Needlepunched Nonwovens

B
asically, five technologies are applied to form nonwovens. In this context, needlepunched
nonwovens – also called needle felts – are still the most important technology for transforming
fibers into a fabric. The estimated global share of needlepunched nonwovens is 30 percent.
Needlepunching is a very traditional method of forming nonwovens and is especially suitable in
terms of flexibility, quality and product diversity.

Bonding using needling requires no water and consumes little energy. It is a
high-performance technology realizing high throughput speeds exceeding 150 meters per minute,
allowing universal applications, a high degree of automation and a high production efficiency with
low personnel requirements. The biggest textile machines in the world are needle looms for needling
paper machine felts. Their working widths are up to 16 meters, and their total weight is about 750
tons. Needlepunching is an ecologically friendly technology, as it permits the use of recycled
material including that from polyethylene terephthalate bottles and regenerated fibers from
apparel, as well as natural fibers. It also offers great savings potential and has a bright future.

Flexible Technology

Today, there are numerous designs for needling machines. Machines having just one needle
board and a low needle density needle the web from one side only, either from the bottom or the
top. The production speed increases in direct relation to the number in use. Depending on the end
product, a production line can be equipped with a series of different types of machines with
alternating needling directions. A complete punching line is equipped with different machine
sections, preneedling, intermediate needling and finish-needling.

Fiber Selection Essential

As mentioned in recent issues of

Textile World Asia
, there are two basic methods to form a nonwoven; dry and wet. Needle felts use a dry method,
just like spunbonds. No water is required to form a batt made from natural or man-made fibers, or
even from glass fibers. It is very significant that reclaimed fibers from any kind of recycled
material can be used for the products. Of course, the selected fibers to be processed have a direct
impact on the overall quality and properties of the end product. These fibers may vary from short
to long fibers to continuous fibers, as in spunbond. All fiber finenesses ranging from 1 to 200
decitex, and all weights from 30 to 3,000 grams per square meter (g/m2) may be processed, which
makes needlepunching a very universal and flexible production technology.

The basic work to form a needlepunched nonwoven occurs in its initial stages, similar to
spinning. After opening and mixing, the fibers are cleaned and carded. Here is the difference: the
web is processed into either a yarn or a nonwoven. However, the web formation can be executed
either aerodynamically or mechanically. With aerodynamic technology, only random-laid webs are
possible. Mechanical formation is much more flexible, and the webs can be laid randomly, crosslaid
or parallel. The web formation process determines the characteristics and performance of the
finished nonwoven. Web bonding can be executed in three different ways: chemically, thermally or
mechanically. Needlepunching is a mechanical technology.

The first patents were given in the 1880s. In 1829, it already was possible to process
fibers like jute, sisal and animal hair. Over the years, technology has improved constantly, and
today, two of the major players in the field of needlepunched nonwovens are Germany-based Dilo
Group and France-based NSC nonwoven (Asselin-Thibeau).

Dilo Group

Dilo Group – with its member companies Dilo Temafa, Dilo Spinnbau, Dilo Machines and Dilo
Systems – is one of the leading suppliers of complete nonwovens lines. Dilo Systems engineers the
lines including production calculation and quality definition in a coordinated way to be ready as a
turnkey installation that offers commissioning and training from Dilo’s after-sales service. Dilo’s
foundation dates back to 1902. In the beginning, the company built interlacing machinery for the
mattress industry. The first needlepunching machines were built in the late 1950s.

NSC nonwoven

NSC nonwoven is another leading supplier of needlepunch technologies. According to company
literature, it offers “an alternative to the nonwovens industry where different economies of scale
can enable opportunities to markets where capacities of scale relative to their investment enable
growth.” The range of technologies includes needlepunched nonwovens and direct web markets, which
includes hydroentanglement, thermal, chemical and laminated nonwovens.

Needle Types And Web Bonding

During mechanical bonding methods, fibers are transported with felting needles and
interlocked in the nonwoven structure. This procedure increases the friction between the fibers,
which reinforces the nonwoven. A very large number of needles are inserted in the needle board of
the needling machine. Germany-based Groz-Beckert KG is a major manufacturer of needles for the
nonwovens industry and supplies two groups of needles – felting and structuring needles. Felting
needles are used to mechanically compact nonwovens. There are different types of needles used with
varying shapes, length distribution and barb characteristics – the most important functional
elements. The correct needle is selected according to the fiber and the required properties and
performances of the end-product.

High-Speed Production

Dilo’s HPCL Hyperlacing needlepunch technology enables the dry consolidation of lightweight
nonwovens between 25 and 80 g/m2 at very high production speeds of more than 100 meters per minute
(m/min), equivalent to 2,000 strokes per minute. A Hyperlace line consists of several Cyclopunch
needle looms. Each Cyclopunch is equipped with four needle boards with approximately 20,000 needles
per meter of working width, and operates with two down-strokes and two up-strokes. Every needle has
just one small barb with a depth of 0.02 millimeters (mm). The needle transports only one fiber per
stroke. The single fiber transport feature provides entanglement of virtually any fiber in the
fibrous batt at high stitching densities. The Cyclopunch needling unit applies completely new
needle beam kinematics that guide the needle on a circular path. Thus, the lightweight web is
actively carried through the needling zone and high-speed production is possible. These machines
permit fine fibers such as polypropylene, polyester and viscose with a fineness of 1.7 to 3.3
decitex to be processed. In comparison to the water-jet process, this is an economical alternative
with ecological benefit and application, for example, in the medical or hygiene sector.

To differentiate the structure of the nonwoven, the web can be further structured using
special machines equipped with structuring fork or crown needles. The surface can be structured as
a velour or rib, or with geometrical or linear patterns.

