Lots new in composites processing equipment.

For SMC, RTM, Pultrusion and More...

From new SMC presses and automation auxiliaries to RTM computer monitoring software, preforming and tooling novelties to "hybrid" pultrusion concepts combining filament winding or thermoplastic pultrusion, there are a host of new equipment developments to report from the recent SPI Composites Institute annual show and conference in Cincinnati. Also included below are new spray-up hardware and software, a Japanese process for marble bathtubs, and a novel one-shot process for molding foam-core boats, auto parts, and sanitary ware with decorative thermoplastic skins.

SMC/GMT PRESSES & AUTOMATION

A new line of SMC compression presses is available from St. Lawrence Press in sizes from 100 to 2500 tons. These "Straight Side" presses have housing-type construction with tierods and eight-point, square-type gibing. They're long-stroke presses with closing speeds up to 2000 in./min and options such as leveling, ejectors, programmable controls, and quick die change.

Two German builders of sophisticated compression presses for SMC and glassmat/thermoplastic (GMT) sheet have recently signed new representation agreements for plastics markets in North America. Wemhoner Pressen is now being represented by Marvel Equipment (which also reps St. Lawrence Press in some states); and Dieffenbacher is represented by Girard Associates, which formerly handled Hoesch MFD. The latter was acquired by Dieffenbacher last spring.

American Composite & Automation Co. (which also goes by the name CTA of America) is a new firm offering automation systems for SMC, GMT and other processes. It's a joint venture of Composite Technologie Automation (CTA) GmbH, a German composites fabricator and automation equipment developer, with IMTA Manufacturing Technology & Automation Co., Inc., a supplier of automation for the aircraft industry. CTA of America (represented by Marvel Equipment) will supply press loaders and unloaders, transfer robots, magazine feeders for blanks of SMC or GMT sheet, and complete systems integration.

Sophisticated SMC robotics are now available at lower cost, thanks to a representation agreement between ISI Robotics of Fraser, Mich., and RP/C Machinery Corp., a systems integrator. ISI, said to be one of the largest automation firms in the world, brings its experience in metal stamping to plastics, offering standard components that bring the price down to around half of previous levels for automated press loaders/unloaders and bonding-cell robots. These can start at around $50,000 for air-operated models, and range up to $110,000 for programmable AC or DC servo-driven units. DC servo-driven robots can move at extremely high speeds--up to 5 ft in 1 sec with |+ or -~0.015-in. accuracy, according to RP/C president Gene Wood.

RP/C also represents Powermatic, which has an improved version of its Series V router for large SMC parts (see PT, March '90, p. 25). It now has an optional automatic tool changer and higher spindle speed--30,000 rpm vs. 21,600 rpm previously--which is said to give better edge finish with no fiber pullout. Tests last year of deflashing a General Motors A-Van hood demonstrated what could be accomplished with such high-speed spindles, vibration-free frame construction, and precise CNC control. Using a bevelled cutter, the Powermatic Series V reportedly deflashed the hood--just "kissing" the part at speeds up to 800 in./min--producing a rounded edge without damaging either the in-mold coating or the SMC substrate. The router deflashed the hood's 260 in. of circumference in under 40 sec.

In other SMC auxiliaries, Buckeye Machine & Fabricators came out late last year with a "more affordable," semiautomatic, two-axis SMC slitter. For around one-third to half the price of the company's fully PLC-controlled two-axis slitter, Buckeye offers a model with PLC control of the cross-cut, plus manual setting of the in-line slitters. Prices start at $39,000.

NEW SMC TEST INSTRUMENTS

Last year, Diffracto Ltd. introduced the D-Sight Test Plaque Station, a smaller version of its video surface inspection system, designed for SMC test plaques rather than full-size auto body panels. Now, Diffracto has come out with the TPS-2 model, featuring software enhancements to identify short-term as well as long-term waviness and to accommodate large variations in gloss and color within the surface of a single plaque. Also being offered for the first time is a series of five master reference plaques for repeatable calibration. The TPS costs around $55,000, less than half as much as a full-scale D-Sight AS-2 Audit Station.

