What Makes Military Wheels Different and How are They Made | Manufacturing Industries | advancedmanufacturing.org

Wars can’t be won on flat tires. Neither can the military complete its often life-or-death missions if the wheels that carry these tires aren’t rugged yet lightweight, easy to maintain and repair, and able to withstand the rigors of combat. This helps explain why military wheel manufacturers must comply with a number of quality and performance standards, among them SAE J1992_201906: Wheels/Rims - Military Vehicles Test Procedures and Performance Requirements, and SAE J2014-2022: Pneumatic Tire/Wheel/Runflat Assembly Qualifications for Military Tactical Wheeled Vehicles.

In fact, a quick search of the SAE International Standards returns a dozen or so similar specifications, each addressing a certain set of requirements in this demanding-yet-often-overlooked market sector. With that are numerous country-specific guidelines, such as those provided by Europe’s Finabel and TÜV Rheinland, as well as vehicle manufacturers’ internal quality standards.

An aluminum wheel blank emerges from the rotary forge, ready for flow forming.

Some truly gigantic companies are making these military vehicles, all of which consume huge numbers of wheels annually. In the United States, there’s General Dynamic Land Systems, Oshkosh Defense, BAE Systems and AM General, to name a few. Because European and Asian countries must also defend themselves, there’s Rheinmetall of Germany, Nexter in France, Israel’s Elbit Systems Ltd., Hanwha Defense in South Korea, Samtel Avionics Ltd. of India, DCD Group of South Africa—and the list goes on.

As stated at the outset, it’s serious business. Wikipedia notes that an astounding 1,665 models of military vehicles have been produced worldwide since war first became both mechanized and mobile. Many of these are no longer in service, although about 200 types of U.S. battle tanks, armored combat support and light-utility vehicles, self-propelled artillery and all manner of earthmoving and construction equipment are still rolling along.

According to the data gathering firm Statista, this equates to nearly 400,000 tracked or wheeled ground-combat vehicles, with an additional 200,000 or so deployed in NATO countries France, Germany and Italy. Considering that most have at least four wheels and some have as many as 30 per vehicle (such as the M1 Abrams Main Battle Tank), that’s a lot of wheels. The question then becomes: who’s making all of them, and how do they differ from the chrome wheels you put on your vintage Z28 Camaro or the oversized RTX Black Widows sitting on the family SUV?

The answer to the first question is Advanced Structural Technologies. Not all of them, of course—producing that many wheels would be a Herculean feat—but in addition to flow-formed and rotary-forged rocket components, we’ve been making wheels and wheel blanks since the company’s founding in 1998.

Some of these are for the M1 Abrams, but there’s also the M2 Bradley Fighting Vehicle, the M88 HERCULES (Heavy Equipment Recovery Combat Utility Lifting Extraction System), the M109 Paladin 155-mm howitzer, the next-generation armored multipurpose vehicle and many others.

Despite this success, it’s a multibillion-dollar industry, and we’re not the only wheel-blank supplier in the business. This leads to more questions: What makes military wheels different and how are they made?

For starters, most of the current-generation of military vehicles utilize wheels of a two-piece construction, consisting of inner and outer wheels that must be bolted together before use. This is to accommodate a run-flat mechanism, as alluded to in SAE J2014-2022. This is typically a donut made of hard rubber or plastic that fits around the two pieces, either as a single piece that slips over the wheel assembly or a clamshell-style unit that bolts in place.

Regardless of the design, a run-flat wheel does just what its name suggests: It allows the vehicle and its crew to remain in action until they can get somewhere safe to change a flat tire. It’s the same logic used in some high-end passenger cars, albeit with far higher stakes than arriving home late for dinner.

Unsurprisingly, military wheels are also more rugged than their commercial counterparts, with a thicker hub and rim that can carry seriously heavy loads. Some are designed to support weights in excess of 10,000 lbs and do so at relatively high speeds—the 60-ton M1A2 Abrams tank, for example, can achieve 45 mph on hard surfaces and carries enough fuel to travel nearly 300 miles.

What might surprise you is that the wheels used on military vehicles are often made of aluminum, not steel or a nickel-based superalloy as one might expect. This is done for the same reasons that passenger cars and trucks use this lightweight alloy—fuel economy, both for the vehicle itself and the plane, train or ship that transports it to the military base or staging area.

That said, the aluminum used in these wheels is generally an aerospace-grade, such as 7075-T6 and 2024-T3, not the cast 6061-T6 found in commercial wheels. Both have strength-to-weight ratios much higher than steel (and are more resistant to corrosion) and can withstand battlefield-level abuse without failure.

That brings up another point: Military-grade wheels (at least those made at AST) aren’t cast but rather forged and spun. This makes them stronger still, especially when a rotary forging process is used. Like spin forming, it serves to tighten and align the metal’s microscopic grain structure, and is the same technology used to manufacture rocket componentry.

The process begins with long bars of aluminum billet bought directly from one of several mills. These are band-sawed into precise lengths and then heated to about 900° F (482 °C) before being sent to a rotary forging press.

The rotary forging process pivoting upper die generates superior metal flow compared to the drop forged alternative.

Depending on the final workpiece, this creates what is essentially a large donut or disk that we then take to a spinning machine, where a series of rollers force it into a near-net shape. Then the workpiece is heat-treated once more to eliminate any stress and increase the aluminum’s hardness before finish machining. It’s not unlike spinning a pot or bowl on a potter’s wheel, but using metal hands and a material that is far less malleable than clay.

The forging and spinning processes impart a finer, more consistent grain flow to the wheel, unlike those that are cast or drop forged. The result is a wheel with upwards of 20% greater tensile strength, without any of the inclusions or porosity that can lead to failure. Maybe that’s why we routinely produce more than 3,000 rotary forged wheels per month.

Some of these are being installed on Ford F450 and F550 pickup trucks, which are sent to Poland for outfitting with rocket and drone launchers, then railed to Ukraine to defend against Russian forces. We also see high demand for wheels that will end up on the Humvee replacement, the Joint Light Tactical Vehicle), large numbers of wheel upgrades to legacy vehicles and several new programs that remain under wraps.

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