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             afp/atL design-to-manufacture:

             THe GAP    by jeff sloan

             managing                   Automated fiber placement (AFP) and auto-
                                        mated tape laying (ATL) advances over the
                                                                                       ated via finite element analysis (FEA). In an
                                                                                       ideal world of 100 percent data portability,
       production of                    past decade have enabled The Boeing Co.        that CAD application would not only sup-
                                        (Seattle, Wash.), Airbus (Toulouse, France),   port design with composite materials but
          a structure                   and a growing number of other aircraft         also would “know” the capabilities of all
                                        OEMs and tier suppliers, for the first time,   AFP/ATL systems as well as all of the physi-
     made via fiber or                  to manufacture large commercial aircraft       cal limits of fiber tow and tape when it’s
                                        structures almost entirely of carbon fiber     placed on convex or concave surfaces. All
      tape pLacement                    composites. And the speed, accuracy and        of this knowledge would be incorporated
       often requires                   efficiency with which today’s AFP and ATL
                                        equipment can lay down carbon fiber mate-
                                                                                       automatically into the design by the CAD
                                                                                       system, thus preventing the designer from
      software-aided                    rial holds much promise for volume applica-
                                        tions outside the aerospace market.
                                                                                       unwittingly creating a product or structure
                                                                                       that violates principles of manufacturabil-
         manipuLation                      Although AFP and ATL speed and efficien-    ity. This pristine CAD data then would be
                                        cy owe much to advances in tape/fiber heads,   handed off to a second software package
        of the subtLe                   robotics and other mechanical equipment,       that would convert the design information
                                        the programming and control software that      to programming code, which would feed
          differences                   drives the systems is of vital importance      the control software of the AFP/ATL system.
                                        because it forms the design/manufacturing      Primarily the province of AFP/ATL machin-
         between that                   interface, bridging the gap between the part   ery makers today, this offline programming
     which is designed                  as designed and the part the AFP/ATL pro-
                                        cess actually can manufacture. Further, pro-
                                                                                       software, in the ideal world, would under-
                                                                                       stand and cater to the AFP/ATL equipment.
              and that                  duction engineers rely on this software to
                                        anticipate and manage a host of variables in
                                                                                       It would know the physical limits of the
                                                                                       placement head on the AFP/ATL machinery,
         which can be                   what have become, arguably, the most so-       it would know what type of material was be-
                                        phisticated and challenging manufacturing      ing placed (tape or tows), and it would know
       manufactured.                    processes in the composites industry.          the maximum radii of that material. In this
                                                                                       way, a design would pass from the designer
                                        Offline programming 101                        all the way through FEA, programming and
                                        The finished components that emerge from       machine control with little or no human in-
                                        ATL and AFP processes begin life in the CAD    tervention necessary to clean up the data,
                                        environment, where designs are created,        enabling it to move from software platform
                                        tweaked and then, in many cases, evalu-        to software platform.

42   |   high-performance composites
   In the real world, however, there is no such   the design for the machine to account for         “and the integration of design and program-
thing as complete data portability. “From a       machinery and material limitations. This          ming will continue to evolve over the next
customer point of view, they’d like the data      disparity between ideal and real has given        several years.” In the meantime, design for
path to be seamless,” says John Melilli, vice     rise to offline programming or computer-          manufacturability will remain a significant
president of AFP/ATL machinery maker Ac-          aided manufacturing (CAM) software that           challenge. “This is not just a software issue,”
cudyne Systems Inc. (Newark, Del.). “But I        can help the user verify design integrity and     he explains, noting that the user, therefore,
don’t think that model really exists.” Most       then integrate machine, tool and material         can’t be expected to understand enough
CAD systems, though somewhat compos-              data into the manufacturing process.              about tooling, machine capabilities, materi-
ites-aware, are not attuned to the limits and        “One of the most important capabilities        als and path programming to meet the chal-
capabilities of all AFP/ATL systems. It is pos-   of CAM software,” says Jay Hissett, engi-         lenge alone. “Generally, getting the fiber
sible, if not probable, that designs emerging     neering manager at AFP/ATL machine sup-           placement machine supplier involved early
from the mind of the designer are, in some        plier MAG Cincinnati (Hebron, Ky.), “is to        in the design process is a very good idea.”
way, not manufacturable via AFP/ATL. For          produce manufacturing and productivity as-
example, what might have seemed to the            sessment. Software must help show the pro-        Ply zones and postprocessing
designer like a relatively simple placement       grammer where limits in capabilities are.”        At the heart of this data disconnect are fun-
of fiber tapes over a contoured surface in           James Mondo, president of AFP/ATL sys-         damental limits, both to what a CAD system
the CAD environment can become, in the            tem manufacturer Automated Dynamics               can know about a given AFP/ATL system and
ATL production environment, a difficult           (Schenectady, N.Y.), says the complexity of       to the fiber path data it can provide for the
or impossible geometry to construct. This         fiber placement poses a special challenge         programming of a machine. Most design
CAD system insensitivity to AFP/ATL com-          for the composites industry. “The industry is     environments do not have the capabil-
plexities means that the user must adapt          still in its infancy in some regards,” he says,   ity to consider path placement details.

