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Advances in braiding and preforming lead composites news at SAMPE.

Advances in Braiding and Preforming Lead Composites News at SAMPE

Heading the list of recent innovations in advanced composites are developments in 3-D braiding and fiber placement processes for making stronger preforms in less time. The 35th International SAMPE Symposium and Exhibition, held during April in Anaheim, Calif., also produced its share of new materials and machines for composites. Selected details appear in the text below or in the accomanying table of new prepregs. More materials innovations from SAMPE are reported in this month's "Thermosets in the '90s" feature.


Albany International Research Co., Mansfield, Mass., has applied for parents on a new 3-D prform system for braiding multilayer interlocked tubular and flat fiber structures. The new system provides braids that are interconnected at adjacent layers and not through the entire thickness of the preform. The company's analyses suggest that this type of interlocking will enhance the interlaminar shear strength of composites without significantly reducing in-plane properties. Work is currently under way to provide experiemental confirmation.

The system also permits introduction of axial yarns, and the ratio of axial yarns to braider yarns is fully adjustable for tailoring of final composite properties. Possible applications include rocket-motor cones, damage-tolerant tubes and pressure vessels, and orthopedic implants. (CIRCLE 16)

Another sign of increasing braiding activity is a new engineering design database for braided fiberglass structural composites established by Owens-Corning Fiberglas Corp., Toledo, Ohio, and Drexel University, Philadelphia.


Advanced Process Technologies, Inc., Raleigh, N.C., is developing a proprietary, nonwoven process for depositing oriented-fiber networks at reportedly two to five times the speed of conventional weaving. The unbonded, oriented-fiber networks can be stabilized in-line by stitching, thermoplastic tacking, or thermoset sizing. They are subsequently impregnated with a matrix resin.

The process is capable of multiple orientations within a single ply and variations between neighboring plies. Combinations of fibers such as glass, carbon, ceramic, and various organic fibers can be mixed or separately deposited in a single ply.

While the process was initially developed to place fiber in two dimensions, it now appears that a ply can be deposited so that it follows the contour of a three-dimensional part. Handling of the fibers is minimal, and the deposited network is uncrimped, allowing a higher percentage of fiber strength to be retained. Controllable density is said to allow individual plies or layers as light as 15 [g/m.sup.2] and as heavy as 5 [kg/m.sup.2]. Currently, at least 90% of the fibers can be deposited in a specified direction, and maximum mat width is 0.5 meter. The company is currently considering whether to sell or license the technology, or to sell preforms. (CIRCLE 18)

The Cooper Machine Div. of Sewing Machine Exchange Inc., Chicago, introduced a near-net-shape fiber-placement machine for automated preforming. The comany says it may have applications in automotive and aerospace. The machine places fibers in accordance with information on aerial weight, fiber angles, and other parameters from a CAD system. Stitching thread attaches the fiber in a zig-zag fashion. At SAMPE, Cooper showed a four-head machine, which can make either one large preform (up to 30 x 35 in.) or up to four smaller ones at a time. Cooper plans to offer a 12-head machine in the future. The four-head unit costs around $150,000, including the CAD system. Cooper buys the machinery from a Japanese company and modifies it to suit customers' needs. (CIRCLE 19)


McClean Anderson, Inc., Milwaukee, introduced add-on equipment to ease the use of thermoplastic resins with existing filament winding machines. A new compaction roller provides constant consolidation pressure for thermoplastic as well as thermoset applications, and a new mandrel tensioning unit prevents the "whipping" effect that occurs when winding small-diameter parts that deflect. Tension is applied from both the headstock and tailstock ends, at up to 2000 lb. A new constant tow-speed control regulates material flow by controlling the time a tow is exposed to a stationary heat source.

The company also announced new mandrel slip rings that provide power for electrical equipment such as resistive element heaters that are carried along with the mandrel. The rings also serve as a signal connection for sensing devices such as thermocouples housed in the mandrel drive unit.

