Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Filter cartridges may have a core element formed of a non-filtering, self-supporting non-woven mass of indefinite length continuous synthetic polymeric core fibers, and at least one annular filtration zone layer formed of a mass of non-woven indefinite length continuous synthetic polymeric filtration fibers. The non-woven core element is most preferably formed in situ during filter cartridge manufacturing by melt-blowing synthetic polymeric core fiber streams toward a forming mandrel. The non-woven core element is completely solidified prior to the filtration zone fibers being melt-blown thereon so that the core and filtration fibers are predominantly mechanically interlocked with one another, instead of being melt-bonded thereto. Filter cartridges of predetermined length may be cut from an upstream filter cartridge preform of indefinite length by subjecting the preform to forced cooling air to thereby minimize (if not eliminate entirely) significant filter cartridge shrinkage over time.

Abstract: Apparatus and methods are disclosed whereby elongate preformed thermoplastic elements are friction-welded coaxially in an end-to-end manner so that the core elements are joined integrally to one another. Most preferably, the elongate elements are perforated tubular elements formed of a thermoplastic material which are employed as core elements in the production of cylindrical melt-blown filter cartridges. As such, the integrally joined core elements can be rotated and traversed as a unit relative to a melt-blowing die during the continuous production of indefinite length cylindrical melt-blown filter cartridges.

Abstract: Apparatus and methods are disclosed whereby elongate preformed thermoplastic elements are friction-welded coaxially in an end-to-end manner so that the core elements are joined integrally to one another. Most preferably, the elongate elements are perforated tubular elements formed of a thermoplastic material which are employed as core elements in the production of cylindrical melt-blown filter cartridges. As such, the integrally joined core elements can be rotated and traversed as a unit relative to a melt-blowing die during the continuous production of indefinite length cylindrical melt-blown filter cartridges.

Abstract: Apparatus and methods are disclosed whereby elongate preformed thermoplastic elements are friction-welded coaxially in an end-to-end manner so that the core elements are joined integrally to one another. Most preferably, the elongate elements are perforated tubular elements formed of a thermoplastic material which are employed as core elements in the production of cylindrical melt-blown filter cartridges. As such, the integrally joined core elements can be rotated and traversed as a unit relative to a melt-blowing die during the continuous production of indefinite length cylindrical melt-blown filter cartridges.

Abstract: Apparatus and methods are disclosed whereby elongate preformed thermoplastic elements are friction-welded coaxially in an end-to-end manner so that the core elements are joined integrally to one another. Most preferably, the elongate elements are perforated tubular elements formed of a thermoplastic material which are employed as core elements in the production of cylindrical melt-blown filter cartridges. As such, the integrally joined core elements can be rotated and traversed as a unit relative to a melt-blowing die during the continuous production of indefinite length cylindrical melt-blown filter cartridges.

Abstract: Apparatus and methods are disclosed whereby elongate preformed thermoplastic elements are friction-welded coaxially in an end-to-end manner so that the core elements are joined integrally to one another. Most preferably, the elongate elements are perforated tubular elements formed of a thermoplastic material which are employed as core elements in the production of cylindrical melt-blown filter cartridges. As such, the integrally joined core elements can be rotated and traversed as a unit relative to a melt-blowing die during the continuous production of indefinite length cylindrical melt-blown filter cartridges.