RenPaste XD 4618-1 R/H seamless modelling paste (SMP) from Huntsman Advanced Materials enables marine model makers and shipbuilders to produce almost any marine model from large hulls and decks (up to 36m in length) to highly specialist applications for racing and competition craft. Now, the material has been used in one of the marine world’s most exciting new projects, the Hydroptère ‘Flying’ Trimaran. The paste is being used by Swiss-based composite prototyping consultancy, Décision SA to form the plugs that are ultimately used in the mould production of the sailing boat’s wing floats.
Normally, marine plugs are made from traditional materials such as wood and it is a highly skilled, labour and time intensive task. However, by using RenPaste SMP combined with the latest CAD controlled milling technology, significant time and development cost savings can be achieved.
The plug design for the Hydroptère floats is broken down into a number of component parts and converted into milling data files which guide the CNC milling machine. These CAD files are transmitted from Décision to their CNC subcontractor, Imhof & Fils, who use them to machine slightly undersized polystyrene foam (EPS) cores of each plug component.
The SMP is then applied by a special mix/meter machine over the EPS cores and left to cure at room temperature. Once cured, the model is dimensionally stable and presents a solid surface that is particularly well suited to CNC milling. For the Hydroptère plug, the SMP layer is milled back in two passes (rough forming plus finishing) to produce the final surface of the plug components.
The parts are then delivered to Décision where they are sanded, finished and bonded together to form the complete plug, which is then prepared for mould production and infused under vacuum.
“We found the RenPaste XD 4618-1 delivered several benefits over other production techniques,” explains Bertrand Cardis, manager and EPFL engineer, at Décision. “It has proved much more durable than low density foam plugs and it is easy to machine, producing an exceptionally high quality surface finish. It produces dimensionally stable, highly accurate parts and has low vacuum permeability - very important for our vacuum moulding processes.”