Plastic materials for military applications must be able to withstand demanding conditions. Whether at land, air, or sea (and even space), part failure is not an option. For technical designers and buyers alike, supporting the mission means choosing the right materials.
Do you need military approved plastics that can withstand the high temperatures of desert battlefields? What about polymers that provide not just water resistance, but resistance to saltwater at low temperatures? How about specialty plastics that can withstand the g-forces encountered during air support sorties?
Understanding application requirements is important, but compound selection can also mean picking polymers that are approved specifically for military use. So how can you determine what you need? And how can choosing the right partner strengthen your supply chain?
The Acrylic Glass Example
Poly(methyl methacrylate) or PMMA is an acrylic glass that’s better known by brand names such as Plexiglas®. Strong and lightweight, this versatile plastic is typically opaque or clear. PMMA weighs only about half as much as regular glass, but has considerably greater impact strength.
Unlike other plastic materials, Plexiglas can be manufactured to impart light-transmitting, light-focusing, or light-diffusing properties. In addition to offering resistance to ultraviolet (UV) rays, this synthetic polymer can reflect noise, provide heat shielding or heat insulation, and resist scratching.
Production and repair personnel like working with Plexiglas because it’s tough enough to withstand handling and installation, and can be sawed, routed, and polished to meet application requirements. This PMMA is also desirable because it burns with little smoke and doesn’t form acutely toxic gases.
Military Specifications and Material Testing
Do the material properties of PMMAs make them right for every military application? It’s not that simple. For buyers who work with organizations such as the U.S. Department of Defense (DoD), there are published military specifications to consider. (Typically, however, Plexiglas parts are used in aircraft cabin windows, instrument panels, canopies, wingtip camera lenses, and outer laminates.)
Although these specialty acrylic materials are available in a range of sizes and thicknesses, buyers need to choose plastic products that meet military specifications such as MIL-PRF-5425E. What do military standards like this mean, and why are they so important?
In the case of MIL-PRF-5425E, this military standard covers material properties such as optical quality, transparency, and heat resistance. In turn, MIL-PRF-5425E incorporates 10 different test methods from the American Society and Testing and Materials (ASTM).
Typically, supplier websites and data sheets indicate whether a particular plastic meets various ASTM standards. By working with a supply chain partner who can help you with material selection, however, you can simplify the task of sourcing military-approved plastics.
U.S. DOD standards aren’t the only military specifications in the world, of course. For example, the North Atlantic Treaty Organization (NATO) publishes standardization agreements (STANAG) that establish common requirements for equipment and materials among member nations.
Underwriters Laboratories (UL) also publishes standards for security applications. UL 752 defines nine protection levels, each for a specific type of ammunition. For example, a Level 1 UL rating is for a 9-mm full metal copper jacket with a lead core. UL’s supplementary shotgun level is for 12-gauge shotguns.
To select the right military-approved plastics then, you’ll need to understand application requirements, know which standards apply, and also consider program budgets. With regard to costs, consider the case of mine-resistant ambush protected (MRAP) vehicles that U.S. forces use in Afghanistan.
These military vehicles feature windshields made of an expensive ballistic glass, but it was a specialty laminate that captured headlines several years ago. According to an estimate from the Defense Logistics Agency (DLA), using a tear-away film could help limit windshield replacements and save the Pentagon as much as $75 million annually.
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