NSC nonwoven’s Axcess Line

NSC nonwoven recently introduced Axcess, a new range of needlepunch machinery engineered for
medium-capacity markets while maintaining the engineering quality standards of its high-capacity
Excelle nonwoven lines. The technologies include web-forming carding systems, batt-forming
crosslapping with profile capability, batt drafting and felt drafters, needle looms and winding
systems. The engineering of the Axcess range of machinery is based on proven technologies of
Asselin-Thibeau. It is said to offer an alternative for customers who do not require the capacities
available with the Excelle production lines, and also in situations where lower production
capacities and lower capital investment costs are better suited to a company’s corporate
strategies.

It also is designed for alternative bonding technologies in which direct web manufacturing
lines enable the production of different nonwoven fabrics such as spunlace wipes using France-based
Rieter Perfojet’s Avantage technology, or with other bonding technologies such as thermal, chemical
or laminating for composite nonwoven applications.

MD:CD Ratio

If requested, a drafting unit can be integrated in the production line after the first
needling machine. Drafting is one method of achieving a well-balanced tear/strength ratio. Top
priority of every nonwoven producer is to reach an even or isotropic machine direction to cross
direction (MD:CD) of the product. Isotropy refers to a product with the same physical properties in
all directions. The ideal nonwoven has a MD:CD ratio of 1:1. This ratio plays a prominent role in
determining the quality of a nonwoven.

Monitoring

For years, the great challenge for  nonwovens producers was to achieve an isotropic
MD:CD ratio. For this, it is important to produce batts and webs with great uniformity. In the
first stages of production, web formation plays an important part. The fibers should be laid evenly
to form an even fabric weight over the entire width of the web. Today, the big suppliers are
providing instruments to monitor and adjust the MD:CD ratio.

NSC’s Excelle series includes technologies such as the ProDyn® + Qua!sys® web/batt shaping
system to optimize weight uniformity in the finished felt with an optimized uniformity while
reducing fiber costs. The company’s IsoProDyn is said to offer a competitive advantage.

Dilo’s DI-Loom HV needle loom series uses a sophisticated drive concept for an infinitely
adjustable horizontal stroke range from zero up to the maximum installed horizontal stroke of up to
15 mm. The new Elliptical Phase Motion Control (EPMC) Hyperpunch is a kinematic solution that makes
use of the phase adjustment between the horizontal drive shaft and the counter-rotating main shafts
for the vertical stroke of the needle beam, whereby one drive can be saved compared to regular
DI-Loom HV machines. The phase between main shafts and horizontal drive shaft is adjusted by a
mechanical coupling or electrically. This phase adjustment controls the start of the horizontal
needle beam movement relative to the needle dwell phase in the batt. The horizontal needle beam
movement may thus be varied up to about 50 percent of its total, depending on the depth of
penetration and stripper plate gap, which controls dwell time. For many applications, this reduced
range is sufficient. The EPMC kinematics also can be used at high stroke frequencies, while
finish-needling. The EPMC Hyperpunch is an economic solution for pre- and finish-needling.

Dilo’s Hyperpunch elliptical needling was introduced to provide high-quality preneedling and
high-speed finish-needling. The result is low MD draft and low CD shrinkage in the web. This
needling method helps maintain batt regularity because it exhibits low dimensional changes. It
allows high advances per stroke for high throughput speeds.

Products

The list of products made using needlepunch technologies is seemingly endless. Needlepunched
products are applicable in many sectors. Either domestic or industrial textiles can be produced.
Possible application areas are floor coverings, automotive linings, geotextiles, filter media,
synthetic leather or natural fiber felts for upholstery and bedding. Needle felts are an everyday
product and are applied in countless end-uses
(see Table 1).

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Fehrer Products Live On

Fehrer, long known for its high-performance needling solutions, is now operating as Oerlikon
Neumag Austria. The company continues to offer a comprehensive line of needle looms and airlay
equipment.

Oerlikon Neumag Austria, part of the Oerlikon Neumag Carding Division, still operates at the
former Fehrer site in Linz, Austria, which now serves as Carding Division headquarters. The Carding
Division also includes Oerlikon Neumag Italy S.p.A., formerly F.O.R., which provides opening,
blending, and carding machinery; and Germany-based Autefa Nonwovens, which provides crosslappers,
cutters, slitters, and winders.

Linz also is the site of the Carding Competence Center, where three fully operational
nonwoven lines are available for customer trials and research and development work.

Line 1 is a Fehrer Aerodynamic card line with V21/R pre-opener, K12 Random Card, optional
High Loft device, optional needle loom, Thermobond oven and winder. For high-production and special
fiber needs, the RSP volumetric feeder is used. For predominantly man-made fiber blends and
improved web evenness, the CF pneumatic chute feeder may be used.

Line 2 is a needlepunching line complete with pneumatic chute, 2.5m Webmaster 2+2 card,
Autefa 4006 crosslapper with WebMax feature, 5-trio web drafter, two double-board needle looms, web
measuring device and winder.

Line 3 is a pneumatic chute feeding a special triple-doffer Injection card for high-speed
carding applications.

As one of Oerlikon Neumag Austria’s principal product offerings, the needle loom product
range includes single-board looms, double-board looms, tandem looms, quad looms, random velour
looms, and structuring machines. 

Another important component of the Oerlikon Neumag Austria/Fehrer product line is its
papermaker felt needlepunch machinery. Pre-needle and finish-needle machines are offered in widths
up to 15 meters.  Finishing lines can be specified to have multiple needling zones, thus
providing the user a range of flexibility.

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The author wishes to thank the following companies for their support, and for providing
information for this article:

For nonwovens machinery:

• Dilo Group, Germany

• NSC nonwoven (Asselin-Thibeau), France

For needles:

• Groz-Beckert KG, Germany



November/December 2008