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

BC and EVOLUM are different screws

BC and EVOLUM are different generations of machine, and the difference is not cosmetic. Treating them as one platform is the most common reason a first enquiry goes wrong: an element quoted for a BC will not necessarily fit an EVOLUM shaft, and the reverse is equally true.

So the first thing we ask for is the machine nameplate, not the drawing. Once the generation is confirmed the drawing tells us the geometry; before that it tells us nothing useful.

Where Clextral elements wear

These machines are often run on high-moisture cooking duty — textured protein, expanded snacks, breakfast cereal — where the barrel is long and the product spends time at temperature. That duty moves wear away from the places a compounding operator would look first.

• The cook-zone kneading blocks take the shear, and their flight crests round off before the conveying elements show measurable loss
• The final conveying section ahead of the die wears on pressure duty, particularly on textured protein where back-pressure is held high
• Whole-grain and fibre-heavy recipes are abrasive in a way fine flour is not, and they attack the bore as well as the element

Because the cook profile depends on geometry, the first symptom is usually product rather than hardware: colour, texture or degree of expansion drifting at unchanged settings. That is easier to see than a clearance measurement, and it is the reason lines run past the point where the parts should have been changed.

What we make for BC and EVOLUM

• Conveying screw elements and screw segments
• Kneading blocks, single-piece and assembled
• Screw shafts and shaft assemblies
• Barrel sections, wear liners and liner replacement

Individual positions or a matched set. Where only the cook zone is worn we quote those positions rather than a full screw — a full set is not automatically the cheaper answer, and it is never the faster one.

What interchangeable actually means

Interchangeable means the element fits the shaft, matches the centre distance and reproduces the conveying geometry, so it can run alongside original parts on the same shaft. We work from OEM drawings where they are available and from measured samples where they are not.

• Same spline and keyway
• Same outer diameter and pitch
• Same stagger angles
• Can be mixed with OEM parts on one shaft

Materials for food-contact parts

The grade follows the duty, not the brand. A textured-protein line and a dry snack line on the same platform will not take the same steel.

Material selection

Product contact, general food duty	300-series stainless, nitrided or through-hardened
Product contact, abrasive recipe	Corrosion-resistant grade at 58–62 HRC (mineral premix, bone meal, aquafeed)
Non-contact positions	Nitrided steel or tool steel as for compounding
Barrel bore	Polished or plated bore; nitrided, alpha-101, HIP PM or laser-clad liner

Verification and documentation

Each shipment includes a dimensional inspection report. On request we supply material certificates to EN 10204 3.1, hardness results and a CMM printout for the batch.

• CMM dimensional report
• EN 10204 3.1 certificates
• Hardness and case-depth records
• Photographs before packing

What to send us

• A photograph of the machine nameplate, so we can confirm BC or EVOLUM and the size
• The position of the worn element on the shaft, or a photograph of the whole screw
• A photograph of the worn part with a rule in frame, or the OEM part number if it is legible

From those we confirm compatibility and quote before anything is machined.