Canadian Plastics

Pipe Market Report: Throughput and flexibility sell extrusion lines

Canadian Plastics   



Krauss-Maffei has booked orders for almost 50 of its newest generation of 36 L/D counter-rotating, twin-screw extruders since showing them at K 2001. In the fiercely competitive Italian market, where ...

Krauss-Maffei has booked orders for almost 50 of its newest generation of 36 L/D counter-rotating, twin-screw extruders since showing them at K 2001. In the fiercely competitive Italian market, where margins are relatively small, the benefits of the new extruder have proven compelling. Pipe manufacturer Sirea Srl took delivery of a KMD 114-36D extruder in May 2002. Sirea is one of Italy’s leading producers of PE and PVC pipe and pipe fittings.

For Tullio Bosi, Sirea’s president, the deciding factor in the purchase decision was the dramatic increase in throughput that can be achieved without pulsation.

The 36 L/D extruders are not simply longer versions of a 26 L/D machine. The new machines have two venting zones, instead of the usual one. At 15D along the barrel, gases are allowed to escape through two long atmospheric venting slits in the barrel. After further compression and heating the material reaches a second venting zone, where a vacuum system extracts the remaining volatile components. Removing air (and its insulating properties) at an early stage of the process significantly increases heat transfer within the material.

As a result, although the new machines have 17% higher throughput than 26 L/D machines, compression values at the throttle are lower and there is significantly less wear on the screw and barrel, so the machines have longer service life.

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There was also news earlier this year that Madepla S.A. is entering the Mexican pipe market, producing PVC pipe up to 315 mm (12 in.) in diameter on two high output extrusion lines from American Maplan Corp. Madepla will install the two lines in a facility it is developing about 75 km northeast of Mexico City.

The lines are characterized by exceptionally high versatility for various pipe diameters and the ability to make fast product changeovers with minimal effort. The smaller line can produce diameters from 50 mm to 125 mm, while the larger system can range from 150 mm to 450 mm. Rated maximum throughput is 720 kg/hr for the larger system, and 460 kg/hr for the smaller.

The downstream section of the larger line is a recent design that simultaneously maximizes pipe quality, handling and output speed of medium to large diameter pipe.

Madepla has experience compounding and injection molding PVC, but these two lines are the company’s first extrusion systems.

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