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Screw elements

Screw elements irrespective of OEM.

The fundamental element of the co-rotating twin screw extruder is the tightly intermeshing conveying elements with an Erdmenger profile. The elements bear closely against each other and the extruder cylinder, creating a stripping effect.

We produce screw elements for your twin screw extruder with diameters of 14 mm to 320 mm. With comprehensive production processes, Extricom enables the element geometries of various extruder manufacturers to be transferred over.

Most importantly for you: any request relating to your specific requirements can be dealt with easily using the relevant OEM designation of the necessary replacement parts.

By screw elements, we mean single or multi-flight feed screws for transportation of the product or melt. Depending on the machine generation, different ratios of outer diameter to axis clearance apply. In the case of low OD/ID ratio extruders, 1 to 3-flight profiles are possible, although current deeper cut models are generally fitted as standard with double-flight elements.

Based on the general basic design principle for self-cleaning screw elements in accordance with "Erdmenger", there are various versions that can affect the technical result.

Essentially, all elements of the co-rotating twin screw extruder are an adaptation or variation of the basic "Erdmenger" geometry. The following basic dimensions can be varied here according to their interdependency:

  • OD/ID ratio
  • Outer diameter and inner diameter matched to the required OD/ID ratio
  • Flight pitch of the screw
  • Length of the element
  • Machine-specific clearances between the element and the barrel hole or the element and the adjacent element.

Every twin screw extruder manufacturer has a specific portfolio of standard elements for material feed for each machine model. Most suppliers offer a modular system comprising 2 to 3 standard pitches, but Extricom delivers virtually any pitch required on request.
Feed segments are often used with a freely cut profile in particular in the feed zone, in contrast to the tightly intermeshing approach, in order to increase feed capacity. This SK element is also often found at downstream feed points with side feeders.

Beispiele:

  1. Standard 2-flight Erdmenger profile, tightly intermeshing
    Fully self-cleaning version but according to the OD/ID ratio of the relevant machine with 100% of the possible free cross-sectional area/feed volume.
  2. SK element with up to approx. 115% free cross-sectional area compared with the tightly intermeshing Erdmenger profile. However, the disadvantage here is the lack of self-cleaning.
  3. SKK twin Schubkante element with up to 131% free cross-sectional area.

The spectrum of feed segments fulfil the process tasks of feeding, conveying, degassing and removal.

Depending on the product and process zone, elements protected in various ways against wear are used. Our highly specialized process engineers have the requisite knowledge to be able to offer optimized solutions.

Replacement parts including those made from special steels produced in a powder metallurgy process are also in our scope of supply and represent the majority of our yearly production. A small extract from our comprehensive materials catalogue can be found in the "Materials" section.

In addition to the listed elements, other versions are available, and can be matched to your particular application. We are expanding our portfolio to include a number of new versions as a specialized solution for technical process-related tasks such as:

  • Optimization of the feed behaviour during the addition of products.
  • Pressure build-up capacity.
  • Minimization of pulsations of the melt throughput.