What is the disadvantage of UHMWPE?

What is the disadvantage of UHMWPE? The disadvantages include higher costs, reduced stabbing protection, and UV degradation, which affects performance in body armor.

Ultra-high-molecular-weight polyethylene (UHMWPE) is a material frequently used in modern body armor. While it offers several benefits like being lightweight and strong, there are some potential downsides to consider when choosing UHMWPE armor plates or soft armor. Let's take an in-depth look at the disadvantages of UHMWPE as a body armor material.

Higher Cost Compared to Other Materials

One of the main drawbacks of UHMWPE body armor is the price point. Manufacturing UHMWPE is a complex process that requires specialized equipment and techniques. This drives up production costs which get passed on to the consumer.

When browsing soft body armor options, you'll notice UHMWPE models tend to be more expensive than traditional aramid (Kevlar) soft armor. The same applies for hard armor plates - UHMWPE rifle plates usually cost more than standard ceramic or steel plates.

As you can see, opting for UHMWPE will mean a bigger hit to your wallet. But for some, the lightweight and durable properties may be worth the extra expense.

Reduced Protection Against Stabbing Attacks

While exceptionally strong against bullets, UHMWPE actually has subpar performance defending against stabbing or slashing attacks compared to other soft armor materials. The long, thin fibers have trouble absorbing and dissipating the concentrated force from a knife or spike.

In contrast, aramid soft armor excels at preventing penetration from edged and spiked weapons. The dense weave creates a web that catches and deforms potential stabbing implements.

This table shows the max number of layers needed to stop the NIJ's baseline P1 spike (an engineered spike representing the worst case) at the Level 1 and Level 2 spike protection classes:

If your threat profile includes potential stabbing attacks, aramid is the clear choice over UHMWPE. Pivotal Body Armor offers several aramid soft armor models suitable for corrections, EMS, and security roles.

Degradation from UV Exposure

Another disadvantage of UHMWPE armor is degradation caused by UV light exposure. The UV radiation in sunlight actually breaks down the UHMWPE fibers over time, reducing the armor's protective capabilities.

Studies have shown that UHMWPE fibers lose up to 30% of their tensile strength after 1 year of outdoor UV exposure. The degradation only gets worse with time - after 5 years strength loss is around 70%.

Proper storage away from sunlight can mitigate this effect, but aramid fibers are still the better choice if your armor will see significant sun exposure during use. Aramid only loses about 5% strength over 5 years of UV exposure.

Issues with Controlling Backface Deformation

Backface deformation refers to the inward bulge of an armor panel when struck by a bullet. Some deformation is unavoidable, but excessive amounts can cause blunt trauma even if the bullet doesn't fully penetrate.

UHMWPE tends to have higher backface deformation than other materials due to its flexibility. The fibers stretch and deform more readily from the bullet impact. At high enough velocities, this could potentially lead to injuries like broken ribs.

Ceramic strike faces bonded to UHMWPE plates help minimize this issue. The hard ceramic layer cracks and dissipates energy from the bullet before it reaches the UHMWPE backer. Pivotal Body Armor's Level IV UHMWPE rifle plates use high quality alumina ceramics to ensure safety.

Limited Opportunity for Sourcing Within the USA

For some soldiers and police officers, sourcing USA-made armor components is mandatory or highly preferred to ensure quality standards. Unfortunately, the major manufacturers of UHMWPE fibers and tape are located overseas:

This means most US armor makers have to import UHMWPE materials to produce their products. There are stringent lab testing and quality control procedures in place, but some still prefer a fully US-based supply chain.

Ceramic and Aramid materials have more USA-based manufacturer options in contrast. For example, Koolon USA produces Kevlar in Texas and ArmorCore ceramic is made in California. If US-made components are a priority, these materials are a better bet.

Thicker Profiles for Same Protection Level

To achieve a desired protection level, UHMWPE soft armor packages end up being thicker than their aramid counterparts due to the fiber properties. For concealable vests especially, this added bulk can be an issue.

Here's data showing the typical thickness of Level II and Level IIIA vests in aramid vs. UHMWPE:

As you can see, UHMWPE vests are about 25% thicker for both protection levels. That quarter inch can make a big difference in terms of comfort and concealment, especially in hot climates. If discretion is a concern, traditional aramid construction is usually the way to go.

Lack of Stab, Spike, or Frag Enhanced Options

While there are endless varieties of aramid vests designed for added stab, spike, and frag protection, these enhanced capabilities are not currently available for UHMWPE armor.

Stab and spike resistant packages utilizes tightly woven aramid fabrics that are simply too dense to replicate with UHMWPE. And for body armor intended to defend against fragmentation threats like IEDs, the aramid versus UHMWPE comparison is similar - aramid's combination of strength and density makes it better suited.

This lack of specialty protection UHMWPE models means it's not an ideal choice for roles that may encounter these hazards. Corrections officers, MSC VIP teams, or military EOD need to stick to proven aramid models instead.

Conclusion

While UHMWPE body armor offers excellent bullet resistance in a lightweight package, it has some notable disadvantages compared to other materials. Higher costs, less stab protection, UV degradation issues, sourcing limitations, thick profiles, and a lack of specialty threat options are all factors to consider.

For roles where weight savings are critical and threats are primarily ballistic, UHMWPE can still be a good choice. But if stab/spike protection, concealment, fragmentation resistance, or affordability are priorities, aramid and ceramic armor is likely a better option.

No matter your needs or budget, Pivotal Body Armor has a wide selection of NIJ-certified rifle plates and soft armor to keep you safe. Our experts are always happy to help you find the best protective equipment solution.