NON-WOVEN NEEDLE FELTS

DLTT  is specialized in synthetic Fiber materials for higher standard and  environment friendly results. There are a few advantages of using  synthetic needle felt that include broader temperature, chemical,  abrasion and cut resistance, higher tensile strength and elongation, as  well as compliance with different fire classes. Felted fabrics are  generally used with higher energy cleaning systems such as pulse-jet  cleaning, systems that filter more air per cloth area (higher  air-to-cloth ratio) than a shaker or reverse-air unit. Together with our  partners we process a wide variety of synthetic fibers, either to  produce medias for cement plants, wastewater treatment, water supply,  chemical processing, coating processes, or even for food or pharmacy  industry. By offering you a wide range of spare parts and technical  equipment, DLTT can deliver high quality synthetic needle felts,  matching almost any challenge you can face in your technical separation  or filtration projects. 

Due  to our large experience and technical resources, we are able to deliver  customized products according to specific customer needs covering the  value chain of the filter manufacturer. To properly suit the needs of  different fields, the products can be customized according to the  client’s demands, DLTT can even provide professional advice on which  option suits your working condition best. Feel free to reach us  regarding recommendations or support through our website’s Contact section. 

Felted filters are made by needle punching fibers onto a woven backing known as scrim. Felted filters are composed of randomly placed fibers compressed into a mat and attached to loosely woven backing material, as opposed to the repeated pattern of woven filters. The felts are attached to the scrim by methods such as chemical, heat, resin, or stitch-bonding. 

In order to collect fine particles, felted filters depend on a lesser degree on the initial dust deposits than woven filters do. The felted filters are generally 2 to 3 times thicker than woven filters. Each individual randomly oriented fiber acts as a target for particle capture by impaction and interception.

DLTT mainly provide felts in the following synthetic fibers: Polyester, PTFE, PP, PPS, Aramid, Acryl, Fiberglass. Each of them provide excellent technical properties in the final result.

Polyester: Due to its favorable price, versatility and great performance ratio, polyester is the most commonly used fiber in filter media, especially in dust collection segments. 

PTFE: made from 100% PTFE fiber stamped in a three-dimensional structure, this fiber, used as filter media, has properties such as excellent flexibility, high tensile strength, creep resistance, high and low temperature resistance, corrosion resistance and anti-aging characteristics.

PP: PP fibers has excellent resistance to hydrolysis, acids and alkalis, a smooth surface, with more defined pore sizes and good air permeability. It also presents a lower fiber output, lower density, and high mechanical properties.

PPS: PPS felt is one of the main filter materials able to process the high temperatures. It can also maintain the intensity and inherently carry chemistry, preserving a good filtration performance even in the most hideous environments.

Aramid: Aramid’s high thermostable performance enables it to work well under acid-based conditions at 204°C for a long time. Its high performance in terms of portability and foldability helps to extend the life of the filter material. The high ventilation performance reduces the pressure drop of the dust collector, saves energy and associated costs. 

Acryl: This type of needle felt has good acid and alkali resistance, anti-oxidation and hydrolysis resistance. It also has great mechanical properties, an optimal heat stability in both dry and wet conditions, and exceptional resistance to light, weather, mold and bacteria.

Fiberglass: this is a high temperature resistant filter material with reasonable structure and excellent performance. Compared to other high-temperature chemical fiber felt, it has the advantage of a good price-performance ratio. 

If you want to know more about materials proprieties, visit ou Technical Information webpage!

In order to meet your requirements, we can also offer PTFE or Fiber glass Filter-bags and Micron Filter-bags for liquid separation. Furthermore we can deliver a wide range of high efficiency dedusting filter cartridges, to fulfill the highest industry standards. 

Air Permeability: Permeability is the measure of the ability of a porous material to transmit air or fluids, which depends on the porosity of the fabric. The porosity is largely determined by the tightness of the fabric compression, to its geometric structure as well as to the path of streamlines for flow through the structure. The most common measurements for air permeability are L/m2/sec@200pa; L/dm2/min@200pa and m3/m2/min@200pa. 

Weight: The felt weight is the outcome of how a fabric has been compressed, its finish and specially the fiber type. 

Thickness: yarn should be as fine as possible depending on the required strength of seam. Thicker threads have generally greater strength, given the same fibre content and yarn structure. On the other hand, threads tend to blend into the fabric surface and are less subject to abrasion. Finer yarns perform better with finer needles and produce less fabric distortion. The felted filters are generally 2 to 3 times thicker than woven filters.

Temperature and Chemical properties (Alkali / Acid / Base): in order to maintain the efficiency properties of a synthetic fabric it is important to pick the adequate fiber that  matches the filtering process conditions. 

Cut and Abrasion resistance: the felts capacity to resist rubbing against its surface, or to cutting interactions in the filtering environment. 

Breaking strength: the tension at which a thread breaks, expressed in grams or kilograms.

Elongation at break: the amount by which a thread is extended at its breaking point expressed as a percentage of its original length.

In order to provide a more adequate filtering media that suits you working conditions, the felts can have applied anti-static, chemical or thermal resistant, flame retardant, oil and water repellent finishing. 

Calendaring: which pushes the surface fibers down onto the body of the filter medium. This is done to increase surface life and dimensional stability and to give a more uniform surface to bag fabric.

Pressing: also known as Glazing. A high pressure is applied of the fiber at elevated temperatures. Glazing improves the mechanical stability of the filter and helps reduce bag shrinkage that occurs from prolonged use.

Singeing: it is done by passing the filter material over an open flame, removing any straggly surface fibers. This provides a more uniform surface.

Felted bags should not be used in high humidity situations, especially if the particles filtered have an affinity to absorb moisture. Clogging or blinding could result in such situations. Three failure mechanisms can shorten the operating life of a bag: they are related to thermal durability, abrasion, and chemical attack. The main variable is the upper temperature limit of the fabric, or thermal durability, it is process temperature that will determine which fabric material should be used for dust collection. Another problem frequently encountered in filtering operation is abrasion. Bag abrasion can result from bags rubbing against each other. From the type of bag cleaning used, or where dust enters the bag and contacts with the fabric material, a proper fabric selection and good process operating practices can help eliminate bag deterioration.

High temperature  PTFE Sewing Thread Nähgarn Sewing Yarn Dtex denier filter bag manufacturing stitching