Jacketing Cables

[jstraley]

I work for a small wire and cable company. We often jacket twisted cables that are a spiral. Several customers want a perfectly round jacket over the spiral configuration. This has been difficult for us to achieve even pressure extruding. Does anybody have any ideas regarding tooling / processing that may help. Jacket materials are usually PVC, Polyurethane or TPE.

[Louis]

Given that thicker sections will shrink more than the thinner sections you will always get some indents. Perhaps a double pass through the crosshead would work to minimize that, but then costs go up.

Is it possible to run the extrusion through a hot drawing die? Again, more costs, but a perfectly round product might demand a premium

[Len]

Can you wrap an isolative paper or foil (thinking co-ax) around the twist, then cover that? Or can you twist a few cotton cord strands along w/ the wire, filling the spirals to create a more even coating surface?

How about an inner foam extrusion layer (cheap and thin/co-extruded or tandem extrusion) to fill the voids, than an isolative layer?

Just suggestions,

Len

[Len]

Given that thicker sections will shrink more than the thinner sections you will always get some indents. Perhaps a double pass through the crosshead would work to minimize that, but then costs go up.

Is it possible to run the extrusion through a hot drawing die? Again, more costs, but a perfectly round product might demand a premium

Additional thoughts...
1.) Maybe a longer land area after the plastic meets the cable strands will smooth out the spiral grooves.
2.) Tandem extrusion has been proposed to lay down an inner layer of foamed PVC, then come back w/ an outer layer of jacket.
3.) We ran a two layer crosshead, laying down an inner and outer jacket to address some troublesome hose applications where the reinforcing cords left spiral grooves in the cover.

Len

[abdelbasit]

some are using internal very low cost filling material befor sheathing , some using two step , the most used is Tandum machine