Rounded Barb Styles
Undeniably, the barbs are the most important single element of the felting needle. It is the barb or barbs on the blade of the felting needle that carry and interlock fibers during the stroke of the needle and penetration of the fiber web. Therefore, it is easy to understand the relationship that barb design and shape can have on fiber damage and on nonwoven physical properties.
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Figure 3: Rounded barb needle
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Several needle manufacturers now produce what are called rounded barb styles. This barb style can be seen in Figure 3. All edges are rounded and the barb face is formed so that only rounded smooth edges engage fiber. This minimizes any fiber damage caused by the barb itself.
In contrast to the rounded barb styles is the conventional or cut barb. Illustrated in Figure 4, the cut barb has been in use since the first felting needles were produced.
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Figure 4: Conventional cut barb needle
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It is made with a chisel-like tool that cuts into the blade’s edge. All surfaces of the cut barb are flat and all edges are sharp. As fibers are engaged, they must lie across two sharp edges and one flat surface. The conventional cut barbs can be effective but not without causing fiber damage higher than necessary. The cut barb represents a compromise between the barb’s fiber carrying capacity and the barb’s fiber destruction characteristics. The higher the fiber carrying capacity, the higher the fiber destruction. With the use of conventional cut barbs this relationship is unavoidable.
Applications where the rounded barbs are most advantageous are those where fabric strength is extremely important and those where either the fiber is very delicate or where excessive fiber damage is especially detrimental to the useful life of the fabrics.
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