Core Proficiencies

• Overview
• Window and door profile extrusion
• Coextrusion
• Tool construction
• Dry-blend composition
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Building blocks of our success

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• Leadership guidelines
• Core proficiencies
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GEALAN international:

Success factors

The building blocks of our success

Core Proficiencies of the GEALAN Group

Extrusion of Window and Door Profiles From PVC

"Producing quality always requires a perfect interaction between man and technology. GEALAN uses modern high-tech production to shape plastic with precision."

Roland Jahn, Executive Director of Technology

 

 

 

 

The word "extrusion" means the the continual pressing of strands of malleable material or its preliminary product (i.e. granules). An originally solid extrusion mass is transformed into a homogeneous flux through heating, compression and shearing; in other words, the extrusion mass is plastified.

Before the extrusion process can begin, the raw materials are delivered by truck. After the received goods are inspected, the main components (PVC, chalk and titanium dioxide) are mixed according to GEALAN's special recipe, together with certain additives. In two separately controlled mixing lines, the ingredients are all automatically measured, enriched with circulation material, transported, dosed, mixed, dried and cooled. The final mixture is then stored in silos to await the actual extrusion.

The dry blend then leaves the silos through an extrusion funnel into both cylinders of the double-screw extruder. The two counterrotating screws transport the dry blend into the tool die.

The extrusion mass is warmed by heating elements on the cylinder walls and by the friction of the mass, so that the PVC melts into semifliud plastic paste. The cylinder temperature is controlled by arranging the heating elements into zones, allowing for a constant, controlled warming. The molten PVC is then pumped into the tool form, creating the geomety of the end profile.

There, the following steps take place:

• transport of the dry blend
• compression of the extrusion mass into a compact solid
• the extrusion mass is melted into flux
• the flux is homogenised
• the flux is then pressed through the tool die

The extrusion line contains–apart from the extruder and the tool die–followup equipment to calibrate, cool, strip, cut and deposit the extruded profile.

All followup machines need to be coordinated with its extruder's delivery rate. The profile is hot and unstable when it leaves the tool die, and must be cooled in the calibrator, where it receives its final form. A vacuum is created within the calibrator, sucking the outer surface if the profile onto the walls of the calibrator. After passing through water-filled cooling baths and the stripper, the profiles are covered with protective foil on the inner and outer sides, before it is cut into six metre long pieces by the seperator saw. Afterwards, the profiles are automatically stacked into a waiting container. After they are packed, the profiles are either stored in the logistics centre or directly loaded into waiting trucks and delivered straight to the cunstomer.

GEALAN extruded its first window profile in 1968. Since then, the extrusion process had been constantly improved upon and further developed, as seen by such developments as the coextruded window profiles.