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In rotor blade production, one obvious way of accelerating the process would be to use polyurethane-based adhesives for rotor blade bonding, although these represent a very recent development in the wind power industry. Traditionally, blade shells and spars have been bonded using two-component epoxy resins. While these materials reliably meet the extremely high mechanical specifications, they are rapidly reaching their limits when it comes to the automation of manufacturing processes. New technologies are therefore needed to speed up and automate production.
Henkel is now presenting a solution in the shape of its newly developed polyurethane adhesive Macroplast UK 1340. The specialist in high-performance polyurethane adhesives has succeeded in developing a PUR adhesive that satisfies the specific mechanical requirements for use in the wind power industry and, on top of this, makes rotor blade production more efficient.
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Picture (Top): In a long-term test lasting some four months conducted by the Fraunhofer Institute for Wind Energy and Energy System Technology IWES, an ENERCON rotor blade bonded with Macroplast UK 1340 was subjected in Bremerhaven to stresses and strains that would normally occur over a period of 20 years.
(Below): The bonded joints of the 40-meter long blade passed the IWES endurance testing program involving static and dynamic tests specified in the IEC 61400-23 standard to determine the rated load and fatigue behaviour of the blade.
Higher capacity utilization through faster curing
One of the major benefits offered by Macroplast UK 1340 is its accelerated cure speed. Polyurethane-based adhesives react much faster than the epoxy resins used up to now. Since it is not only highly reactive but also produces less reaction heat, this two-component adhesive considerably reduces both the duration and the temperature of the cure phase. Extensive tests have shown that substantial reductions can be achieved in bonding and tempering times. The lower cure temperature also has a positive impact on energy consumption in addition to reducing the risk of stress cracking due to excessive thermal loading. And heat-sensitive foam inserts also remain unaffected.
What is more, Macroplast UK 1340 satisfies the high mechanical demands for this application, as confirmed in a variety of tests. The key criterion for achieving the technology shift is described by Nicole Schlingloff, product developer at Henkel who played a major role in developing this product: "One absolute essential for wind energy plants is that they have to be in technically perfect condition. Rotor blades are among the most highly stressed components one can imagine. Even the tiniest flaws can have disastrous consequences, and that can result in high costs for repairs, downtime, or even replacement of complete rotor blades. For all of those reasons, we had to make sure that Macroplast UK 1340 would entirely satisfy the market's high demands."
GL approved and IWES tested
Macroplast UK 1340 fulfills all the key parameters specified by Germanischer Lloyd (GL) and is the first PUR adhesive in the world to have obtained GL approval. GL's requirements for the adhesive primarily relate to its tensile shear strength, resistance to aging, creep behavior and glass transition. Rotor blades manufactured using Macroplast UK 1340 have already proven their worth in a field trial of more than twelve months.
Further evidence of the functional capabilities and fatigue strength of the processed adhesive was recently furnished when it successfully passed load tests performed by the Fraunhofer Institute for Wind Energy and Energy System Technology IWES. In a long-term test lasting some four months, an ENERCON rotor blade bonded with Macroplast UK 1340 was subjected in Bremerhaven to stresses and strains that would normally occur over a period of 20 years. The bonded joints of the 40-meter long blade passed the static and dynamic tests specified in the IEC 61400-23 standard to determine the rated load and fatigue behaviour of the blade. The test criteria specified for approval of wind energy plants were met without any problems. And ENERCON's own specifications were also satisfied in this blade test.
For further information, e-mail: evelyn.necker@henkel.com or view website: http://www.360bonding.com/? Refer to page 82
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Vishay Precision Group, Inc. (NYSE: VPG) offer a new training video on its Micro-Measurements website: www.micro-measurements.com Presented in HD quality, the six-minute video offers a step-by-step demonstration of the procedures and materials needed for properly bonding a WK-Series strain gage (Option W) using Micro-Measurements' M-Bond 610 adhesive. Additional videos will be released in the coming months covering a variety of related topics.
Micro-Measurements' WK-Series of fully encapsulated K-alloy gages with high-endurance leadwires offers the widest temperature range and most extreme environmental capability of any general-purpose gage. The devices feature a normal temperature range of -269°C to +290°C, and a short-term range of -269°C to +400°C. Micro-Measurements' M-Bond 610 adhesive is a high-performance epoxy resin, formulated specifically for bonding strain gages and special-purpose sensors.
The video "M-Bond 610 Adhesive Used on WK-Series Strain Gage" covers five steps in installing a WK-Series strain gage with M-Bond 610: mixing the adhesive; gage preparation and layout; adhesive application; clamping and cure requirements; and tape removal and postcure. Additional resources offered with the video include the M-Bond 610 datasheet and Instruction Bulletins B-129 and B-130, which outline the complete steps for surface preparation for strain gage bonding and for strain gage installations with M-Bond 610 adhesive, respectively.
The new training video joins three previously released videos on the website that demonstrate key procedures that are the basis for any meaningful use of a stain gage, including surface preparation, bonding, soldering leadwires, and applying a protective coating. Accompanied by additional instruction bulletins and application notes, the videos include "Strain Gage Surface Preparation for Steel and Aluminum Alloys," "CEA Strain Gage Installation With M-Bond 200 Adhesive," and "Soldering and Coating a CEA Strain Gage."
The subjects covered in the videos are also addressed in complete detail in VPG's training programs. Course descriptions and date/location information can be found on the Micro-Measurements website: www.vishaypg.com/micro-measurements/training-programs Additionally, designers may contact Micro-Measurements via e-mail: mmquestions@vishaypg.com to be connected with an applications engineer, technical sales manager, or member of the sales force regarding the subject matter covered in the videos or any other related topic.
Micro-Measurements in profile
The Micro-Measurements division of Vishay Precision Group is an industry leader in the development, manufacture, and marketing of sensors for high-precision strain measurement. Micro-Measurements offers a full complement of strain gages, data acquisition systems, PhotoStress equipment and coatings, and supplies necessary to obtain accurate, reliable stress data. Our products are used throughout the industrialized world -- both in the practice of stress analysis and as the sensing elements in a wide variety of transducers for measuring physical variables (weight, force, torque, pressure, etc.).
For further information, view website: www.micro-measurements.com
Vishay Precision Group in profile
Vishay Precision Group produces sensors based on precision resistive foil technology, and sensor-based systems. We provide vertically integrated products and solutions for multiple growing markets in the areas of stress, force, weight, pressure and current measurements. As a spin-off from Vishay Intertechnology, our decades-long track record encompasses innovations in foil precision resistors, which we invented, current sensors, and strain gages, which have served as a foundation for our more recent expansion into strain gage instrumentation, load cells and transducers, weighing modules and complete systems for process control and on-board weighing.
For further information on the Vishay Precision Group view website: www.vishaypg.com or e-mail: Marti.Spalding@vishaypg.com
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