Sudarshan Telecom: PIJF Copper Telephone Cables

WIRE DRAWING (RBD):
8 mm dia Copper Rod is drawn into 2.5 mm dia copper rod by this process. The output 2.5 mm dia copper rod is taken in baskets called formers as input to the next stage.

TANDEM INSULATION (TANDEM LINE) :
In this process the 2.5 mm dia copper rod is further drawn into the required size of 0-4 nun, 0.5 mm or 0.63 mm dia wire by the wire drawing machine. It is annealed in-line and then extruded with MDPE/HDPE in the Tandem Extruder line. The entire operation, is done continuously in one stage and insulated wire of various colours (total 9 colours) are taken in plastic bobbins.

TWINNING OR GROUP TWINNING :
The insulated bobbins are then made into pairs of matching colours and proper lay lengths in individual twinning machine or are paired and bunched into units of 10 or 20 pairs in one stage by group twinning machine.

STRANDING (DRUM TWISTER) :
The individual pairs or the groups of 10 or 20 pair-units are bunched together in this stage into 50 or 100 pair cables in one stage. And for higher size cables they are further layed up, into 200, 400 or higher pair cables in 2nd state of operation in the same machine. The stranded unit of 20/10 pairs are identified by color binders and overall binders for super units of 50/100 pairs. The core is also filled with Jelly in this process. After filling, one layer of polyester tape is applied longitudinally over the core and finally one nylon thread binder is applied helically over the polyester tape. The stranded core is taken in 1600 or 2200 mm dia steel drum for next process.

SHEATHING :
Here, the core is first flooded with a layer of jelly and then one tape of poly-al (polythene coated aluminium tape) is applied longitudinally before the core is sheathed in the extruder with black LDPE.

ARMOURING :
Two layers of black LDPE/HDPE tape (called bedding tape) are applied helically over the Sheath cable and then two steel tapes also applied helically over the bedding tape in this operation.

JACKETING :
The armored cable is finally jacketed in this process by applying a layer of black LDPE/HDPE, which is extruded on the armored cable. Finally, marking is done on the jacket surface for sequential length and other details on each one-meter length of the cable.

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