To support the rapid production of large wind turbine blade models, a Netherlands-based company recently turned to computer-aided designs and CNC-machined RenPaste® 4503R/Ren® 4503H seamless modeling paste. The materials/technology combination minimized labor costs and reduced production time by 20% compared with conventional modeling methods.
Vostermans Tooling and Prototyping BV selected RenPaste® 4503R/Ren® 4503H seamless epoxy modeling paste from Huntsman Advanced Materials because of its suitability for producing accurate, 151 ft long blade models with a high-quality, smooth surface.
"These wind blade models had to meet a range of demanding criteria and be produced to a tight timescale," explained Rob Luijten, location manager at Vostermans. "The best time to test wind blades is in the spring. This meant that the models had to be finished, the composite molds completed, and the rotor blades produced in time for the test period 'window'."
The company found that RenPaste® 4503R/Ren® 4503H seamless epoxy modeling paste helped meet their deadline because it is well suited for the fast application and machining of the face layer on large precision models. In addition, model surfaces made with the epoxy paste exhibit good dimensional stability and a smooth finish without detectable seams, according to Vostermans. RenPaste® 4503R/Ren® 4503H epoxy paste has a Shore hardness of 60D, compressive strength of 2,100 psi, glass transition temperature of 159ºF (71ºC), and coefficient of thermal expansion of 32 x 10-6.
Blade Modeling Process
For its wind blade models, Vostermans' technicians built undersized backing structures from economical block materials. Then, RenPaste® 4503R/Ren® 4503H seamless epoxy modeling paste was machine applied to the substructures to a 0.6-0.8 in. thickness. After curing for 24 hours at room temperature, the paste was CNC-machined from CAD/CAM data to the required dimensions, holding tolerances to ±0.2 in. over the full length of the blades.
Machined surfaces required minimal secondary finishing. Simple hand polishing of the RenPaste® 4503R/Ren® 4503H epoxy paste produced the fine surface required for each model. As the final step, technicians spray-applied a sealer and then applied a layer of release agent prior to fabricating composite tools.
"The combination of RenPaste® 4503R/Ren® 4503H materials with CAD/CAM and CNC technology not only delivers benefits to our customers," adds Rob Luitjen, "it has enabled us to differentiate the services Vostermans provides from those of our competitors and also opened up new markets we were unable to service before."