                                                                                                                                                   source: cgtech

                                                                                                          Layup simulations
                                                                                                          these screenshots, taken from
                                                                                                          cgtech’s vericut compos-
                                                                                                          ite simulation (vcs), show an
                                                                                                          electroimpact product cell with
                                                                                                          two automated fiber placement
                                                                                                          (afp) heads (large photo) and
                                                                                                          (in the inset, at left) several layers
                                                                                                          of composite material that have
                                                                                                          been placed for a wing panel on
                                                                                                          which sections in red indicate
                                                                                                          errors that have been detected
                                                                                                          by the simulation software.

                                                                                                                                    m ay 2 0 0 9          |         43

“Now, data from the design group includes        software must evolve to integrate more data
aero surface information, thicknesses, stack     regarding fiber path engineering.”
orientations, sequences and design guide-           Accudyne’s Melilli sees this coming, but
lines,” says Olivier Guillermin, director of     in the meantime, he says, machinery sup-
product and market strategy at software          pliers are left with the job of making sure
source VISTAGY Inc. (Waltham, Mass.).            the design is converted to a form that can
“These designs are typically ‘zone-based,’       be managed by the machine control system.
with properties associated with each de-         The programming software provides this
sign.” These design data are usually hand-       via a function called postprocessing, where     Perfecting paths
ed over to programmers, who assess it for        path data is output as NC code for use by
manufacturability. “Data planning will occur     the control system. “Our Siemens-based          a layup sequence for a spar as programmed
                                                                                                 in cgtech’s vericut software. it reads the
here,” says Guillermin. “The trajectory of the   control system doesn’t know how to config-
                                                                                                 cad surface and ply-boundary data and adds
machine head and other factors will be con-      ure paths,” notes Melilli, “and neither does
                                                                                                 material to fill the plies, according to user-
sidered with the design. They will discover      the CAD program. Therefore, every machine       specified requirements. then layup paths are
some aspects of the design are not possible      maker must provide a ‘post’ — program-          linked to form specific layup sequences and,
and hand it back to the design team.”            ming software that provides path data for       finally, are output as machine code.
   VISTAGY’s FiberSIM fills the gap between      the machine controller.”
the CAD system and the programming soft-            Path data calculations have to consider
ware and provides the automated fiber de-        material type (carbon fiber tape or tows),      programming tool reveals such inconsisten-
position design capability that is typically     width of tape, number of tows, strain of        cies before machines begin to operate.
missing from the CAD program. At the mid-        tape/tows over surface of part, buckling po-       One of the largest limiting factors, accord-
point in the data flow, FiberSIM “sees” some     tential of tape/tows at certain radii as well   ing to MAG’s Hissett, is the placement head.
of the inequities. “Offline programming soft-    as part contours and gaps between paths.        “Software always chases machine head ca-
ware has a level of detail that cannot be di-    In many cases, the CAD software either un-      pability.” For that reason, most AFP/ATL
gested by design software,” says Guillermin,     derestimates or overestimates the ability of    suppliers also provide some degree of man-
noting that in future developments, “design      the material to conform to a given path. The    ufacturing simulation prior to actual manu-