A new, low-cost dielectrometer designed specifically for QA/QC testing was introduced by Micromet Instruments. The ICAM-1200/QC Testing Station contains new software for simple, automated dielectric cure testing of thermosets for both incoming and outgoing QC purposes. The system can be used for testing SMC/BMC, RIM, RTM, epoxies, and foams. Monitoring the curve of "ion viscosity" (mobility of ions in an oscillating electric field) versus time during cure, the unit looks for user-specified "critical points" such as the flow point, viscosity minimum, gel inflection point (point of most rapid viscosity increase), and cure endpoint. The system then performs automatic statistical quality control (SQC) testing for batch-to-batch variability, providing drift/trend alarms, automatic pass/fail determination, and detailed quality documentation.

Reusable, in-mold sensors permit dielectric testing to be incorporated in existing test molds used for spiral flow, resin content, shrinkage, and so forth. Alternatively, Micromet offers a new portable, air-operated press for testing and sample preparation. The MP-1200/QC MiniPress can supply up to 2000 lb of force over its 4 x 8 in. platen and is programmable up to 390 F by means of a personal computer or the unit's front-panel control. Test instrument with sensors but not PC monitor costs around $25,000. A MiniPress adds about $10,000.

EQUIPMENT FOR THERMOSET RECYCLING

Given the growing interest in thermoset composite recycling--especially among SMC molders--RP/C Machinery is establishing representation agreements with makers of size-reduction equipment. One of these is Jacobson Inc., which makes heavy-duty shredders, crushers, hammermills, and pulverizers suitable for composites. The equipment can reduce SMC to 20-22 microns, the size of calcium carbonate filler, but reground SMC has 7% lower density than calcium carbonate.

And the recycling interest isn't just for SMC. Chrysler Corp. in Detroit is considering use of regrind in RTM inner body panels for the new Viper sports car. Initially, Chrysler is experimenting with reground SMC as a filler in RTM.

RTM ADVANCES ON ALL FRONTS

Just a year ago, we reported that more sophisticated pumping systems and electronic control and monitoring functions were coming to RTM in order to satisfy demanding aerospace and automotive customers (see PT, May '91, p. 19). At this year's SPI meeting, Venus-Gusmer introduced a personal-computer RTM process and production monitor, developed specifically for automotive. The system can calculate ratio and feed rate of each component by means of mass-flow meters. It also monitors pressure at the mold inlet and temperature sensors on tanks and hoses, and will actuate alarms if any variable runs out of tolerance. It continuously displays the percentage of mold fill and shuts off the gun at 100% fill. Also shown on the screen are total amount of resin dispensed vs. the preset shot size. The computer detects when peak exotherm has occurred and can turn on a light at the mold to signal that it is ready to be opened. The computer also stores complete setup data for up to four molds and 39 material recipes (storage capacity is expandable).

Venus-Gusmer can supply the software and data-acquisition hardware alone or together with a PC or laptop computer. The system also comes with a separate data interface box for the pumping equipment, which has its own four-line LCD display. Since this is a custom-designed package specific to the RTM dispensing hardware used by the customer, typical cost is over $30,000.

Automotive and other large-area RTM parts, such as those on Chrysler's Viper sports car, are creating opportunities for large presses. Spokesmen for John T. Hepburn, Ltd. say they are now quoting presses almost as big as the biggest SMC presses--but with far lower pressure capability--for new projects such as an entire automotive underbody.

Meanwhile, for aerospace RTM, Venus-Gusmer also has a new PC-based system that monitors all critical temperatures, pressures, flow rates, and relative viscosity. All variables can be charted for trend analysis.

To meet the demand for uniform, pulsation-free mold filling, RTM pump manufacturers like Venus-Gusmer and Liquid Control have been moving upscale in equipment sophistication. At the same time, one RIM machinery supplier says its existing urethane equipment is just what the RTM market wants. Gusmer (a sister company of Venus-Gusmer) is recommending its variable-ratio DeltaRim models, ranging from 40 to 240 lb/min capacity. These have a double-acting Continuous Delivery Cylinder (CDC) pump system to provide uniform flow and unlimited shot sizes.

In less expensive RTM dispensing systems, Glas-Craft recently came out with its LPI (Low-Pressure Injection) system with a 4:1 pump, standard slave-pump catalyst proportioner, and capacity of 2 1/2 gal/min. A new gun design has a simple one-button on/off control, cleanout ports on both catalyst and resin sides, and a pump-stroke counter and reset switch. A first for Glas-Craft on this system is low-pressure recirculation of both catalyst and resin, designed to keep fillers in suspension. There's also both solvent and air flushing, and a transparent window to permit observing material in the static-mixing nozzle. A cart-mounted system with a short boom costs $8950.

