Clextral Extruder Parts: Screw Elements for BC and EVOLUM Twin-Screw Extruders

EXTRUTEX manufactures replacement screw elements, kneading blocks, screw shafts, barrel sections and wear liners for Clextral BC and EVOLUM twin-screw extruders. Our replacement components are designed for food and feed processing applications, including high-moisture cooking, textured protein, expanded snacks and breakfast cereal production.

We manufacture replacement parts using original technical drawings or measured reference samples. Each component is produced against the confirmed dimensions and geometry of the specific machine configuration. Dimensional verification is carried out before shipment to help ensure correct fitting and reliable operation.

Technical Specifications

Clextral BC and EVOLUM: Two Different Screw Platforms

One of the most important steps when ordering replacement screw elements is identifying the correct Clextral machine generation. BC and EVOLUM are different platforms, and their screw configurations, shaft interfaces and component geometries must be checked independently.

A screw element designed for a BC machine will not necessarily fit an EVOLUM shaft. The reverse is also true. Similar external dimensions do not prove that two components are interchangeable. Differences in spline or keyway configuration, centre distance, element length, pitch and flight geometry can prevent correct installation or affect the extrusion process.

Why we request the machine nameplate first

The machine nameplate provides the initial identification needed to establish the correct platform and machine size. Once the generation and configuration are confirmed, the technical drawing or reference sample can be assessed for manufacturing.

• Identify whether the machine belongs to the BC or EVOLUM generation.
• Confirm the machine size and available configuration information.
• Check the shaft interface and screw arrangement.
• Verify the dimensions and geometry of the requested element positions.
• Confirm the replacement design before machining begins.

Replacement Screw Elements for Food and Feed Extrusion

Clextral twin-screw extruders are used in demanding food and feed processes. Depending on the product and recipe, the screw configuration must provide conveying, mixing, cooking, pressure development and controlled material flow through the barrel and die.

Replacement elements must reproduce the required geometry and maintain the intended screw configuration. A small dimensional difference can affect the relationship between adjacent elements, the available clearance and the material's movement through the processing zones.

Conveying screw elements

Conveying elements move material along the screw and contribute to filling, residence time and pressure development. Their geometry, pitch and position influence the conveying capacity of each section.

EXTRUTEX manufactures replacement conveying elements according to the confirmed shaft interface, outer diameter, pitch and required element length. Individual worn positions can be replaced without automatically ordering a complete screw set.

Kneading blocks

Kneading blocks are used in mixing and cooking sections where the material experiences mechanical work and controlled shear. Their stagger angle and configuration influence material movement, mixing intensity and the overall processing profile.

We manufacture single-piece and assembled kneading block configurations according to the supplied drawing or measured sample. The replacement must match the original geometry and intended position in the screw arrangement.

Screw shafts and shaft assemblies

The screw shaft provides the mechanical connection between the drive system and the screw elements. The spline or keyway, shaft dimensions and element positioning must be checked carefully.

EXTRUTEX can manufacture replacement screw shafts and shaft assemblies according to confirmed drawings and reference measurements. Shaft material and heat treatment are selected according to mechanical requirements and the machine configuration.

Barrel sections and wear liners

Barrel sections and internal wear liners provide the working surface surrounding the screw elements. Their condition affects operating clearances, material flow and the consistency of the extrusion process.

We manufacture replacement barrel sections and liners with specified internal dimensions and surface requirements. Available liner and surface-treatment options depend on the application, material compatibility and the required service conditions.

Where Clextral Screw Elements Wear During Cooking

High-moisture cooking applications place different demands on screw elements and barrel surfaces compared with many conventional polymer compounding processes. Product composition, moisture level, temperature, screw speed, pressure and residence time all influence wear.

Cook-zone kneading blocks

Kneading blocks in the cooking section experience mechanical loading and material shear. Whole grains, fibres and mineral-containing ingredients can increase abrasive wear. Over time, flight crests and working surfaces may become rounded, changing the original geometry.

Changes in the kneading block profile can influence the mechanical work applied to the product. This may contribute to variations in texture, cooking behaviour and product consistency.

Final conveying section before the die

The final conveying elements operate in the pressure-building section ahead of the die. In processes where back-pressure is maintained at a high level, this section can experience demanding operating conditions.

Wear in this area can affect pressure development and material delivery. A change in product expansion, density or consistency may indicate that the screw configuration should be inspected.

Barrel bore wear

Whole-grain ingredients, fibres and abrasive recipe components can wear both the screw elements and the barrel bore. Replacing screw elements without assessing the surrounding barrel condition may leave excessive operating clearance in place.

For this reason, EXTRUTEX recommends checking the condition of the barrel and liners when replacing heavily worn screw components.

Process Changes Can Reveal Wear Before Component Failure

Wear does not always begin with a broken screw element or a visible mechanical problem. In food extrusion, changes in product characteristics can provide an early indication that the screw geometry or operating clearance has changed.

Operators may notice:

• Changes in product colour at unchanged operating settings.
• Variations in texture or product structure.
• Changes in expansion or finished product density.
• Unstable pressure or material flow through the die.
• Changes in process consistency between production runs.
• Increasing energy demand or altered operating behaviour.

These symptoms are not proof of screw wear by themselves. Recipe changes, raw material variation, moisture, temperature, die conditions and machine settings can also affect the finished product. A dimensional inspection helps establish whether component wear is contributing to the problem.

EXTRUTEX Replacement Parts for Clextral BC and EVOLUM

Individual Replacement Elements or Complete Screw Sets

Not every maintenance project requires a complete replacement screw set. If inspection confirms that wear is concentrated in a particular section, EXTRUTEX can quote the affected positions individually.

