Double-Strand Core Extrusion Reduces Costs

In extruding plastics profiles, double-strand extrusion produces two profiles simultaneously, reducing the capital investment and the required floor space for the extrusion line.


In profile manufacture, coextrusion can cut costs substantially, said KraussMaffei.

For example, producing a profile with a regrind core covered with virgin material in all visible areas sharply reduces material costs.

Schuco International has recently invested in a profile system using core extrusion technology.

Schuco International is a global player, developing and marketing complete systems using plastics, aluminium and steel.

One current project combines double-strand extrusion with core technology.

Double-strand extrusion produces two profiles simultaneously.

This reduces both the capital investment and the required floorspace for the extrusion line.

Schuco embarked on a cooperative project with Greiner Extrusion and KraussMaffei Berstorff to develop a double-strand extrusion system for producing its five-chamber main window profiles.

The big challenges were to design the die, to split up and manage the melt streams, and develop a cost-effective extruder concept.

The combined know-how of the three partners made it possible to meet these challenges in a remarkably short time.

* Pressure-optimized channel system - the material ratios in Schuco's main window profiles are around 60% virgin PVC and 40% regrind.

The new system uses two extruders, both of which supply both strands.

The melt streams are split via a pressure-optimized channel system so that they reach the dies in the required pattern.

The two extruders need to be positioned very close together in order to feed the channel system effectively.

The concept uses two separate KMD 90-36/P profile extruders from KraussMaffei Berstorff, each on its own base frame.

The main control cabinets are positioned at a distance from the extrusion line.

Two extra compact control units, positioned close to the extruder output zone, house the die control circuits and the operator panels.

Both operator panels (one for each extruder) are on the operator side.

Each extruder can be operated separately, or the two extruders can be operated in synchrony.

This gives Schuco maximum flexibility to respond to future requirements.

* About KraussMaffei - KraussMaffei is the only supplier worldwide of the three key machine technologies for the plastics and rubber compounding and processing industries.

The KraussMaffei brand stands for comprehensive solutions for injection and reaction moulding, while the KraussMaffei Berstorff brand covers the whole spectrum of extrusion systems, including complete extrusion lines.

KraussMaffei has a unique wealth of know-how across the whole range of processing methods.

As a technology partner, it links this know-how with innovative engineering to deliver application-specific and integrated solutions.

KraussMaffei operates a network of 70 subsidiaries and sales agencies close to customers worldwide.

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