And for only $3000, GS Manufacturing offers a new RTM system based on its Little Willie gun with a static-mixing extension, plus 5:1 air-motor pump and catalyst slave system. The system mounts on a 5-gal pail or on a wall for use with drums or Liqui-Bins. The system can also be used with saturator or resin-roller attachments.

WHAT'S NEW IN PREFORMING

Automated preforming continues to be an active area of R&D for RTM and SRIM. At the SPI meeting, Dow Plastics reported on experiments at its Freeport, Texas, composites lab aimed at defining a 60-sec preforming process. Dow considers its results encouraging, although it got down only to 70-80 sec. The company used a glass-mat dispenser from Finn and Fram that slits, crosscuts, and delivers the mat blanks to an infrared oven. Heated mat was simultaneously formed and trimmed in matched dies that incorporated steel-rule diecutting. Achieving rapid cooling was a major obstacle. Conduction from water-cooled forming dies was not adequate for thick preforms. A more promising alternative was drilling holes in the dies to allow compressed air to be forced through the part while in the die.

Cannon USA also reported at the SPI meeting on further developments of its Compotec automated preformer (see also PT, Jan. '92, p. 41). To help with its goal of reaching a 1-min cycle, Cannon uses low-inertia heating elements that heat to forming temperature in 3 sec and then cool to room temperature in another 3 sec. Cannon also revealed that it is working on a 3-D hold/slip frame contoured to the perimeter of the part, which is expected to reduce wrinkling, stretching and tearing of the mat when forming complex shapes.

Cannon also addressed the difficulties of preforming one layer of mat, which cools before it can be transported into the forming press. Consequently, Cannon and Owens-Corning Fiberglass Corp. of Toledo, Ohio, together developed a method of forced-air heating and cooling inside a box-like enclosure right at the preforming station.

C.A. Lawton Co., which has discussed its Compform "directed-energy" automated preforming system at the last two SPI Composites meetings (see PT, Jan. '90, p. 15), has formed a joint venture to develop and market the system with American GFM, a manufacturer of automated prepreg cutting equipment. The venture, also called Compform, is located at American GFM's facility in Chesapeake, Va. A GFM high-speed, ultrasonic mat cutter is used to maximize utilization of costly mat material. A demonstration line is already being shown to automotive and aerospace manufacturers.

RTM TOOLING DEVELOPMENTS

RP/C Machinery Corp. is working with press builder Hepburn and RF heating specialist Nemeth Engineering Associates, Inc. of Crestwood, Ky., on a novel method of RF curing for RTM. RP/C's Gene Wood anticipates that RF heating may chop mold cycles from 7 min down to 1 1/2 min. The approach involves mixing a reportedly inexpensive RF-susceptor additive into the resin, as well as coating one half of a metal mold set. Chrysler is considering investigating this approach for its Viper project.

Meanwhile, Chrysler spokesmen are very encouraged by their first results in a planned transition from epoxy to nickel-shell tooling for the Viper's RTM body panels. Electroformed nickel-shell tooling reportedly has advantages of being harder and more durable than epoxy or cast-aluminum tools, and it can withstand extended use at higher temperatures--up to 200-240 F. Running hotter improves the effectiveness of most low-profile agents and Chrysler hopes to achieve automotive Class A surfaces in the future without gel coating. Running hotter also could lead to shorter cycles.

The catch is that there are said to be few companies able to provide high-quality matched nickel-shell molds. One of those few is Ex-Press Process Equipment, an English custom molder and moldmaker, which is represented here by Fib-Chem Industries. The company reportedly has special expertise not only in electroforming matched tools, but also in framing the molds, installing guide posts, and backfilling the nickel shell with material having a compatible thermal-expansion coefficient. Nickel-shell molds are cost-effective for runs of 3000-5000 parts/yr, and some have lasted for over 44,000 cycles at elevated temperature, says Fib-Chem's Martin Baginsky.

Another innovative approach to RTM tool construction is being developed by ISORCA Inc., an R&D firm, with funding from the International Copper Research Association Inc. in N.Y.C. ISORCA is working with a major truck manufacturer, a custom molder, and moldmaker Portage Casting and Mold on a production test of an RTM tool cast from C95400 aluminum bronze alloy. The part, a cab structural support member, is now being produced in cast-aluminum RTM molds. The C95400 alloy is said to be much tougher and harder, providing longer life for long production runs and ability to run at higher temperatures, which may eventually lead to shorter cycles.

