Mfg. voluminous fleecy fabrics for use as filter mats, insulation and fire resistant mats

The mfr. of voluminous non-woven fabrics with at least two fleece layers entails joining them together esp. by forming stitches. Distance retaining pieces variable in amount, position and density are inserted between the layers when they are joined. Pref. the distance pieces are hollow bodies which can be placed in a pre-determined pattern or scattered at irregular intervals. The fleeces are nonwoven fabrics with fibres oriented transversely, longitudinally or randomly, are produced mechanically or aerodynamically and can be strengthened mechanically, thermally or chemically particularly on their surface areas.