Finally, new outputs enable a user to switch external devices on or off based on time or position of a dependent axis within the winding program. Up to 32 external a-c/d-c devices such as clamps, heaters, and air supplies can be controlled using an ASCII RS232 protocol. (CIRCLE 20)

Heat Transfer Technologies, Inc., Sun Valley, Calif., introduced the PR filament winding nozzle, intended to eliminate the need for autoclave cosolidation of thermoplastic filament windings. The nozzle delivers two flows of temperature-controlled hot air, one to preheat the tow or tape, and the other to heat or melt the material as it touches the mandrel. It is used in conjunction with the company's microprocessor-controlled heating unit mounted on the winder carriage.

The hot air is delivered to the impingement nozzle at the payout head via a short, closely coupled, stainless-steel-insulated flex hose. Heat Transfer Technologies is currently leasing the nozzle for $75/month and may decide to sell it after patent and licensing questions are settled. (CIRCLE 21)

In other filament winding news, Electroid Co., Springfield, N.J., introduced the 2000 Series of tension-control modules for handling aramid, carbon, and glass fibers. The TCM-2000-B is a microprocessor-based passive system for limited take-back of up to 10 in. The TCM-2000-C is a microprocessor-based active system said to have virtually unlimited take-back capability. Both units contain on-board power supplies and can be connected to an IBM-compatible PC or a remote controller from Electroid. Prices range from $6000 to $8000 per tow unit. (CIRCLE 22)

There were a few lab-model filament winders introduced at the show. Engineering Technology Inc. (Entec), Salt Lake City, introduced a two-axis machine, the model PW18, for parts up to 18 in. diam. and 36 or 72 in. long. Radial, eye, and yaw axes are available as options, as are pattern-tracing software and a remote-control pendant. The machine costs from $45,000 to $100,000, depending on options. (CIRCLE 23)

Dura Wound Inc., Washougal, Wash., introduced the 11A Cobra, a two-axis helical winder capable of bi-axial wind angles from hoop to low axial. Computer software assists in selection of winding patterns, which can be implemented on the machine by manually changing the six sprockets or by optional automated digital control (up to four pattern changes).

The standard fiber delivery system on the Model 11A is for dispensing E-glass, although an optional carbon-fiber system is available. The 10-strand capacity resin bath uses the kiss-roll method to saturate the fibers on their way to an adjustable pay out eye. The machine costs $35,000. (CIRCLE 24)

Leesona Corp., sub. of John Brown Co., Burlington, N.C., introduced a new production-size winder for glass roving, heavy industrial tows, and the blending of hybrid fibers. The model 868 has a built-in programmable logic controller, and it works with a larger package size and heavier fibers than previous models. (CIRCLE 25)


For making prepregs, Research Tool Corp., Ovid, Mich., introduced the Model 40 hot-melt prepregger for broad goods of 1 x ft with 35-90% resin content by weight. The new machine has a horizontal configuration that is an improvement over the previous vertical model, according to the company. Ciba-Geigy's Plastics Div., Hawthorne, N.Y., just acquired one of the new machines for research purposes.

The new layout allows the extraction of broken fibers from the prepreg material as it emerges from the resin bath before reaching the extrusion die. The machine has three separately-controlled heating zones and a fixed die orifice. Other features include independent drum and tape traverse speeds, electronic control of speed, tension, and temperature. Options include in-line heat cleaning and coupling agent application, fiber-tension readout, video camera and monitor with 2X lens, four-spool fiber holder, vacuum shielding system, and automatic constant-tension fiber stand with digital readout. The standard model costs $60,000. (CIRCLE 26)

Quadrax Corp., Portsmouth, R.I., introduced a new exotherm reaction control system that is said to detect and prevent potentially explosive runaway reactions of resins and catalyst sooner than conventional temperature monitoring devices. Rather than measuring the absolute temperature of a resin mixture, the system profiles the rate of temperature change in the resin/catalyst mixing vessel to detect an out-of-control reaction before it can cause damage. Composites processors who are impregnating, pultruding, or filament winding can program the system according to the type of resin and catalyst being used.