44   |   high-performance composites
                                          source: cgtech
                                                           arena: CGTech (Irvine, Calif.), which has     core strength for the latter. He believes that
                                                           adapted its VERICUT metal machining soft-     specialists like CGTech can provide greater
                                                           ware for tape and fiber placement; and Mak-   software expertise, pointing out that some
                                                           idea (Prilep, Macedonia), which is about to   machinery suppliers — one is MTorres (Tor-
                                                           release its Mikroplace package.               res de Elorz, Spain) — recognize this and
                                                              Bill Hasenjaeger, product marketing man-   have been cooperating with CGTech.
                                                           ager at CGTech, says his company got in-         Like others in the industry, Hasenjaeger
                                                           volved in composites in 2004 when it was      notes that, generally speaking, data coming
                                                           approached by The Boeing Co. to develop       out of CAD systems is insufficient for imme-
facturing; simulation software constructs a                programming software for the ElectroIm-       diate programming use. “This is a particular
virtual demonstration that allows the user                 pact (Mukilteo, Wash.) AFP that now pro-      problem with fiber placement because of
to watch, on screen, as the placement head                 duces the forward fuselage section for the    ply boundaries, ply paths [and] courses in-
lays down material. “Simulation makes sure                 Boeing 787 Dreamliner at Spirit AeroSystems   side boundary curves projected to the tool
you can actually do all movements before                   Inc. (Wichita, Kan.). Boeing knew that in-    surface,” he contends. “The programming
you go out to the machine,” notes Melilli.                 ternal teams and contract vendors would       system must be ‘tolerant,’ and you want to
                                                           use multiple AFP/ATL machine types in 787     avoid forcing the customer to clean up data.
M a c hi n e i ndependence                                 production and wanted machine-indepen-        It’s not hard work, but really tedious.” He
Although programming software tradition-                   dent programming and control software on      notes that CAD export, path generation in
ally has been the responsibility of AFP/ATL                which all the machines could standardize.     VERICUT, postprocessing and simulation of
machinery manufacturers, there is a move-                  Developed in 2005 for the ElectroImpact       787 fuselage Section 41 at Spirit took one
ment afoot in the composites industry to de-               machine, CGTech’s VERICUT ATL/AFP soft-       person four days to accomplish. “People
velop programming software independent of                  ware today can be customized to work with     are trying to lay up way more complicated
machine type. This means that a user is not                anyone’s system. Hasenjaeger contends         shapes than have ever been tried before.”
bound to the programming software sold                     that despite the proprietary status accord-      In beta testing as of this writing, Makidea’s
with the machine. Currently, two companies                 ed to programming software by machinery       Mikroplace was written for use with a new
are working in the machine-independent                     suppliers, software development is not a      AFP machine from sister company Mik-

                                                                                                                                     m ay 2 0 0 9   |   45

rosam (Prilep, Macedonia, see the review in       optimizations to increase throughput. “We     assertion that programming for AFP/ATL
“New Products,” p. 48), but Makidea’s presi-      have also successfully done analytics to      will evolve completely to the independent
dent, Samoil Samak, says the software’s           show steering violations, based on machine    model, as it did in the machine tool indus-
modular construction can accommodate              limits and roller bending beyond the abili-   try. “The machine tool industry is a mature
other ATLs and AFPs. “The system is able to       ties of the fiber placement head.” The com-   industry, and the large number of machines
lay up plies using a cylindrical rosette trans-   pany also is developing a simulation tool.    made it possible for third-party software
fer type and parallel path,” he says, and it         Automated Dynamics’ Mondo has some         suppliers to penetrate the industry success-
can model kinematics of a machine, create         reservations about machine-independent        fully,” says Mondo. “There are not a lot of
a simulation of its movements and provide         software — particularly in regard to the      fiber placement machines ... by comparison,
                                                                                                so it will be some time, I believe, before
                                                                                                this will be a profitable area for third-party
                                                                                                suppliers since the volume is not there.”
                                                                                                Greater impediments will be posed, he con-
                                                                                                tends, by the more complicated nature of
                                                                                                fiber placement vs. metal removal and the
                                                                                                need to understand how the software, ma-
                                                                                                chine, composite material and tooling im-
                                                                                                pact part manufacturing. “If a customer is
                                                                                                having a problem, the equipment supplier
                                                                                                is responsible for troubleshooting,” Mondo
                                                                                                maintains. “If there is a software issue, the
                                                                                                equipment supplier is at the mercy of the
                                                                                                third-party software supplier to make the
                                                                                                necessary changes to solve the problem.”

                                                                                                A better CAD/CAM future
                                                                                                Despite the data inequities, ATL and AFP
                                                                                                are relatively young processes and there is
                                                                                                much opportunity for CAD software design-
                                                                                                ers to develop systems that are better able
                                                                                                to account for the complex variables. In fact,
                                                                                                current CAD systems already do much bet-
                                                                                                ter than their predecessors. “Composite de-
                                                                                                sign software will continue to add function-
                                                                                                ality for AFP/ATL, including new tools for
                                                                                                preliminary assessment and optimization of
                                                                                                fiber coverage,” contends VISTAGY’s Guiller-
                                                                                                min. In the arena of offline programming,
                                                                                                MAG’s Hissett says optimizing fiber and
                                                                                                tape use is a top priority. In short, the work
                                                                                                has only begun, and there is much about
                                                                                                which to be hopeful. “We now do parts that
                                                                                                five years ago we couldn’t consider,” notes
                                                                                                Mondo, but adds, “The most challenging
                                                                                                parts are the ones we haven’t seen yet.”

                                                                                                  Read this article online at
                                                                                                  Read more about AFP/ATL technology in:
                                                                                                  “ATL and AFP: Signs of evolution in machine pro-
                                                                                                  cess control,” HPC September 2008 (p. 41) or
                                                                                                  “ATL and AFP: Defining the megatrends in com-
                                                                                                  posite aerostructures,” HPC July 2008 (p. 68) or

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