Material Types Used for Hard Hats

Material Types Used To Make Hard Hats

Hard hats provide a helmet-like design used to protect a worker's head from impacts by blunt or sharp objects. They also deliver a protective layer that safeguards against falls.

Approximately 20 million people in the United States and millions more globally wear hard hats while working. When worn correctly, a properly constructed product delivers two protection types.

The hard shell provides resistance to penetration by sharp objects. Workers also benefit from the suspension system that lessens the pressure and impact of a localized blow by distributing the force.

Most hard hats use a network of straps that connect to a headband attached to the helmet to create the suspension effect. That design holds the hard hat's shell at least 1.25 inches (3 centimeters) away from the head.

Today's materials used for hard hats meet the current ANSI (American National Standards Institute) performance standards. When looking at older designs, you'll see that a wide variety of materials were used to create a safer working environment.

Past and Present Material Types Used for Hard Hats

Several different materials have been used to make hard hats over the past few decades. Here's a closer look at some of the most popular options.

1. High-Density Polyethylene (HDPE)

Most hard hats today are made from HDPE. That's because it is one of the best pound-for-pound plastics available for strength, durability, and environmental flexibility. [[1]]

HDPE was first made in the 1930s, and it was first used to create high-frequency radar cables. The material varies in flexibility, which is why hard hats use a high-density version to provide a protective shell.

It has excellent impact resistance ratings and performs well when exposed to chemicals.

The one issue you'll find with HDPE is that it can experience poor weathering with frequent use. That makes it a little sensitive to stress cracking. It's also not biodegradable, so it cannot be composted for natural recycling.
HDPE hard hats are among the most popular and least expensive hard hats sold today. Here are some examples:

                 

2. ABS Plastic

ABS stands for Acrylonitrile Butadiene Styrene. This material is the same foundational product that you'll find in toys, furniture, and many other items. If you purchase a thermoplastic hard hat, you're getting this material.

ABS is an amorphous and thermoplastic polymer. The name refers to the creation process where it becomes liquid at a specific temperature. Manufacturers can heat this material to its melting point, cool it, and repeat the process without significantly degrading its strength.

Since ABS plastics liquefy instead of burning at a high temperature, today's top hard hat brands can use injection molding manufacturing processes to create world-class products.

The benefits of using ABS plastic for a hard hat include its strong resistance to physical impacts and corrosive chemicals. It's quite easy to machine, and the lower melting temperature makes it useful for multiple processes.

When compared to other hard hat materials, ABS plastics are relatively inexpensive. Although polypropylene is a bit cheaper, it's not as expensive as other plastics.

There are no known carcinogens associated with ABS. It's structurally sturdy, stiff, and comfortable to wear with a well-designed suspension system.

Here are our most popular ABS plastic hard hats:

        

3. Fiberglass

Scientists began researching how fibers and resins could work together after Games Slayter, who worked at Owens-Illinois, accidentally sent a jet of compressed air at some molten glass. The fibers it produced were seen as a useful insulator. [[4]]

Fiberglass hard hats are the industry standard for mining or electrical workers. The material has a much higher temperature resistance while remaining light and durable.

If you're working in a welding foundry, you're likely putting a fiberglass hard hat on your head.

Since fiberglass can be molded into virtually any shape without an adverse impact on its mechanical strength, you can find hard hats with several different styles from today's top brands. It lasts a long time, provides workers with a low-maintenance experience, and has anti-magnetic properties.

Here's a good example of a fiberglass hard hat:

It has less rigidity than other materials, so the energy distribution from a forceful impact might not be as efficient. Most workers find fiberglass to be lighter than other options, which is helpful when managing a long shift in a physically demanding environment.

4. Ultem

Ultem is a semi-transparent high-strength plastic material. It's the brand name for polyetherimide. [[2]]

What makes this engineered material an intriguing option for hard hats is its environmental flexibility. It delivers a stiff, semi-transparent sheet that is exceptionally strong and handles a high service temperature environment.

Ultem offers hydrolysis resistance when exposed to steam or hot water, and it can also withstand repeated sterilization cycles. The material has one of the highest dielectric ratings of any thermoplastic material in today's industry.

The disadvantage of using a proprietary product like Ultem is that specific licensing or purchasing rules are often in place. That's why it's often cheaper and easier to use a standardized material when shopping for the best hard hats.

5. Molded Thermoplastic

Molded thermoplastic hard hats use melted pellets and are forced into a mold to assume their final shape, like a hard hat. It's different from thermoset molding, when the material is quickly cooled, creating a chemical change instead of a physical one to produce an irreversible process. [[3]]

Thermoplastic molding produces hard hats repetitively with a significant degree of accuracy and a high-quality surface finish. Since it delivers a high output rate, the prices for products made through this process are often lower.

The primary advantage of using this method for the wearer is the strength of the material. Thermoplastic molding typically has more durability than plastic machined components because different fillers can get added to the base material.

The thermoplastic injection project also lets manufacturers use multiple plastic types with co-injection molding for different results.

6. Bakelite Composite

This material is a type of phenolic resin. Its formal name is quite long and not so much fun to say (or type!): polyoxybenzylmethyleneglycolanhydride.

Bakelite phenolics were first commercialized in 1909. The material was relatively strong, stiff, and was easy to mold. It's even relatively possible to create different colors with it.

At one time, the production of this material exceeded that of what several plastics, including PS, PE, and PVC, experience today. It's chemically stable with good electrical properties. That made it a suitable option for the mining industry or builders.

The issue with this material for hard hats is that it isn't as strong as today's modern materials. You can still find some brands manufacturing them. Look for options with an ANSI Type 1 rating for the best results.

