Kevlar vs Steel vs PE (Polyethylene) Body Armor
Kevlar, steel and Polyethylene (PE) are the most used materials in the manufacture of body armor. Kevlar is mainly used to make soft body armor, while steel and Polyethylene are used to make hard body armor. Kevlar has revolutionized the development and manufacture of body armor. Body armor before the introduction of Kevlar was bulky and rather uncomfortable to wear. Kevlar is way lighter and is said to be up to five times harder and stronger than steel.
PE (Polyethylene) body armor comes in as some middle ground between Kevlar and steel body armor. While it not as lightweight as Kevlar, it is a lot lighter than steel. PE is a thermoplastic material. PE body armor is manufactured by bonding Unidirectional UHMWPE (Ultra High Molecular Weight Polyethylene) fibers over a high-density PE sheet. PE body armor plates work in a very unique way. When a bullet is fired, it spins as it moves forward. The spin causes friction when the bullet hits the PE armor plate. This friction causes the polyethylene material to melt, and then hold on to the bullet as it cools down and re-hardens.
Below, we explore each of these materials, and what the body armor they produce looks like. We’ll also seek to understand which is the most suitable body armor material while facing threats of different kinds.
Kevlar Body Armor
Today, you cannot avoid exploring the topic of Kevlar when you start getting into the nitty-gritty of body armor. Kevlar is a synthetic fiber that has incredibly high tensile strength. Kevlar’s molecules are unidirectional and parallel to each other. This makes them very tightly bound, hence the high tensile strength. Kevlar is ideal for making body armor because it is strong, lightweight, corrosion and rust free, and it absorbs vibrations quite effectively.
Kevlar can be classified into three grades according to its quality. The grades are standard Kevlar, Kevlar 29, and Kevlar 49. Standard Kevlar is very stiff and is used to make tires. Kevlar 49 is mainly used to make plastic consolidations for bicycles, boats, and airplanes. Kevlar 29 is the most ideal Kevlar for the manufacture of body armor. It is used to make brake linings, industrial cables, and asbestos replacements as well.
Kevlar is manufactured by a company known as DuPont. In scientific terms, the material used to make Kevlar is referred to as poly-para-phenelyne-terephthalamide. This polymer is heated and pushed through a sieve while hot. The resultant fibers are used to weave super-stiff and high-tensile sheets or mats that are now called Kevlar.
As mentioned earlier, Kevlar bulletproof vests are mainly classified as soft body armor. They provide protection against low to medium velocity firearm rounds. Many of them will not be able to handle fire from high-velocity rifles. In as such much as they may be able to stop bullets fired from some lower caliber rifles, the blunt trauma would be dangerously high. Blunt trauma could cause injuries to the ribs, heart, or lungs. There more layers of Kevlar that a bulletproof vest has, the more protective it is.
Despite being such a tough and strong material, Kevlar can be damaged by ultraviolet rays. It breaks down when exposed to sun rays that have UV radiation. Dry cleaning, bleaching agents, and frequent washing can also reduce the tensile strength of Kevlar. As such, any body armor that has Kevlar, has the Kevlar sheets covered with a thick fabric that keeps the sunrays and moisture away. The body armor also comes with very precise instructions on how to properly clean it when need be.
To protect against blunt trauma, Kevlar bulletproof vests are reinforced with steel or ceramic plates. They become armor plate carriers. However, this makes the body armor rigid, bulky, uncomfortable, and difficult to conceal. Such body armor is in most cases impractical for use by ordinary civilians, and uniformed patrol officers. While there are no restrictions on the kind of body armor one can wear, such heavy body armor is in most cases used by tactical forces while they are in high-risk environments.
The bottom line is, Kevlar by itself only makes soft body armor. Other materials such as steel, ceramic and Polyethylene are used to create armor plates that reinforce the soft body armor. Soft body armor is preferred because it is comfortable to wear and easy to conceal.
Steel Body Armor
Ancient body armor was made of steel. Imagine wearing pounds and pounds of steel clothing all over your body. This kind of armor was very bulky, and difficult to move around with. Steel is still used to make body armor, but sparingly. Today, steel is mainly used to make ballistic armor plates. It is used to manufacture armor helmets, and in armored vehicles as well.
Steel ballistic plates are arguably the most popular steel body armor products. They are used in conjunction with carrier vests, which are made of Kevlar sheets and fabric. The plates are inserted into specially designed pockets within the carriers. Steel armor plates are used to protect against heavy gunfire. The body armor combination of carrier vests and steel plates can either be rated as level III or level IV.
In any circumstance that might involve gunfire from rifles, steel ballistic plates are essential. Their main purpose is to subdue the blunt trauma. As mentioned earlier, Kevlar has the capacity to stop some rifle-fired bullets from piercing through, but the blunt force might be too much. For instance, a bullet might not pierce into your chest, but it might hit your chest with such force that it breaks your ribs. This could easily turn fatal.
