Pipe extrusion: Internal cooling system boosts productivity

Plastics pipe extruders are offered a new tool to help increase their lines' efficiency when processing polyolefins. Developed and manufactured by KraussMaffei Berstorff, this new internal pipe cooling (IPC) system is said to dramatically reduce the initial cost and space requirements for a new pipe extrusion line, while also helping increase the productivity of already-installed pipe extrusion lines.

KraussMaffei Berstorff is the extruder manufacturing business unit of plastics processing machine maker KraussMaffei (Munich, Germany). The IPC system sucks ambient air through the center of the pipe at high speed, counter to the haul-off direction, by means of a side channel compressor. IPC, used in addition to conventional external water cooling in vacuum tanks and cooling baths, cools the moving pipe gently from the inside.

According to KraussMaffei Berstorff, the new technology can cut the required length of the cooling zone by as much as 40%. This means producers save floorspace without losing production speed. The total purchase cost of the extrusion line is also significantly reduced. Alternatively, keeping the cooling zone the same length and adding an IPC system can increase the productivity by up to 60% compared with a conventional production line, says the company.

The gains can be especially impressive for processors who make thick-walled pipe, which of course is more difficult to cool than pipe with thin walls. The IPC system can be used with all polyolefin pipe extrusion lines extruding pipe sized from 110-2500 mm in diameter producing SDR 26 pipe and all thick-walled pipes. SDR is a pipe's Standard Dimension Ratio (also known as Dimension Ratio) and describes the minimum wall thickness of pipe and fittings. SDR is equal to the average outer diameter divided by the minimum wall thickness. The lower the SDR, the thicker the wall and thus the stronger the fitting.

Continuous active control of the air suction volume on the IPC adjusts for ambient conditions to ensure uniform cooling even when the temperature in the processing plant changes. The IPC system also helps processors save on energy use, claims KraussMaffei. "Because the system operates only with ambient air, it can save energy. No special cooling media are required. An additional advantage is that productivity can be increased without using much more cooling water than before," explains Daniel Lachhammer, product manager for pipe extrusion at KraussMaffei Berstorff.