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Filling the Need for Consistent, Reliable and Cost-Effective Composite Core Material in Sandwich Panels

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Customer Information:

Founded in 1985, ACP Composites is a women and family-owned composite materials fabrication company that specializes in the design and manufacture of composite structures, plates, flat panels and other advanced composite products. The company supports a number of industries including aerospace, military and defense, medical, transportation, marine and more. Each of these industries have numerous unique requirements and specifications for each application, which is why the company follows a principle of ‘customer-centric innovation’. Instead of only offering a few convenient or conventional material options, ACP offers high quality, cost-effective composite materials to meet each customer’s specific application.

Material Challenge:

ACP found the need to provide a panel that appeals to their customers that don’t necessarily require the rigorous engineering and processing standards of aerospace, but still meets the company’s high-quality standards. More specifically, they wanted to offer a sandwich panel that is versatile, reliable, but is more cost-effective compared to other panels that utilize the commonly used core material, Nomex Honeycomb. It also needs to be available in a variety of densities and thicknesses. ACP decided the best way to achieve these requirements is with the use of a polyurethane foam core material.

Another necessity was that the foam needed to be stable enough to survive ACP’s 250° F processing temperatures and applications without deforming, shrinking or changing in any way.

“We’ve tried and tested every foam you can imagine, I’ve had foams catch on fire, some have even collapsed during processing,” said Justin Sparr, CEO of ACP Composites. “Other foams that could do the job, were over-priced or had too long of a lead. So, it would restrict us from carrying out our commitment to continuously meet our customers’ delivery and production schedules.”

Key Requirements:

  • Stable, high-performing foam core material
  • Cost-effective
  • Withstands ACP’s 250° F (121° C) processing temperatures without deforming
  • Can be cut into a variety of thicknesses
  • Available in a range of densities
  • Highly machinable
  • Readily available without a hefty minimum quantity requirement or long lead times

Solution and Application:

Ultimately, ACP Composites found that General Plastics’ LAST-A-FOAM ® FR-3700 series polyurethane foam was the most consistent and reliable material to utilize that met all of their requirements.

“General Plastics’ foam is perfect for our needs,” said Sparr. “It is a high-performing, economically viable solution that stays stable under our high-temperature processing applications. The company also offers comprehensive technical data sheets on all their foam materials, which makes it easier for customers to verify it fits their application requirements.”

FR-3700 is a rigid, closed-cell, flame-retardant polyurethane foam available in a wide range of densities. Tougher and less friable than other rigid foam materials, this aerospace-grade, BMS 8-133-qualified foam enables cutting of crisper edges, making it well-suited to machining complex shapes for composite cores. It exhibits a high strength-to-weight ratio due to its cellular structure and cross-linked resin. LAST-A-FOAM® FR-3700 has great resistance to water absorption, and will not swell, crack, or split on exposure to water. This series is non-abrasive and can be machined with standard high-speed steel (HSS) cutting tools.

Military Solar Array

Photo courtesy of ACP Composites.

General Plastics’ foam is used in a number of ACP’s customer applications. For instance, the foam is used as core material for portable, field-deployed military solar arrays. When using electronics in the field, soldiers need a lightweight solar array that produces bulk energy to charge batteries and other electronics anywhere they are. ACP found that General Plastics’ foam was perfect for this application as it fit the mechanical and budget needs for their customer.

Medical Positioning Table

Another way that the foam panels are used is for patient positioning tables in the medical industry. General Plastics’ foam core allows for ACP to install carbon fiber inserts within the panel, which gives the option to drill a hole through it or bolt into it. This type of carbon fiber table usually uses a polyacrylamide foam core, however that material is more expensive than polyurethane foam with a much longer lead time. When using General Plastics’ foam, the panel for the table was produced quickly, with the same dimensional stability and imaging clarity as polyacrylamide foam, but with a much lower price point. The customer was pleased with the foam’s low density and ease of machining and ACP now has a standing order for the product.

“Overall, I always know what to expect with General Plastics,” said Sparr. “They’re easy to work with and I know I’m always going to receive a quality product that the company stands behind.”

3700 Benefits

  • Stable and inert
  • Flame retardant
  • High strength-to-weight ratio from cross-linked resin
  • Resistant to most chemicals and solvents
  • Easily shaped with common woodworking tools
  • Performs well as wood replacement
  • Will not support fungal growth

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