For example, if the main wear is found in the cooking zone, replacing the affected kneading blocks may be more practical than replacing every conveying and mixing element along the shaft.

A complete matched set may be appropriate when wear is distributed across several processing zones, when the original screw configuration needs to be reconstructed, or when the customer wants a coordinated replacement for planned maintenance.

• Individual elements: Suitable for localised wear and targeted maintenance.
• Matched screw section: Suitable when several adjacent positions require replacement.
• Complete screw set: Suitable for extensive wear or a planned full screw replacement.

The recommended scope depends on the measured condition of the existing components, the required operating clearances and the customer's maintenance plan.

Material Selection for Food and Feed Extruder Parts

Material selection must reflect the actual process duty. Food-contact components require suitable material documentation and surface conditions, while abrasive recipes may require a different combination of corrosion resistance and wear resistance.

Material selection for abrasive recipes

Whole grains, high-fibre ingredients, mineral premixes and bone-meal-containing formulations can increase abrasive wear. Aquafeed applications may also involve demanding combinations of moisture, pressure and recipe ingredients.

For these conditions, EXTRUTEX evaluates the required corrosion resistance, hardness, wear resistance and processing environment before confirming a material specification.

Dimensional Interchangeability and OEM Reference Verification

Replacement screw elements must reproduce the critical dimensions of the original component. EXTRUTEX uses original technical drawings where available and measured reference samples when drawings are unavailable.

The purpose is to manufacture a replacement that matches the confirmed machine configuration and can operate in the intended position alongside existing components where compatibility has been verified.

Dimensions and features checked

• Spline and keyway configuration.
• Screw element outer diameter.
• Element pitch and conveying geometry.
• Element length and axial dimensions.
• Stagger angles for kneading blocks.
• Centre distance and screw arrangement.
• Relevant clearances and mating dimensions.
• Position and orientation within the screw assembly.

Mixing replacement elements with original components on the same shaft is possible when the relevant dimensions and geometry have been confirmed. It should not be assumed from the machine brand or apparent external similarity alone.

Manufacturing Without Original Drawings

Older machines and long-running production lines may no longer have complete technical documentation available. In these cases, EXTRUTEX can assess a worn component and reconstruct its geometry using dimensional measurements and available reference information.

The process begins with identifying the machine generation and component position. We then inspect the reference part, determine which surfaces remain suitable for measurement and establish the original geometry as accurately as the available evidence allows.

Sample-based manufacturing process

1. Machine identification: Confirm BC or EVOLUM using the machine nameplate.
2. Component identification: Establish the screw position and component type.
3. Reference measurement: Measure the worn part and identify unworn reference surfaces.
4. Geometry reconstruction: Use available drawings, sample measurements and assembly information.
5. Technical confirmation: Confirm material, dimensions and manufacturing requirements.
6. Production: Manufacture the replacement component to the approved specification.
7. Inspection: Verify critical dimensions before packing.

If a component is severely worn, a single sample may not contain enough information to reconstruct every original feature. In that situation, a section drawing, another reference element, an unworn component from a different position or a sister-machine reference can help establish the original geometry.

Quality Control and Inspection Documentation

Dimensional accuracy is essential for screw elements, kneading blocks and barrel components. Each batch is subject to dimensional inspection, with additional documentation available according to the order requirements.

Lead Time and Order Quantity

The minimum order quantity is one piece. Customers can order individual screw elements, selected kneading blocks, barrel components or a complete matched screw set.

For replacement parts used on imported machines, the typical manufacturing lead time is 30–45 days after the required material is available and the technical drawings or reference geometry have been confirmed. Transit time is additional.

Special stainless steel grades, non-standard surface finishes and materials that are not held in stock may extend the manufacturing schedule. The final lead time is confirmed after reviewing the technical requirements.

Information Required for a Quotation

To reduce the time required for technical assessment, please provide the following information with your enquiry:

• Machine nameplate photograph: This is the first step in confirming BC or EVOLUM and the machine size.
• Component position: Identify the worn element's position on the screw shaft, if known.
• Whole screw photograph: A photograph of the complete screw assembly helps establish the component arrangement.
• Worn component photograph: Include a ruler or measuring reference beside the part.
• OEM part number: Provide the original part number if it is legible and available.
• Technical drawing: Supply the original drawing if available.
• Material requirements: Specify product-contact requirements, recipe conditions and any required material documentation.

After reviewing the information, EXTRUTEX confirms the platform and component requirements before issuing a quotation. Production begins after the technical specification has been agreed.

Why Choose EXTRUTEX for Clextral Replacement Parts?

• BC and EVOLUM platform identification: We treat the two machine generations separately and check the configuration before production.
• Drawing-based manufacturing: Replacement components can be produced using confirmed technical drawings.
• Sample-based reverse engineering: We can assess worn parts when original drawings are unavailable.
• Food and feed application experience: Material and component requirements are considered in relation to the processing duty.
• Flexible order quantities: Individual replacement components can be ordered from one piece.
• Dimensional inspection: CMM inspection and supporting documentation are available according to the order specification.
• Component-level replacement: Customers can replace selected worn positions instead of automatically purchasing a complete screw set.

EXTRUTEX combines Austrian design, laboratory and R&D capabilities with manufacturing in China. Our focus is on supplying technically verified replacement components for industrial extrusion and compounding equipment.

Frequently Asked Questions

Clextral is referenced solely to identify the equipment platform for which replacement components may be manufactured. EXTRUTEX is an independent replacement-parts manufacturer and is not affiliated with, authorised by or endorsed by Clextral. Compatibility is subject to machine identification and dimensional verification.