Groz-Beckert felting needles for filter media 

03.08.2011


Albstadt: What links humanity with a healthy environment more than clean air and pure water? Efforts are being undertaken worldwide by governments and industry to reduce harmful emissions.


The astonishingly rapid growth of filter media is proceeding hand in hand with this development. According to estimates, filtration will reach a market volume of between 75 and 100 billion USD by the year 2020. Even today, nonwovens filter media have an international market share of 27 percent. With their variety and their diverse properties, they promise enormous potential for the future. Make the most of it with the ideal felting needle for every application – from Groz-Beckert.

Selection and characteristics of felting needles

For optimum needling results, precise adjustment of the barb geometry to the fiber is extremely important. The thicker the fiber, the deeper the barb has to be.

Correct selection of the felting needle plays a decisive role here. Where preventing damage to the fibers is a key issue, the needles chosen should have features such as small barbs and a three-dimensional rounded shape (Groz-Beckert standard). When working with high-strength fibers, felting needles with a reduced number of barbs and a reinforced working part cross-section are used.

Tolerances in the 1/1000th mm range and absolutely even production ensure ultra-precise barb measurements - from one needle delivery to the next. This provides the absolute assurance of process reliability and reproduction accuracy for our customers, and consequently a consistently high standard of filter manufacturing quality.


Felting needles for special applications

Special coatings for long service life

As certain fibers such as glass fibers are highly abrasive, in this case the service life of the felting needle is of
central importance. Here, needles are used which have been given a special coating such as partial chrome
plating or GEBEDUR® (refer to technical info sheet "GEBEDUR® needles".

Increase in tear strength and stability due to support fabric

To increase the tear strength and improve dimensional stability, backing materials known as support fabrics are
often worked into the filtration medium (needled from both sides). Barbs with a minimal or even negative kick-up
are designed to ensure the most careful possible treatment of the support fabric.

Teardrop-shaped needle to protect the support fabric

A special working part cross-section is also ideal for taking optimum care of the support fabric.
The tear drop-shaped needle has only one edge with barbs and can be placed in a certain location relative to the
direction of movement in line with specific type of gentle treatment required (see technical information sheet
"The teardrop-shaped working part".

Diversity among filter media

In ultra-fine filters, the finished filtration medium on the intake side is made of ultrafine or microfiber layers with a fineness of < 1 dtex. Here, needles should ideally be selected which have barb sizes of ≤ 0.04 mm.

Because of the high degree of chemical resistance and mechanical strength required, a large number of in some cases highly costly technical fibers are used to manufacture needled filter media, such as aramid, glass fiber, P 84, etc.

Different treatment finishes used for filter media


In order to guarantee that particle deposits are formed on the surface of the filter, which exert a positive effect on the actual filtration (e. g. surface filtration), after needling usually a „smoothing“ process is carried out by means  of calendering, the application of an ultra-fine fiber layer, or by coating with a material such as PTFE.

The benefits of needled felts:

  • Cost-efficient manufacture
  • High fiber retention rates
  • Suitable for deformable and non-deformable gel-like particles
  • Defined determination of pore sizes through targeted selection of needle fineness and barb size
  • High elasticity compared to other textile constructs
  • High flexibility in respect of width, thickness, volume, etc.
  • High air permeability, large fiber surface
  • Can be combined with other textile or non-textile surfaces

The availability of a wide choice of suitable needles which vary in terms of their barb size, barb shape, working part fineness and working part cross-section allows Groz-Beckert to offer the ideal felting needle for all needled filter media. Improved wear properties due to special coatings ensure a consistent needling result during the manufacturing process. This helps our customers to manufacture with the utmost reproduction accuracy and process reliability and so assume and maintain a leading position in the marketplace.



Contact:

Birte Kleefisch
Corporate Communications 

Phone +49 7431 10-2277
E-Mail: birte.kleefisch@groz-beckert.com