ONE-SHOT SANDWICH STRUCTURES

A new low-cost process available for licensing produces structures with one thermoplastic skin, a foam core, and an opposite skin of reinforced composite. The ACP process was developed and patented by Advance USA Inc. and first commercialized 18 months ago. As explained by president Michael O'Neill, the process involves pumping urethane foam chemicals into a closed mold that has a previously thermoformed sheet in one half and glass mat or cloth stuck to the other half with pressure-sensitive adhesive. The urethane material foams in the open space between the molds, bonds to the thermoplastic sheet, and also penetrates the glass mat, producing a solid reinforced laminate. The result is an integrally bonded sandwich structure with one tough, cosmetic surface.

Advance USA has used the ACP process to mold about 700 15-ft sailboats for JY Sailboats of Noank, Conn., as well as 132-gal water heaters for Vaughn Manufacturing of Salisbury, Mass. Vaughn has taken an ACP license to eventually begin its own molding. Another licensee is Viking Industries in El Dorado, Ark., which is developing a number of tub and shower products. Advance USA is talking to around 15 other potential licensees about possible applications in recreational vehicles, boats, appliances, and automotive--the latter including removable hardtops, interior door panels, trunk liners, structural bulkheads, truck roofs, wind deflectors, and sleeper boxes.

O'Neill says the process is inexpensive to get into, using FRP tooling and low-pressure urethane foam dispensing equipment. He says it's economical for production runs of 500 to 10,000 parts or so. A mold can typically produce up to 30 parts/shift.

PULTRUSION/EXTRUSION HYBRIDS

Among several pultrusion novelties discussed at the SPI meeting were two companies working on combining thermoset pultrusion with thermoplastic extrusion. One is extrusion overcapping of pultruded profiles, patented by Dexter Pultrusions Div., Aurora, Ohio, in 1990 (see also PT, Jan. '92, p. 41). The product has since been commercialized in production of over 1 million ft of product. Potential applications include doors, windows, and shelving for food-service and medical use. This hybrid process joins the creep resistance of thermosets with the smoother surface finish and greater weather, stain and scratch resistance of thermoplastics. Another major advantage of thermoplastics is design freedom--i.e., ability to easily form complex shapes and surface details that would be impossible or impractical with pultrusion. Also, thermoplastics lend themselves to downstream operations such as milling and laser printing, which are unsuitable for thermosets.

Dexter used a vertically mounted, crosshead extruder capable of 24 lb/hr to apply coatings from 4 to 30 mils or more of ABS, ASA and other styrenics. Typical profile tolerances of |+ or -~6 mils were achieved.

Dexter's manager of technology, Thomas J. Griffiths, cited three major technical hurdles to the process:

* The pultrusion process had to be optimized to minimize stops, which are incompatible with extrusion.

* The puller required greater clamping force than normal for extrusion pullers and tighter speed regulation than most pultrusion pullers. Dexter solved this by adding hydraulic clamps to an extrusion puller.

* Adhesion was the biggest problem. This required minimizing out-gassing from the thermoset by raising the initial die temperature. After experimenting with spraying a solvent-based acrylic adhesive onto the thermoset substrate, Dexter found it could eliminate the adhesive through a combination of a proprietary surface treatment of the substrate and addition of a thermoplastic additive to the unsaturated polyester formulation.

A second example of such a hybrid process involves encapsulation of a pultruded S-glass/epoxy structural member and a cable assembly inside a thermoplastic elastomer shape (see diagram). The product is an underwater "towed-array" sonar cable produced for the U.S. military by American Composite Technology of Boston. It's manufactured in 1000-ft lengths from pultrusions and fiber optics produced in separate operations.

Meanwhile, a different approach to pultrusion overcapping is being developed by Sherwin-Williams Co. The firm has been working with customers (one of which is applying for a patent) on in-line coating of exterior durable profiles with the firm's one-component polyester in-mold topcoats that were originally developed for SMC.

