RENPASTE® CUTS WIND BLADE PATTERN PRODUCTION TIME FROM CAD DATA TO FINISHED PATTERN IN JUST 21 DAYS NOW POSSIBLE
30 November 2003 - Huntsman Advanced Materials

Using CAD-based data, wind blades of virtually any size can be made, either as a single section or by combining a number of individual sections. Determination of this will often depend on the size of the available milling machine.

RenPaste SMP is used for the top layer of the pattern - the critical surface that will define the dimensions and surface quality of the mould tool, and then the final composite part.

This material is durable enough to withstand a number of sequential mouldings, and in the future it is likely that moulds will be manufactured directly using the same RenPaste SMP process.

The RenPaste SMP layer can be applied either manually or using CNC controlled
equipment, such as the milling machine, to a backing structure made from low cost foam blocks that have been milled by CNC to the required dimensions.

The backing structure is a key component of the pattern construction and has to be
designed to take account of requirements such as the dimensional performance of the pattern under the service conditions it will encounter.

Backing structures are usually a version of the classic combination of a rigid box section topped with a sandwich of lightweight foam between epoxy glass laminates, in various combinations.

CNC extrusion of the RenPaste SMP system gives an almost entirely void-free layer, and can be applied precisely to the right thickness. The SMP layer thickness can be varied, but a depth of between 7 and 15mm provides the best balance of cost efficiency and performance.

After application of the RenPaste SMP the pattern assembly is allowed to cure at room temperature for one day. Depending on subsequent processes, the pattern may also be post cured at 40 to 60°C as a further conditioning step to optimise dimensional performance at elevated temperatures.

After curing, the SMP layer is milled to its final dimensions. The milling is controlled by the original CAD model data so ensuring an extremely accurate result. Working in this way, as little as 3mm of SMP has to be cut away, so minimising machine time and waste. The final step in the preparation of the pattern is light sanding which imparts a fine finish.

This whole production process of wind blade patterns, centred around RenPaste SMP, can now be completed in just three weeks, several weeks faster than by other manufacturing routes.

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