The Quadrax system can take three actions: First, if the change in temperature exceeds the preset parameters for that reaction, the system activates a mixture dilution sequence to slow or stop the reaction. The dilution sequence can also be manually activated. Secondly, a viscosity sensor reacts to build-ups in viscosity, which may indicate an out-of-control exotherm reaction. If the rate of viscosity build-up is too great, the system will act to halt the reaction by dilution. Thirdly, a temperature sensor acts as an independent backup to activate the dilution feature if the reaction exceeds the preset minimum safe temperature. Cost of the system is $24,500. (CIRCLE 27)

The Composite Specimen Cutter, a machine that produces specimens for compressive and tensile testing in large quantities, was introduced by Venus-gusmer Corp., Kent, Wash. Through the use of removable fixtures for tab bonding and vacuum bagging, coupons can be prepared off-site for rapid mounting and cutting on the machine. Standard tooling cuts specimens of 0.5 x 9 in., while optional tooling can cut provide sizes up to 1 in. The machine costs $42,000. (CIRCLE 28)

Associated Pacific Machine Corp., Los Angeles, introduced the model 620 M16 roller press for die cutting composite materials up to 63 in. wide. The machine's reportedly unique double-sided configuration allows an operator on one side to feed a cutting pad to the roller press, while an operator on the other side prepares the next cutting pad. Then, they are able to switch tasks while remaining at their respective worktables. Cutting cycle time is reportedly around 30 sec. (CIRCLE 29)


Hercules Advanced Materials & Systems Co., Magna, Utah, and Rhone-Poulenc of France (with North American headquarters in Princeton, N.J.) are now jointly developing, marketing, and selling ceramic fibers. As a start, Hercules will market and sell Rhone-Poulenc's silicon-carbonitride fiber, called Fiberamic, in North America.

Fiberamic is a multifilament, continuous ceramic fiber for high-temperature polymeric, ceramic, and metal composite applications such as hypersonic aircraft structures and engines. It reportedly remains amorphous up to 2550 F and is available as 250- or 500-filament continuous tow or as fibers as short as 0.03-in. Fiberamic is currently manufactured in France at a Rhone-Poulenc pilot facility, and the agreement allows for U.S. production if market demand requires a domestic source. (CIRCLE 30)

Tonen Corp. of Japan (represented in the U.S. by Tonen Energy International Corp., N.Y.C.), introduced its new, ultra-high-modulus, pitched-based carbon fiber, said to offer superior handling characteristics. Called Forca FT700 and FT500, the new fibers have 100 and 70 Msi moduli, respectively, together with 470 and 430 ksi tensile strengths. Both are available in 3000-filament tows. The company also produces silcon nitride fibers. (CIRCLE 31)


Premix, Inc., North Kingsville, Ohio, introduced two new polyester sheet molding compounds, Premi-Glas 2201-22 AIG and 2201-30 AIG, that reportedly meet the new FAA rate-of-heat-release criteria. They are processed in the same manner as other SMC, at modling temperatures of 300-320 F. Relative to Premix's earlier 2200-AIG version (see PT, May '88, p. 15), the new grades are higher in tensile and flexural strength and modulus, higher in Izod impact, lower in density, and lower in smoke generation. Of the two new grades, 2201-30 AIG has the higher mechanical properties and density. (CIRCLE 32)

ICI Advanced Materials' Fiberite Molding Materials Group in Winona, Minn., introduced a toughened modling compound alloy based on an epoxy matrix. Thermoplastic materials are reacted into the epoxy backbone, enabling the compount to retain its thermal properties, dimensional, stability, and creep resistance, while gaining some of the toughness of a thermoplastic. This is the latest development in a program that ICI has reported on at each of the last two SAMPE meetings (see PT, Aug. '88, p. 34; July '89, p. 27). The new compound, named TEM 9001, can be compression, injection, or transfer molded. (CIRCLE 33)

