SAE industrial felt, or technical felt, is nonwoven wool felt used in technical applications. There are two methods of manufacturing industrial felt: wet felting or dry needle punch felting.
Technical felts are produced in a variety of thicknesses, densities, and compositions to meet a wide range of needs. The SAE, formerly known as the Society of Automotive Engineers, mandates the standards of measurements applied to nonwoven wool felts used in:
At Bouckaert, we custom manufacture our SAE industrial felt using the needle punch method. Before discussing the differences between manufacturing methods, here are the characteristics of SAE felts and nonwoven wool felts in general.
Characteristics of Industrial Wool Felt
Felt is a versatile fabric explicitly engineered for high-pressure applications in specialized industries. With the natural benefits of using wool fiber (click here for our previous post on wool felt usages), here are some of the advantages to using industrial wool felt:
Maintains its physical properties as it wears
Highly absorbent and moisture-wicking (will seal out lubricants and oil)
Sound and vibration dampening
Does not ravel or fray
Resistant to wear and tear
Acts as a filtration system (gas and oil applications)
Excellent padding for moving parts in machinery
Natural fire-retardant properties
Industrial applications such as these require high levels of aversion to abrasion, oil and grease absorption, and wear and tear. To ensure the best application results, SAE felts are classified by their density, wool content, and durability.
Density: Each grade of SAE felt ranges from hardest to most pliable, the main differing characteristic between felt grades. The thickness of pressed wool felt is controlled by the amount of pressure or needling applied during the manufacturing process. The denser the felt, the better it will retain its shape against the physical environment.
Wool content: Each grade of SAE felt is (usually) a combination of raw wool fibers and polyester fiber but additional materials such as cotton, rayon/viscose, synthetic, or plant fibers can be used instead. These “filler” materials are added to create a particular characteristic to the final product that can not be achieved by wool and/or polyester alone.
Durability: During the manufacturing process, the more pressure/needling applied (we will get into this in the next segment), the denser the felt will be. Durability relies, in part, on the amount of densification.
To note, the color of SAE industrial felts will vary. Since the wool used is natural and undyed, there is no way to control color consistency from lot to lot. There are also strict tolerance requirements based on wool content and density combined. The shape of wool can change naturally (depending on temperature) or manually (from cutting the material); density and wool content need to be adjusted to consider tolerance issues.
The Differences in Manufacturing
Wet Felting VS Dry Needle Punch Felting
All technical felts are produced under the same specs; the difference lies in the manufacturing process. Despite these “technical” differences, both processes in making SAE grade felt start the same way.
The wool fiber is first cleaned and blended with any additional synthetic materials before the carding process. The carding machine disentangles and mixes the fibers together to create a uniform web, aligning the individual fibers into a singular direction. Several of these webs are layered in alternating directions on a machine called a cross-lapper to build-up to the weight of the desired finished felt. This layered material will be much thicker (and less dense) than the finished product as it has not been densified yet. This material is referred to as a batt.
The wet felting manufacturing process is known as the more “traditional” way of producing nonwoven felts. It uses heat, moisture, and pressure to mat and densify the fiber together.
The batts are wetted with hot water and fed into a plate hardener. The plate hardener applies vibrational pressure to the wetted material using rollers to help the fibers interlock together. The hot water, added acid, and pressure eventually cause the batts to shrink down in size, creating the densely matted fibers of a pressed felt.
The wet felt is left with a sulfuric acid residue that is then neutralized in tanks filled with sodium chloride (soda ash) and warm water solution. Once the felt is neutralized, it goes through a refulling machine to smooth out any irregularities on the surface. The felt must then be dried either in a dryer or oven or hung and stretched in a drying room.
Needle Punch Method (Dry Needle Felting)
Here at BIT, we manufacture our SAE grade felts using the needle punch method. Needle punched SAE felt is marked with an “N” for “needled in the official designation (example F-7N). Here’s the difference in manufacturing:
As the name suggests, dry needle punch felting eliminates the use of moisture. Instead, the batts enter a needle loom; a precise machine that uses thousands of barbed needles mounted on a needle board to pierce the layered webs of fiber. The repeated punching of the needles entangles the fibers together to create the thick, dense felt.
Depending on the desired density, some needle punched SAE felts will then go through a heated press to further densify the material. Read more in-depth on the needle punch method here.
So Why Use Needle Punched Felt Vs A Pressed Felt for your SAE Needs?
The Pros and Cons of Needle Punched SAE Felt Vs Pressed SAE Felt
The use of chemicals in wet pressed felts gives the advantage of creating a smoother finish that allows the material to hold its shape better as it wears. The upside for needle punched felt is its economical and eco-friendly benefits; eliminating the use of harsh elements makes a cleaner production line that is more cost and time effective.
For exceptional sound insulation, needle punched felt is the go-to choice for acoustic paneling needs. But if there is one thing to remember when choosing between a wet felt or a needle punch felt, it is that both are produced under the same specs mandated by the SAE. The performance of needle punch felt is not compromised because of its manufacturing process.
Want to know how BIT can add value to your business by providing custom manufactured SAE grade industrial felts? Get in touch today!
Wool is a unique all-natural fiber with qualities that outshine many of its synthetic alternatives. 60% of all wool is used in the apparel industry, but wool felt is widely used in industrial applications. It is especially used in thermal insulation, acoustical insulation, gasket materials, and even saddle pads.
A Brief History of Wool
Humans first began domesticating sheep in Mesopotamia between 11000 and 8000 BC. Sheep were first bred for their meat, skin, and milk to solve the basic human needs of shelter and food. It was not until around 4000 BC that sheep began being bred for their wool.
