavity in the core. In the end, this is the contour of the insert. The supporting bearing plate fixates the tool during use in axial and radial directions at an adjustable depth. The milling tool will thereby be usable for different face sheet thicknesses. This tool makes it possible to mill an optimised cavity in an assembled sandwich structure. The tool only needs an entry hole through the face sheets, which is substantially smaller than said cavity. The system Fig. 4: Schematic work description for the system. (1) Foam core sandwich structure. (2) Drill a hole through the face sheets with the same diameter as the milling tool. (3) Adjust the milling tool for the specific face sheet thickness. Place the milling tool in the drilled hole and attach it to a power driller. (4) Mill the cavity. (5) Clean the cavity with a vacuum cleaner. (6) Use the specific adhesive dispenser to fill the cavity with adhesive. (7) Place the female/male threaded insert in the cavity. (8) Wait for curing. The insert is ready for use. The optimised post-fitted insert system consists of the milling JEC Composites Magazine / No33 June 2007 References Fig. 5: Cut-outs of sandwich panels with mounted inserts. tool, adhesive, an adhesive dispenser and, if needed, female/male threaded inserts. The adhesive dispenser ensures that the cavity is filled with the right amount of adhesive. The adhesive should have a specific viscosity, to ensure that the air flows out of the cavity when mounting the insert. For applications without very high structural demands, it is possible to use only the cured adhesive as an insert. This system for mounting (Figure 4) an optimised nondestructive post-fitted insert is very flexible and less labour intensive than the optimised post-fitted systems used today. The fact that an optimised insert can be mounted without demounting and reassembling the face sheets, thus avoiding any loss of structural performance, makes this system beneficial. The adhesive dispenser with adjustable volume dosage for each insert size makes the mounting repeatable, which guarantees the quality of the assembled inserts. Figure 5 shows cut-outs of sandwich panels with mounted inserts. More information: www.composult.com Contact: info@composult.com [1] Shipsha A., Söderlund J., Zenkert D., “Shape Optimisation of an Internal Metal Doubler for Load Introduction in Sandwich Structures”, Proc. Sandwich Construction 4, pp. 839-851, Emas Ltd, West Midland, UK, 1998.

http://www.composult.com http://www.vonroll.com

JEC COMPOSITES MAGAZINE - Issue #33 - June 2007

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #33 - June 2007