Ciba-Geigy Corp.'s Furane Aerospace Products, Los Angeles, Calif., exhibited a novel vacuum-bag molding process for reinforcing honeycomb with Epocast "syntactic" epoxy patties (i.e., filled with hollow microspheres). First, a frozen epoxy patty is thawed, and the honeycomb material is marked off and prepared for reinforcing on a vacuum table. The patty is then placed on the top of the honeycomb, and the part is sealed with a vacuum bag. Then, a vacuum is applied to draw the epoxy into the honeycomb, and the trimmed part is cured in an autoclave or oven. The patties can be co-cured with other composite materials, such as prepregs and film adhesives. (CIRCLE 34)

Quadrax Corp., Portsmouth, R.I., is developing a line of interlaced thermoset tape prepreg fabrics to complement its thermoplastic products of this type. The first new thermoset product is made from ICI Fiberite's AS4/3501-6 carbon fiber/epoxy tape, and Quadrax plans to offer other thermoset materials as demand dictates. Tapes are formatted into a broadcloth material in rolls up to 10 ft wide or supplied as debulked preforms ready for vacuum bagging. Manufacturing improvements realized during the development of the thermoset tape fabrics enabled a recent lowering of the price of the thermoplastic counterparts by 20%. (CIRCLE 35)

Thermoplastic prepregs with low dielectric constants are new from Heltra Inc., Quakertown, Pa., sub. of Courtaulds Advanced Materials. Heltra uses a proprietary stretch-breaking process to make staple-spun yarns from high-performance fibers. Conformability reportedly allows ply sections as thin as 2 mil. Material configurations include fiberglass/polyetherimide, quartz/PEEK, and specialty products using ceramic fibers and liquid-crystal polymers. The novel materials are being tested by Advanced Composite Products, North Brandford, Conn., in applications such as radomes. (CIRCLE 36)


Hi-Tek Polymers, Inc., Jeffersontown, Ky., which was recently puchased by Rhone-Poulenc, announced two new cyanate ester materials for RTM of parts requiring dielectric performance. AroCy M-20 is a low-meltviscosity (375 cp at 180 F) prepolymer that is said to provide hot/wet service to 350 F. Additionally, the company is working on a developmental monomer, RTX 366, which is said to provide low moisture absorption (0.6% at 212 F saturation) when polymerized and cured. RTX 366 is a supercooled liquid at room temperature. The material should be commerically available by the end of the year. (CIRCLE 37)


Extruded film of Vectra LCP is new from a recently opened facility at Hoechst Celanese Corp.'s Advanced Technology Group In Greer, S.C. The LCP film is produced using a cast film extrusion process and is priced at around two-thirds the cost of similar gauge polyimide film. Thicknesses possible at the new facility range from 0.5 to 187 mil. Vectra LCP film is expected to be used in printed circuit boards, aircraft interiors, and chemically hostile environments.

Hoechst Celanese also introduced Durel polyarylate film, which costs 10-20% more than polycarbonate film of similar gauge. In the future, the company plans to develop films of its Fortron PPS and Riteflex TP polyester elastomer and will consider the question of whether to license the film-making technology when demand develops. (CIRCLE 38)

3M Co., St. Paul, Minn., introduced a new structural adhesive epoxy film for surfacing. Scotch-Weld AF 3113-5 is said to minimize the incidence of honeycomb mark-off and surface imperfections that telegraph through the laminate layers during cure, creating fewer voids or pinholes that require further sanding and filling in the paint shop. The film can be cured at temperatures as low as 225 F or co-cured with 350 F cured materials. (CIRCLE 39)

Another new epoxy film from 3M, Scotch-Weld AF 32, is said to provide the impact resistance needed for aircraft parts subjected to blasts of sand, runway debris, and bead-blasting paint removers that are replacing solvent paint strippers. A high concentration of nitrile rubber results in the greater toughness and resistance to impact, and it is said to withstand grit blasting 4-10 times longer than standard epoxy surfacing films. The material's upper service temperature is 350 F. (CIRCLE 40)
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Title Annotation:Society for the Advancement of Material and Process Engineering
Author:Evans, Bill
Publication:Plastics Technology
Date:Jun 1, 1990
Previous Article:New stretch-blow molding resin: polymethylpentene.
Next Article:PET compound molds faster, is less moisture-sensitive.

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