As the wool trade became profitable, the migration of sheep trickled from Asia to North Africa and Europe. Sheep arrived in America with Christopher Columbus and then by the British Colonies to Virginia in early 1600.
Today, wool is used in a variety of ways from clothing to carpets to industrial applications.
BIT is the largest manufacturer of industrial felt products in North America. We use the technical felting process of needling to produce our wool felt.
Needle-punching takes loose fibers and joins them together using a needle loom full of barbed needles. The needles move up and down through the fibers to mechanically entangle them.
Wool’s durability and long-lasting properties surpass those of its synthetic alternatives. Here is why:
Flame and melt resistant. Wool requires more oxygen than is present in the air to ignite.
Retains its shape due to its natural “crimp” texture that allows for elasticity, durability, and shape memory.
Water repellent: wool can absorb large quantities of water without feeling wet.
Excellent insulator against cold, heat, sound, and vibration.
Resistant to wear and tear.
Anti-Microbial; wool will not support mold growth.
Indoor environment regulation: Wool will almost act like a natural HVAC filter, purifying indoor air by absorbing noxious gases and regulating free moisture in the air.
100% natural, renewable and sustainable. It naturally decomposes in soil releasing nutrients back into the air.
Wool felt is manufactured in a variety of thicknesses, densities, and compositions. The most common wool felts are defined by SAE specifications. The SAE, which began as the Society of Automotive Engineers, sets a standard of requirements applied to felts that require higher durability and resistance to abrasion and wear.
Here are 7 markets where nonwoven wool felt is used.
Wool Felt and Its Industrial Uses
Green Roof and Agricultural Felt
Wool’s water-resistant properties (wool can absorb up to 30% of its weight in water) allow for permittivity and free water flow. This makes industrial nonwoven wool felts a perfect match for the green roof industry.
A green roof is any roof or wall that is partially or wholly covered with vegetation and a growing medium (a soil replacement such as nonwoven wool felt), planted over a waterproof membrane. In certain environments, using soil as the main growing medium is difficult. In this scenario, needle-punch felts act as drainage panels and facilitate the distribution and storage of water within the root zone as a “soilless” growing media.
A gasket is a mechanical seal that prevents leakage from or into joined objects while under compression. Able to perform in all kinds of environments and found in virtually every industry from manufacturing to mining, oil and gas, to automotive, and others, gaskets help industry function.
Its fire-retardant properties help insulate against heat in these high-pressure situations. Simultaneously, wool can stand up against consistent oil exposure all while still maintaining its shape.
Boot liners and Accessories
Boot liners, whether it be for hiking shoes, rain boots, or anything in between, provide an extra layer of protection against a variety of weather conditions.
Nonwoven wool felt for boot liners will keep you warm without overheating in cold environments and keep out moisture in wet environments, making them a comfortable option for any situation. Unlike fleece or synthetic fiber-based liners, wool is antimicrobial making it odor-resistant even with long wears. It will naturally conform to the shape of the foot over time.
The same principles apply to fashion bags and totes. Using a nonwoven felt benefits the design of the piece while keeping it safe against the elements.
Used as a buffer between the saddle and the horse, a saddle pad, or blanket, is a must-have for any horse and rider. It offers an extra layer of shock absorption, increases the horse’s comfort, and improves saddle balance for the rider.
Nonwoven wool felt’s natural wicking properties keep the saddle pad cleaner and the horse cooler. Its multifunctional purpose of creating comfort for the horse and cleanliness of the saddle makes it essential for the rider.
Carpeting and Interior Needs
While a pricier option for under carpet padding, wool felt has many advantages over traditional foam or even synthetic needle punch felt pad.
The thermal insulation properties of wool make them a great energy-saving option for any building while also creating comfort for the buildings’ occupants. Also and perhaps the primary advantage is in wool’s ability to help maintain a healthier indoor environment by absorbing odors and other noxious gasses (VOCs). Even in unventilated circumstance, it helps aid in indoor humidity control and temperature regulation.
To sum it up, nonwoven wool felt is key to the comfort, design, and overall safety of indoor environments.
Felt Dryer Seals
Dryer seals are vital to the proper functioning of a clothes dryer by preventing clothing from falling between the drum and the dryer cabinet. It maintains a certain level of heat inside the drum which reduces friction between the metal parts that come in direct contact with each other.
Wool is resilient, durable, and holds higher natural fire-retardant properties than those of synthetic fibers. As a result, it takes higher temperatures for wool to ignite making it an obvious choice for dryer seals.
Interior Design: Decorative Design Felt and Acoustic Paneling
The best option for improving sound quality within a space is acoustic treatments. Acoustic treatment mitigate sound within a space by reducing reverb and echo as opposed to soundproofing which keeps unwanted noise from going in or out. Acoustic panels range from wall and floor coverings, hanging panels, baffles, desk dividers, and tiling while other acoustic treatments include soft surfaces and wraps.
Ten years ago, materials used to absorb sound were limited to foams, fiberglass, and other soft fabrics. Now with the use of nonwoven wool felt, you can achieve a balance of design and acoustic value from texture, saturated color (due to its ability to dye well), and take advantage of its natural acoustical dampening properties when used in acoustic paneling. They are also more cost-effective and lighter weight (making for easier do it yourself installation).
From virgin wool straight from the sheep to recycled fibers, we utilize the advantages of wool by custom manufacturing wool felt and wool blend felts of various grades, densities, and blend contents to match your specific needs. As the leader in the manufacturing of nonwoven technical felts in North America, we know there is not a one size fits all answer. We work with you from conception to completion.
Have questions or want to learn more about us? Contact us today.