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Bonding technologies: needlepunching.

The needlepunching industry around the world has never been a more exciting and diverse trade. Worldwide, the needlepunching industry enjoys one of the best successes of any textile related process or industry.

In the U.S., the needlepunching sector of the nonwovens industry has always been the black sheep of the nonwovens industry. Needlepunching still has the connotation of being a slow, nontechnical technology. Internationally, however, it is interesting to note that these negative connotations relating to needlepunching are not so prevalent. This is especially true in Asian markets. The simple fact of the matter is that many U.S. companies do not fully understand the needlepunching process nor the emerging and developing markets and the companies cannot see the profitable future for those companies involved in needlepunching.

In the U.S., most so-called experts claim the needlepunching industry is growing at a level of 5-8% annually. This is a very difficult figure to guesstimate because of the fragmented nature of the U.S. needlepunching market. Internationally, the needlepunching marketplace is even more diverse. In the U.S., there are about 280 companies performing some type of needlepunching operation. In some cases, this needlepunching is an extensive part of their business while in others, the needlepunching is seldom used. A partial list of some of the products being produced on needle looms worldwide is found in Table 1.
 Table 1
 Tennis Court Surfaces Composites
Space Shuttle Exterior Tiles Blood Filters
Marine Hulls, Headliners Tennis Ball Covers
 Shoe Felts Synthetic Leather
 Blankets Carpet Underlay Pads
 Automotive Carpeting Carpeting
 Automotive Insulation Auto Trunk Liners
 Filters Interlinings
 Geotextiles Papermaker Felts
 Vinyl Substrate Felts
 Insulator Padding
Primary Carpet Backing Shoulder Padding
Fiberglass Insulation Felts Ceramic Insulation
 Fiberglass Mats Kevlar Bullet Proof Vests

The needlepunch process is illustrated in Figure 1. Needlepunched nonwovens are created by mechanically orienting and interlocking the fibers of a spunbonded or carded web. This mechanical interlocking is achieved with thousands of barbed felting needles repeatedly passing into and out of the web. The major components of the needle loom and a brief description of each are as follows:

The Needle Loom

1. The needle board. The needle board is where the needles are inserted. The needle board then fits into the needle beam that holds the needle board into place.

2. The feed roll and exit roll. These are typically driven rolls and they facilitate the web as it passes through the needle loom.

3. The bed plate and stripper plate. The web passes through two plates, a bedplate on the bottom and a stripper plate on the top. Corresponding holes are located in each plate and it is through these holes the needles pass in and out. The bed plate is the surface the fabric passes on top of as the web passes through the loom. The needles carry bundles of fiber through the bed plate holes. The stripper plate does what the name implies, it strips the fibers from the needle so the material can advance through the needle loom.

The Felting Needle

The correct felting needle can make or break the needlepunched product. The proper selection of gauge, barb depth, point type and blade shape (such as pinch blade, star blade, conical) can often give the needlepuncher the added edge he or she needs in this highly competitive industry.

The major components of the basic felting needle are as follows:

1. The crank. The crank is the 90 degree bend on the top of the needle. It locates the needle when inserted into the needle board.

2. The shank. The shank is the thickest part of the needle. The shank is that part of the needle that fits directly into the needleboard itself.

3. The intermediate blade. The intermediate blade is put on fine gauge needles to make them more flexible and somewhat easier to put inside the needleboard itself. This is typically put on 32 gauge needles and finer.

4. The blade. The blade is the working part of the needle. The blade is what passes into the web and is where the all important barbs are placed.

5. The barbs. The barbs are the most important part of the needle. It is the barb that carries and interlocks the fibers. The shape and size of the barbs can dramatically effect the needled product.

6. The point. Obviously, the point is the very tip of the needle. It is important that the point is of correct proportion and design to ensure minimal needle breakage and maximize surface appearance.

As the needle loom beam moves up and down the blades of the needles penetrate the fibrous batt. Barbs on the blade of the needle pick up fibers on the downward movement and carry these fibers the depth of the penetration. The draw roll pulls the batt through the needle loom as the needles reorient the fibers from a predominately horizontal to almost a vertical position. The more the needles penetrate the web the more dense and strong the web becomes (to a point, after which fiber damage from excessive penetrations results). In its most basic form, this is the needlepunching process.

Types of Looms

There are three basic types of needle looms in the needlepunching industry. They are:

1) The "Felting" Loom

2) The "Structuring" Loom

3) The "Random Velour" Loom

The felting looms are the type described above. These needle looms may have one to four needle boards, needle from the top, bottom or top and bottom. The primary function of this type of loom is to do interlocking of fibers resulting in a flat, one dimensional fabric. The types of products made with this process and needle loom are diverse and multi-faceted.

Structuring looms use what are called fork needles. Instead of carrying fibers into bed plate holes, the fork needles carry fiber tufts into lamella bars that extend from the entry to the exit of the needle loom (Figure 2). These fork needles carry large tufts of fibers into parallel lamella bars. These bars carry the tuft of fiber from the entry to the exit side of the loom. Depending on the orientation of the fork needle, a rib or velour surface is produced. The most popular products made with structuring looms and the fork needles include home and commercial carpets and floor mats, automotive rib and velour products, wall covering and marine products.

Random velour looms are the newest type of needle looms, having only been available since 1985. The random velour looms are used to produce velour surfaces. Unlike the structuring looms, the velour products produced by this loom are completely non-linear. It is almost impossible to tell the cross direction from the machine direction.

Unique to this needle loom is the bristle brush bed plate system. Special crown type needles or fork needles are used in this loom design. The needles push fibers into a moving brush bed plate. The fibers are carried in this brush from the entry to the exit of the loom with zero draft. This allows for the completely non-linear look, perfect for molded products. Random velour type products have been very popular in the European and Japanese automotive industry. While almost all U.S. automotive producers have the random velour machine, this type of product has yet to take off in this country. The most popular products made with this type of needle loom are almost all centered around the automotive industry.

About the author:

John Foster is executive vice president of Foster Needle Company, Manitowoc, WI, a manufacturer of felting needles with facilities in Manitowoc and Redditch, England. Mr. Foster graduated with a B.A. in Business/Communications from Carroll College in Waukesha, WI. He has written numerous articles on needlepunched nonwovens and has been a frequent speaker on needlepunching at various seminars in the industry.
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Title Annotation:Nonwoven Bonding Technologies: There's More Than One way to Bond a Web; use in production of nonwoven fabrics
Author:Foster, John
Publication:Nonwovens Industry
Date:Oct 1, 1992
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