Types of Armor:
Hard armor is a term used to describe a body armor plate which has been fabricated in such a way as to form a rigid or hard plate. The result, regardless of materials used, directly correlates to a significant increase in the ballistic resistance of the materials used. This effect can be further improved through the use of enhanced materials. Hard armor is heavier and more cumbersome than soft armor, however it is required in situations where impact from rifle rounds is a possibility, whereas soft armor is incapable of defeating such projectiles.
Soft armor relates to those applications which are comprised of numerous layers of losely fit ballistic sheets which have not been formed into a hard plate. The use of soft armor is common in law enforcement and other professions where concealment and comfort are preferred, especially when worn through an entire shift on a daily basis. Although more flexible than hard armor, soft armor is limited in scope as a result of the lower levels of protection provided.
Materials Used In The Manufacturing Process:
Steel was the first commercially available material used to defeat the penetration of projectiles, starting as early as WWI. However, due to the fact that steel plates can create excessive spall, which can result in secondary fragmentation injuries. Some manufacturers still provide steel plate products, selling exclusively to civilians, however we DO NOT sell steel plates due to safety concerns as demonstrated in detail on our Videos page. Even with the use of “spall resistant” coatings, which are nothing more than liquid truck bed liner, spall and fragmentation should be a major concern to anyone currently utilizing and relying upon steel plates.
Aramid fiber is produced by spinning a solid fiber from a liquid chemical blend. This causes the polymer chains to orientate in the direction of the fiber, increasing strength. Perhaps the most widely known aramid, Kevlar, was developed by Stephanie Kwolek at DuPont in 1965. This high-strength material was first commercially used in the early 1970’s as a replacement for steel in racing tires and later evolved into a primary component of various ballistic applications. Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite material components. In modern ballistic applications Kevlar can be seen in both hard and soft armor. Although limited to stopping low velocity projectiles, Kevlar can also be used to enhance less resistant armor plates, or as spall protection in applications for buildings and vehicles.
Polyethylene fibers have replaced Kevlar in many modern hard armor applications, due to greatly improved ballistic resistance and a significant reduction in weight. This is a result of the dense molecular chains formed when processing UHMWPE fibers, and the fact that dense impregnated resins are no longer required. Polyethylene armor systems are manufactured by bonding unidirectional UHMWPE (Ultra High Molecular Weight Polyethylene) fibers over an HDPE (High Density Polyethylene) sheet. The sheets are then cut to a shape and placed in a mold where it is then compressed under high heat and pressure resulting in a cohesive, lightweight hard armor plate. When struck by a projectile the plate delaminates at the point of impact, distributing the force over a wide area while trapping the round within the plate itself, thereby eliminating spall entirely.
Polyethylene can be used independent of other materials to form Level III plates capable of defeating .223/7.62 rounds, however it cannot stop armor piercing ammunition without the addition of ceramic breaker plates.
Nonmetallic materials combined with fiber to form composites, ceramics are now widely used in combination with Polyethylene based materials in order to provide Level IV protection, capable of defeating armor piercing ammunition. The ceramic overlay is used on the exterior of the Polyethylene plate and acts as what is referred to as a “breaker plate”. The hardness of the ceramic layer causes the projectile to fragment on impact. The Polyethylene material then acts as what is referred to as a “backer plate”, trapping the fragments within the material to eliminate spall while fragmenting and defeating the projectile.
The NIJ, or National Institute of Justice, has set parameters by which body armor is classified according to its level of ballistic resistance. It is a direct result of the materials used and the process by which armor systems are fabricated. The chart below outlines the various levels of protection assigned by the NIJ for each particular caliber. Use the chart below to help determine which grade of armor is best suited for your purposes.