Beneﬁcial to many applications, the hot air welding technique is used
instead of the traditional sewn seams. Increased efﬁciency is one of
the major beneﬁts – no needle holes equals increased ﬁltration, an
important factor when choosing a ﬁlter for your use.
The manufacturing process in hot welding is fairly simple. The two
edges of the felt are heated and pressed together, forming what looks
like an over lapped seam. Special continually-operating machines,
resembling sewing machines, press the felt together and advance it
to the hot air nozzle. Heat is applied to the seam edges to their
softening/melting point without heating the rest of the felt creating a
uniform seam with no interruptions or stoppages.
Although welded seams are not feasible for all ﬁlter applications, the
beneﬁts over traditional sewn seams are clear.