-We go dry

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Dry Composites is an initiative by Danobat Composites to share the latest advancements in automation using dry composite material. This online community aims to connect companies, research centers, academics and experts interested in the use of dry composite material to develop structural parts in aerospace.

What do we mean by Dry Composites? There are two distinct methods of making composite structures. The first involves impregnating the fibres in a dedicated off-line machine to make a pre-impregnated material, called pre-preg. This is then transported to a factory that makes structures where it is laid up by machines or manually.

The second, more direct route is to take dry fibres, usually in some textile format and after assembly into a pre-form, infuse them with liquid resin. The infusion process is known by a number of trade names and acronyms such as RTM, VARTM etc.

The pre-preg route involves an extra process and hence cost, but it does result in structures with good consistent properties. Recently, the performance of structures made by infusing Dry Preforms has improved and is now claimed by some, to match that of more conventional pre-preg materials. Working with dry fibers, fabrics and textiles enables thicker layers to be used, saving time and labour costs, plus aiding in the creation of more complex, one-piece structures.

However whereas the pre-preg manufacturing industry is well served by automation with dedicated machine tools, the lay-up of dry fabrics has not received the same attention. Danobat Composites has pioneered the development of Automatic Tape Laying using woven and NCF fabrics. This has improved laminate quality, repeatability and reduced the cost of composite structures by significantly cutting manufacturing labour and material costs. Moreover, it is worth mentioning that the use of dry materials can give rise to out of autoclave curing processes acquiring required properties in primary structural aerospace parts.

Today, manufacturers face the challenge of doing more with less, the aerospace industry needs to adapt quickly to new material and process developments to remain competitive. In doing so, the ultimate goal of a disruptive automation technology is to introduce new processes that may deliver better high efficiencies and control at less cost. This requires broad support from an ecosystem of R&D, manufacturing, engineering teams and material developers.

Dry Composites is an open space for those interested in learning more about how automation using dry composite material can be applied to the aerospace industry. From sharing industry news, information, data and technical solutions about dry composite solutions to interviews and perspectives from expert sources. Our target audience includes decision makers, R&D engineers, global suppliers of advanced materials, software and automation companies.

If you are interested in learning more about advancements in the use of dry material in the aerospace industry, follow us on Twitter @drycomposites and join the LinkedIn Group Dry Composites.

Stay tuned for more!

4 thoughts on “-We go dry

    1. DryComposites

      Dear Dr. Sommer,

      Thanks for being interested in our post. You can find an explaination for your question below.

      After the dry preform is created, the resin is infused into the preform in one of two ways. First, the resin can be “sucked” into the preform using a process called vacuum resin infusion. A vacuum bag film is placed onto the preform and sealed to the mold. There is also a distribution media between the preform and the vacuum bag. A vacuum is pulled under the bag, and a resin supply is introduced at another location of the vacuum bag. The vacuum causes the resin to be pulled into the bag and it gradually fills the dry preform. The resin flow front moves in the plane of the preform, aided by the distribution media. The resin flow front also penetrates through the thickness of preform, completely wetting out the preform, because the porous preform presents another path for the vacuum to reach the resin, and the resin “follows” the vacuum and infuses dry material in its path.

      A more complete description can be found at http://www.vacmobiles.com/resin_infusion.html.

      Many aerospace companies have developed and patented variations of this basic process which are called by various names including VARTM (Vacuum Assisted Resin Transfer Molding) by Lockheed Martin, CAPRI (Controlled Atmospheric Pressure Resin Infusion) by Boeing, BRI (Bulk Resin Infusion) by Boeing, VAP (Vacuum Assisted Process) by Airbus, RTI (Resin Transfer Infusion) by Bombardier, etc., RFI (Resin Film Infusion), etc

      A second process is called RTM (Resin Transfer Molding). In this case the preform is placed in a closed cavity mold, and the resin is pumped into the preform under higher pressure. The advantage of RTM is that all parts surfaces are controlled by the mold, providing better dimensional control and finish. The disadvantage vs. vacuum infusion is that mold cost and equipment costs are much higher, and part size is much more limited.

      Reply
  1. craig young

    I have noticed that RTM is having a second life after it’s initial promise in the 70′s, this is mainly due to the stringent laws on emission of styreen and the auto industrie’s involment. The added cost compared to wet layup can put smaller producers off, and there lies the problem that killed it in the 70′s. People try it with cheap tooling, fail, then give up wondering what all the fuss was about. When done correctly and with good guidance then it can be a very good system, using the internet now you can get good guidance and then decide upon which system is good for you. Now we have the people to help you with that .

    Reply

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