Another sort of hybrid process is being explored by equipment maker Pultrusion Technology to make a composite I-beam by combining pultrusion and filament winding. According to PTI's Jeff Martin, the concept is to circumferentially wind glass rovings onto a cantilevered metal mandrel that extends into the pultrusion die. The mandrel starts out round and makes a transition to square. Inside the die, the vertical sides of the square are collapsed to form an I-beam. Martin says the round-to-square transition has been demonstrated in filament winding/pultrusion of 100-mm square tubes; the next step will be to try an I-beam shape. Martin says the wet-wound rovings easily slide along the mandrel, using Nexus polyester-fiber surfacing veil as a "slip sheet." (Nexus is a product of Precision Formed Fabrics.)

Martin says this hybrid process should have several advantages over straight pultrusion with continuous-strand mat as a method of producing structural I-beams. The main ones are the ability of filament winding to put the fibers in precisely the desired orientation for optimum strength and the ability to use lower cost rovings instead of mat. Glass mat's poor wet strength is also no longer a problem in processing. (PTI, by the way, offers roving winders as accessories for its pultrusion machinery.)

What is probably the tiniest pultruded section ever made--down to 10 mils in diameter--is being produced by DFI Pultruded Composites Inc. in Erlanger, Ky. These pultruded "Micro Rods" of 60% carbon fiber in epoxy can be made from a single end of 1K carbon roving. DFI says 50 mils was previously the smallest pultrusion. Special impregnation, tooling and curing techniques are used to encapsulate fragile high-modulus carbon fibers. Potential uses include twisted structural cables, woven preforms for carbon-carbon composites, and ultra-high-modulus rod structures for military uses.

NEW FOR SPRAY-UP

To help open-mold FRP fabricators get a better handle on their costs, Venus-Gusmer has come up with an FRP cost estimator software package on a floppy disk. It calculates the weight and material cost of a part, laminate thickness, glass/resin ratio, and resin-batch volume or weight. It also calculates how much resin is left in a barrel according to a dipstick reading. "All the most common math routines used in an FRP shop are included," says marketing manager John Raymer, "including a gelcoat cost factor to give you the total material cost of the part." FRP Estimator costs less than $400.

New in spray-up guns is the Little Willie Internal-Mix Gelcoat Gun from GS Manufacturing. The design, incorporating a static mixer, is said to be simple and easy to maintain. It costs $2995.

An innovative resin-roller cleaner from Venus-Gusmer is said to provide more efficient cleaning, especially with the new non-solvent resin emulsifiers. The simple device consists of several parallel wires stretched over an inclined frame, which reach down into even the deepest roller grooves to release stubborn resin, the company says. What's more, it fits inside a 5-gal pail, so there's no need to get material or cleaner on your hands. Price is under $200.

MOLDED MARBLE BATHTUBS

A new Japanese process for molding synthetic-marble bathtubs is available for licensing from Hoxan America. At last year's SPI conference, Hoxan described its process (also available for licensing) for SMC molding of unitized bathrooms. This year, Hoxan presented its "MTM" (Middle Temperature Molding) process for cultured-marble bathtubs. Molding productivity and finished-part performance are said to be superior to either typical marble molding or BMC processes. Both molding speed and boiling-water resistance are reportedly enhanced by two-step curing at 140 F and then 195 F. This eliminates the need for an accelerator, which improves molded color.

The process uses electroformed nickel-shell molds, which are then chrome plated. The tubs have three layers: a gelcoat inner skin, applied by a robot to the core-side mold half while it rotates on a turntable; a middle layer cast of terephthalic polyester and silane-treated glass powder; and an outer layer of previously cured glass/polyester laminate, which is attached to the cavity-side mold half. The latter eliminates the need for any secondary lay-up of supporting material.

Hoxan produces the casting mix in a jacketed bowl mixer. The detachable mixing bowl subsequently serves as a dispensing pump (with screw discharge) for the casting process. Cure time is only 15-20 min in the mold, plus 10-15 min post-cure.

Hoxan also has a licensable process for producing SMC sanitary ware, described at last year's SPI conference. In Japan, Hoxan molds complete unitized bathrooms, but the process could also be used for just bathtubs or tub/shower units. The complete technology package includes formulating, mixing and molding. Of particular interest are three techniques for achieving a variety of decorative finishes: 1) robotic spraying of gelcoat onto a mold half mounted on a turntable; 2) molding a colored or printed nonwoven fabric or glass veil into the surface of the part; or 3) bonding a previously molded cultured marble inner shell to the molded SMC outer support shell.