Steel is a very hard and tough metal. There is no doubt when it comes to its ability to stop and subdue a bullet. One of the most impressive aspects about steel armor plates, it that they can handle multiple bullets at the same spot, unlike many ceramic plates. Only steel is deemed tough enough to stop armor piercing bullets. Most level body armor features steel armor plates. Other materials such as ceramic will easily shatter when hit by a .30 M2 armor piercing bullet.
It is an industry standard that steel armor plates are coated with multiple layers of Paxcon. Paxcon is a tough bed liner fabric. When the steel plate is hit, especially by a powerful bullet, many tiny fragments chip off of it. These fragments can be dangerous if they are not properly contained. They can easily slice through the plate carrier and clothing and pierce through your skin. They may not penetrate deep into your body tissue, but it would certainly be a painful experience. The Paxcon coat ensures these fragments are contained when the steel plate gets hit.
A major downside of steel body armor has always been its weight. Steel is a heavy material, and any body armor product that has steel in it will most likely feel bulky. As such, many civilians and uniformed patrol officers do not find it necessary. Steel also makes it difficult to conceal your bulletproof vests. As mentioned above, body armor that has steel in it will normally be rated as either level III or level IV. It is mainly common with tactical forces who are facing rifle gunfire threats.
Polyethylene Body Armor
As we mentioned earlier, PE body armor comes in as a middle ground between Kevlar and steel. PE armor plates are classified as hard body armor. They are also used in conjunction with carrier vests. They are quite ideal since they are almost as hard as steel, but a lot lighter and comfortable to wear. An ordinary PE armor plate can weight anywhere between two and five pounds. In simple terms, PE armor plates are the lightest rifle-protective plates available.
One of the most impressive aspects of PE armor plates is that they can take multiple hits. Unlike steel or ceramic plates, they do not shatter when hit. They can, therefore, take multiple hits at the same spot, and still prevent the bullets from going in. So long as the bullet threat is not above level III, PE armor plates will offer ample protection. We had mentioned earlier that PE plates work by melting as a result of the friction created by the spinning bullet, then cooling down almost immediately to trap the bullet inside.
The quality of the materials used and the manufacturing process counts for a lot when it comes to the effectiveness of PE armor plates. The UHMWPE sheets ought to bond perfectly under high pressure in order to produce quality armor plates. When perfectly bonded the plate is able to withstand multiple shots without delaminating. The plate can get hit by multiple rounds and still be protective since the impact of the bullet is limited to a small part where it lands.
The most protective PE plate is rated as level III. Currently, the mass production of PE armor plates that are rated level IV is deemed not possible. The process and materials used to produce PE armor plates are expensive. Many body armor manufacturers do not see any commercial viability in the production of level IV PE armor plates. As such, the available PE armor plates cannot stop armor piercing rounds. Even the level III PE plates are quite expensive as compared to steel and ceramic plates. They are up to 200%-300% more expensive than steel or ceramic plates. That explains why PE plates are not so popular.
The other downside of PE armor plates is that they are easily degraded by high temperatures. Take for instance military personnel, who are often times involved in combat in very hot regions. The temperatures in some of the deserts can go as high as 50oC. Such conditions would compromise the effectiveness of PE armor plates. Otherwise, PE armor plates are extremely durable.
Ceramic Armor Plates
We already mentioned ceramic armor plates a couple of times, so it is only fair that we expound a little bit more on them. They are not very popular, but there are certain instances that make them a better option compared to the rest. To begin with, ceramic plates are much lighter than steel plates and a lot cheaper than PE plates. They are also classified as hard body armor, and will in some cases offer equal protection as that provided by steel plates. Putting these aspects into consideration, they might seem like the most ideal armor plates, especially in combat situations where a pound might be the difference between surviving and dying.
However, ceramic plates have a major drawback. They cannot take multiple shots to the same spot, or precision fire. You’ve probably handled ceramic items before, and have an idea of how they shatter into pieces when they get hit. Although the ceramic armor plate will not completely shatter into pieces, the spot where it gets hit cracks badly. That plate becomes quite ineffective, and it is almost certain that the bullet will go through if you get hit at the same spot again. On the flipside, the immediate break up on impact helps to ensure the bullet is stopped. Apparently, a 7.62mm bullet can create a space of up to 3’’ on the ceramic plate when it hits it.
Ceramic plates are fragile and you must take good care of them if you must have them. They are ideal if you are sure you will not be facing heavy gunfire threats. You should replace a ceramic armor plate if it gets cracked.
The materials explored above, are the most common when in the manufacture of body armor. The most ideal material simply depends on the level of threat you are facing, and how comfortable you need to be while wearing the body armor. Kevlar stands out as the most preferred material, and many soft body armor products are made of Kevlar. It is not difficult to see why.
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