Since it can withstand significant temperatures, you see this hard hat option used more often in firefighting capacities than for building, mining, or other construction tasks.

7. Metal

Edward Bullard brought home a steel helmet from World War I. It wasn't just a souvenir from his time as a doughboy. That design would serve as the cornerstone of a revolution in industrial safety. [[5]]

Bullard's father had sold safety equipment to copper and gold miners for more than two decades. They all wore hats similar to a baseball cap, with a hard-leather brim providing minimal protection from falling objects.

In 1919, Bullard patented his "hard-boiled hat." It was made from a steam-based process that combined resin and canvas, with several layers glued together and molded into shape. The military approached him to develop the first hard hats for shipyard workers that same year.

It was then that Bullard started working on the first internal suspension system to make the hard hats more comfortable to wear.

In 1933, Bullard helped the Golden Gate Bridge project create a special hard hat for sandblasters to use. It covered their faces while offering a window to see and a pumping system for fresh air.

In 1938, the first aluminum hard hats were introduced, offering a lightweight wearing experience and more durability. Since they couldn't be used around electrical installations, more innovation in materials became necessary.

8. Polypropylene

Polypropylene is a popular material for hard hats because it can also successfully go through the injection molding process. Even though it has a semi-crystalline nature, the low-melt viscosity ensures that it flows nicely when liquefied.

That crystalline structure allows the material to have significant flexural strength. It also delivers excellent chemical resistance across a broad range of different acids and bases.

The impact strength is also comparable to other options in the hard hat industry.

The one big advantage that polypropylene offers is its repairability after damage. It also delivers above-average resistance to electricity.

Since it has a low annealing temperature, the material starts deforming when placed in a high-temperature environment.

The downside of using polypropylene is that it can be susceptible to UV degradation. It delivers below-average resistance to aromatics and chlorinated solvents, and there is some susceptibility to oxidation.

9. Carbon Fiber

Carbon fiber hard hats come with several advantages to consider. [[6]]

This material delivers high tensile strength and stiffness, a lightweight wearing experience, and exceptional chemical resistance. It offers a low thermal expansion rating and a higher temperature tolerance.

The properties found in carbon fiber are similar to that of steel, even though the weight is closer to most plastics. That means it offers one of the best strength-to-weight ratios in the industry today.

A carbon fiber shell naturally dampens any surrounding energy. That allows it to cope well with vibration and impacts. It?s flexible enough to shape during the manufacturing process easily while providing excellent stress resistance.

Those benefits come with a significant jump in price. When comparing a carbon fiber hard hat to one made from HDPE or ABS, you could end up paying 17 times more for the protection you receive.

Comparing HDPE vs. ABS

Most affordable hard hats today are made from HDPE or ABS. Both options are considered thermoplastics.

Each has unique material properties worth considering. A direct comparison of each can let you know which one is more appropriate for your current situation. [[7]]

Material Property

HDPE

ABS Plastic

Density (g/cm3)

1.0 to 1.3

1.0 to 1.4

Percentage of Elongation at Break

2.5 to 100

3.5 to 50

Flexural Modulus (GPa)

4.0 to 7.5

2.1 to 7.6

Impact Strength (Notched Izod J/m)

50 to 260

70 to 370

Strength to Weight (Axial/Points)

6.9 to 17

10 to 22

Strength to Weight (Bending/Points)

24 to 37

19 to 32

Tensile Strength: (UTS, MPa)

24 to 80

37 to 110

Since the materials are relatively similar, one of the best comparison points to use when shopping for a new hard hat is its suspension. The standard option uses a four-point ratchet design, but Pyramex delivers a six-point system that offers more protection and comfort.

With a six-point suspension, any potential impact gets spread more evenly across the head. When you have an ABS product with a Class E electrical rating, you have a proof-tested safety asset that handles up to 20,000 volts.

You can also find HDPE hard hats with the same Class E rating.

The one issue that some workers might encounter with an ABS hard hat is how quickly the material scratches. Although that doesn't affect how the product performs, it does change how it looks.

When strength is your primary concern, an injection-molded fiberglass hard hat is eight times stronger than these materials. Some fiberglass designs even come with an eight-point suspension system.

What Is the Best Hard Hat Material for Me?

Hard hats are a must-have item in many environments. They keep you safe from the various risks you potentially face when working.

Most hard hats today come in all the standard colors. When you're shopping for a new product, here are the unspoken rules that many workplaces follow.

  • Yellow hard hats are typically worn by contractors or general workers, such as equipment operators, carpenters, roofers, and laborers.
  • Shift managers and engineers typically wear white.
  • Technical workers usually wear a blue hard hat, although orange is often legally required when working along a street or highway.
  • Safety inspectors, visitors, and sometimes probationary workers put on green.
  • The vast majority of hard hats used in the field these days are white in color.

In the mining industry, it's usually a legal requirement to wear a colored hat based on your experience.

With all the different material types available today, selecting one that fits your specific needs can be challenging. Reviewing each option's strengths, benefits, and weaknesses will make it easier to find an appropriate choice for your current and future needs.



[[1]] https://www.acmeplastics.com/what-is-hdpe

[[2]] https://www.curbellplastics.com/Research-Solutions/Materials/Ultem

[[3]] https://msicarolina.com/2016/05/06/what-is-thermoplastic-molding/

[[4]] https://www.sciencedirect.com/topics/engineering/bakelite

[[5]] https://www.smithsonianmag.com/innovation/history-hard-hat-180974238/

[[6]] https://www.materialsciencejournal.org/vol14no1/carbon-fibres-production-properties-and-potential-use/

[[7]] https://www.makeitfrom.com/compare/Acrylonitrile-Butadiene-Styrene-ABS/High-Density-Polyethylene-HDPE

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