Cable and pipe coding: a mark that survives the line, the drum and the ground

Most of what goes onto a jacket is identification: type and size, voltage or pressure class, the standard the product is made to, the maker, and a batch or date code. Those items behave much the way they do on any other product, and the date and batch side of it is covered on its own page.

The length mark is the item that changes the problem. A metre mark is not a fixed string, it counts: it has to increment with the product, stay in step with the haul-off at running speed, and pick up again in the right place after a line stop. That is an encoder and controller question before it is an ink question, and it is why a cable enquiry looks different from a carton enquiry.

Pipe usually carries simpler content and harder conditions. The mark is often the material, the diameter and pressure class, the standard reference and the production date, repeated at intervals along the extruded length rather than printed continuously. What it then has to survive is a life outdoors or underground, which is a different test from a shelf life.

A solvent system is the usual starting point, because nothing soaks into a PVC jacket or a PE pipe wall: the carrier has to flash off. On a fast line that is the whole problem, and the drying budget is arithmetic — the distance from the printhead to the first capstan, water trough or coiler, divided by the line speed.

Two points about line layout matter more than anything on an ink datasheet. Where the head sits relative to the cooling trough: a product printed warm dries faster but its dimensions are still moving, while a cold, dimensionally stable surface is harder to wet. And whether the product passes a water trough or a spark tester after the head: a wet surface and a wet print are not the same thing, and the print has to be dry before it gets there.

For this case we supply a 42 ml cartridge in the HP45 format, in 12.7 mm and 25.4 mm print widths, and we formulate the ink ourselves. Print width is what decides how much content fits in a single pass. Stacking heads extends the height, at the cost of one more alignment to hold and one more place for a dropout to appear.

On a continuous extrusion run this is usually not a choice. Nobody stops an extrusion line to mark the product by hand, so the head is mounted on the line, takes its trigger from an encoder or a proximity switch, and prints while the product moves. What is achievable in one pass depends on the print height, the number of lines and the ink, and it is bounded by how much time the surface gives the drop to dry — which is why we ask for the line speed and the print height rather than quoting a figure in advance.

A handheld unit still has a place further down the process: re-marking a cut length, marking the end of a coil, coding drums and pallets, or short runs where setting up a station on the line is not worth the effort. On a curved, glossy jacket its weak point is consistency, because position and angle vary with the hand holding it.

To be clear about what we supply: we make the cartridge and we formulate the ink. The handheld and in-line printers are supplied together with specialist equipment-manufacturing partners — we qualify and support the combination, so that cartridge, ink and machine settings work as one system, but the machine itself is not built in our plant.