SEEMAN COMPOSITE RESIN INFUSION MOLDING PROCESS (SCRIMP) TECHNOLOGIES
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| Overview: | The SCRIMP
(Seeman Composites Resin Infusion Molding Process) is a new vacuum-assisted
resin transfer molding process producing parts excellent for marine, aerospace,
transportation, and infrastructure applications. The process is a proven
method of producing high quality composite parts made from a wide range
of fiber and resin combinations. All commercial fibers, core materials,
and any resin in the range of 50 centipoise to 1000 centipoise will “SCRIMP”
with outstanding results. The process can be run at room or elevated temperatures.
SCRIMP can produce large (2,000 sq. ft.) parts, using both single skin and
cored construction, and highly complex three dimensional trussed parts weighing
up to 3,000 lbs. The resulting composite material properties directly compare
to properties that had only been achievable in highly controlled expensive
autoclave processes.
The SCRIMP process is inherently repeatable. Once equilibrium resin content is achieved (55% to 60% fiber volume, depending on fabric architecture) the process stops. Aerospace grade quality is ensured by first eliminating all air voids before the resin is infused, enabling the fabric pre-form to act as an effective breather layer. As the resin is infused, it travels in controlled waves that work to completely wet out the reinforcing fibers and eliminate any voids that could be created by the VOCs emitted by the resin during the cure cycle. The process has been used to infuse laminates up to 6 inches thick with the same high quality results as a simple 1/8 inch laminate. The Navy has extensively tested SCRIMP laminates and has concluded that the void content can not be detected with standard ASTM methods. With or without a gel coat, composites produced using SCRIMP exhibit pinhole free surfaces. The Navy has developed prototypes of varying structures, such as ship’s masts, Navy Seal submarines, and sensor systems. The SCRIMP process also is being used to make sailboats, railcar bodies, intermodal shipping containers, bridge decks, windmill blades, and pilings, among other applications. One example of the application of the SCRIMP process is the Hardshaft manufacturing process. The process is used to manufacture marine construction products, such as fiberglass tubular pilings and marine fender panels. The process has extreme versatility and can produce pilings of any size up to 300 feet long and six feet in diameter. Benefits specific to the Hardshaft application are:
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| Compliance Benefit: | The SCRIMP
closed system may decrease the need for an air permit under 40 CFR 70
and 40 CFR 71. In addition, less hazardous materials (i.e., solvent)
are required for the SCRIMP system therefore, the possibility that the facility
would meet any of the reporting thresholds of SARA Title III (40 CFR
300, 355, 370, and 372; and EO 12856) is decreased.
The compliance benefits listed here are only meant to be used as a general guideline and are not meant to be strictly interpreted. Actual compliance benefits will vary depending on the factors involved, e.g. the amount of workload involved.
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| Materials Compatibility: | No materials
compatibility issues were identified.
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| Safety and Health: | The SCRIMP
process increases worker safety by reducing VOC emissions. Consult your
local industrial health specialist, your local health and safety personnel,
and the appropriate MSDS prior to implementing this technology.
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| Benefits: |
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| Disadvantages: |
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| Economic Analysis: | The SCRIMP
process is a patented system licensed for $25,000. Hand layup, the conventional
method of marine construction, is a labor-intensive process resulting in
a product with relatively high porosity and low fiber content that reduces
strength and stiffness. The unit cost per pound of labor and materials for
a generalized structural configuration, based on an assumption of $40/hour
shipyard labor, is less than $10/lb. The SCRIMP process may decline in price
in the future, as it is currently being used for producing prototypes in
many applications. The SCRIMP process, currently at a comparable cost, produces
a higher quality product while emitting fewer VOCs, which can endanger workers.
Currently, the cost of using the SCRIMP process is less than $10/lb.
Based on the construction of four, one-half scale midship sections of a medium-sized 280-ft., 1200-ton naval combatant, the SCRIMP process produced a hull section weighing slightly under 23,000 pounds, including 13,000 pounds of glass and 7,000 pounds of resin. The production time for fabricating the hull section was 3,154 labor hours. Another example of an application that has been used more widely is pilings. The following assumptions were used to compare the cost of Hardcore pilings using the SCRIMP process to conventional CCA pilings: Assumptions:
Although the Hardcore pilings cost more initially than conventional pilings, the costs involved in replacing the shorter-lifespan, conventional pilings increase the overall costs of conventional pilings significantly. In the longterm, Hardcore pilings are more cost effective. Click Here to view an Active Spreadsheet for this Economic Analysis and Enter Your Own Values.
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| Approving Authority: | Approval is controlled locally and
should be implemented only after engineering approval has been granted.
Major claimant approval is not required.
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| NSN/MSDS: |
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| Points of Contact: | Navy: Dr. Milton O. Critchfield Naval Surface Warfare Center, Carderock Division 655 West Bethesda, MD 20817-5700 Phone: (301) 227-1769 FAX: (301) 227-1020
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| Vendors: | This is not meant to be
a complete list, as there are other manufacturers of this type of
equipment. TPI Composites, Inc. P.O. Box 328 Warren, RI 02885 Phone: (401) 245-1200 FAX: (401) 247-2669
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| Sources: | Research Release "Low Cost, High
Quality composite Ship Structures Technology Demonstrated," Headquarters,
David Taylor Model Basin, Naval Surface Warfare Center, Carderock Division,
Bethesda, MD, May 1993 Nguyen, Loc D., Thomas Juska, and J. Steven Mayes, "Evaluation of Low Cost Manufacturing Technologies for Large Scale Composite Ship Structures," Naval Surface Warfare Center, Carderock Division, West Bethesda, MD, Presented to 38th Structures, Structural Dynamics, and Materials Conference and Exhibit, AIAA/ASME/AHS Adaptive Structures Forum, Kissimmee, FL, April 7-10, 1997
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