Process for manufacturing a woven slide-fastener unit

A loom for producing a slide-fastener stringer having a pair of interconnected stringer halves each with a respective support tape and a coupling element having a multiplicity of coupling heads along an edge of the tape, said loom comprising:

• (a) means for advancing a warp consisting of a pair of groups of warp threads;
• (b) a forming mandrel disposed between said groups of warp threads;
• (c) means for raising and lowering said mandrel;
• (d) harness means for shedding each of said groups of warp threads on opposite sides of said mandrel to form a pair of warp sheds at the same level;
• (e) a pair of weft needles swingable into said sheds from opposite sides of the warp for inserting into said sheds respective strands of synthetic-resin monofilament adapted to form said coupling elements and looping said strands around said mandrel while withdrawing said strands at the sides of the warp from which they were inserted after crossing them over, thereby laying each strand as a double weft in each of said sheds;
• (f) means for beating up the weft so that each coupling head is formed as a loop around said mandrel and has a pair of shanks inlaid in the respective tapes as a double weft, said mandrel being raised and lowered in the cadence of movement of said needles into and out of said sheds;
• and
• (g) a vertical displaceable mandrel holder and magnet means for releasably retaining said mandrel holder in upper and lower positions.