Sunday, August 9, 2020

Guest Post: UHDPE Ballistic Plates

by Seth Schuehartt

Seth is an Armed Security Professional and Consultant in Phoenix, Arizona.

Editor's Note: It was pointed out to me that in my article about ballistic armor materials, I completely neglected to mention UHDPE plates. Since I have no experience with this material and there is less information about them than with steel and ceramic, I defer to Seth in this matter.

Per the author's request, it should be noted that this post has been edited down (it was originally five pages long) for content and for brevity.   -- Erin Palette
Disclaimer: Everything I say here is true to the best of my knowledge, but I am human and am currently updating my understanding of the topic. The goal here is to pass along what I’ve learned, and even as a fairly informed consumer and professional end user, my understanding of the subject is that of a layman’s when compared to the folks who do all the testing on this stuff. There’s a lot I don’t know, but I do know enough to make an informed purchase. 
When it comes to ballistic rifle armor, you typically see ceramic and steel as the  primary component of construction. What’s new is the emergence of Ultra High Density Polyethylene (UHDPE) plates on the market.

UHDPE (henceforth just called "poly") plates are extraordinarily lightweight (5 pounds per plate) and can perform well up to NIJ Level III, having been proven extremely effective at stopping lead/copper projectiles. Unfortunately, they don't hold up very well to any sort of solid projectile, such as bonded cores and mild steel (non-AP) cores.*

However, many manufacturers offer a hybrid Ceramic/Poly style plate, essentially wrapping the ceramic in rigid Polyethylene to save weight (hybrid plates are around 6 lbs) to protect the ceramic component of the armor while offering NIJ Level IV protection. If you’re looking for a standalone Level IV plate, this construction is what I would recommend.

If you can carry the extra weight, I’d also recommend a "training" or "fitness" metal plate (it doesn’t necessarily need to have a ballistic rating) to save your chest the pain of blunt trauma after being shot, and to keep you in the fight since backface deformation (how deformed the side of armor closest to your skin becomes after being struck by a bullet) allows for potentially lethal injuries. This is the only place where steel shines, as it spreads the impact across the entire body contact-area whereas other plates basically end up with all that energy directed into a solid baseball-sized area punched into the body with broken bones not uncommon. However, that same benefit of steel can be achieved by using a fitness plate. If weight is an issue, a lighter but less effective option is what's known as a trauma pad.

* The NIJ is currently changing their standards for armor performance. This is due to steel armors failing with high velocity rounds within their threat profile, and poly armor failing to modern bonded core and exposed penetrator type projectiles. For example, a Level IV plate should hold up to any 5.56mm bullet, but M855 (the most common 5.56mm cartridge within the US military) will punch through any poly plate, and any 55 grain bullet traveling at 3000+ fps will punch through most steel plates, whereas ceramic will maintain its protection.

The new standards will be adjusted to account for these shortcomings. A notice has been disseminated to manufacturers, but I am not privy to the details of that notice. Here’s some links to get you started:

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