Cytec Industries Inc. (Woodland Park, NJ, US) launched new epoxy and bismaleimide (BMI) versions of its DForm (Deformable Composite System) fabric tooling prepreg. DForm is a prepreg format that combines short-fiber conformability with the handling and laminate characteristics of a conventional long-fiber composite. For the new epoxy and BMI versions of DForm, Cytec is manufacturing the fabric in multi-ply “tiles.” The epoxy version is available in two tile types, one with two layers of 3K carbon fiber twill and four layers of 12K carbon fiber twill; the other epoxy tile type is composed of just four layers of 12K carbon fiber twill. The BMI version is available in one tile type, composed of eight layers of 6K carbon fiber twill. Cytec says a typical tool will use two layers of tiles, with an autoclave debulk between tile layers. The tiles, Cytec points out, allow a tool to be layed up faster with fewer debulk cycles, thereby saving costs associated with labor and time. Further, Cytec officials said the material, because of its easy conformability, does not need to be laboriously pushed into female tool details. As a result, Cytec says labor savings using the new DForm tiles, compared to a traditional 10-ply epoxy layup, are about 80%. Compared to a traditional 16-ply BMI layup, labor savings are about 87%, says Cytec.
DForm deformation characteristics are achieved through selective fiber slitting of a fabric prepreg. Cytec selectively slits the material in a discrete pattern, with the slits at a 45° angle to the axis of the tape. Each slit or cut is approximately 50 mm long, effectively creating a web of discontinuous fibers. The prepreg tape retains its overall integrity and fiber alignment, but the slits allow intraply movement. When the tape is layed up, the slits open slightly, allowing stretch and conformability while good strength is maintained. Cytec notes that abutting tiles can be chamfered and reports that the material’s conformability greatly reduces the risk of bridging. DForm currently ships from Cytec’s plant in Tulsa, OK, US, and eventually will be available from its Heanor, UK, facility as well.
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