31-XT-BD-AE Rotor Complete
Narrow-groove rotor complete for fine and medium-fine yarns (Ne 16–40) on the Rieter R40 fully automatic platform. Boronized (boron-steel) base with a diamond working face. Every assembly is dynamically balanced and vibration-checked before shipment, at 40–60% below the OEM part price.
31-XT-BD-AE — Complete Specifications
All measurements in millimetres. Every rotor complete assembly is 100% dynamically balanced on our own balancing line before shipment.
Why XT Groove for Fine Yarn
The narrow T groove is calibrated for fine and medium-fine counts in the Ne 16–40 band — the range where fibre deposition control, not rotor volume, decides yarn evenness. The group is stocked across several cup sizes, which lets a mill shift counts without changing the spinning-box setup.
XT Groove — Applicable Yarn Count Range
Aim this groove at the fine half of the range. Coarse counts in the Ne 3–16 band need the wider GL profile. Coating grade and count band are confirmed with the quotation for this rotor.
XT Groove — Precision Fibre Control at Fine Counts
The narrow groove creates a compact deposition zone inside the rotor, so fibres are distributed and twisted evenly right through the fine count range. The result is higher yarn evenness and fewer thin and thick places — the properties fine knitting and shirting yarns are judged on. The profile is intended to be run at the fine end of the schedule and swapped out at the coarse end.
Better Evenness at Fine Counts
Tighter deposition control is what holds thin and thick places down when the yarn gets fine — the effect buyers notice first.
Lower Break Rate
Smoother twist propagation at fine counts cuts the tension peaks that break ends at high rotor speeds.
Resists Micro-Dust
A compact, smooth cross-section leaves fewer pockets for micro-dust, so fault frequency stays flat over a long doff.
Thin-Place Reduction
Control of the deposition zone directly limits the thin places that downgrade fine knitting yarn.
What BD Means: Base and Working Surface
The trailing letters of the model code are two independent codes, not one word: B is the substrate, D is the working surface. B and D do different jobs — B hardens the base, D takes the wear. Tell us your fibre and the speed you run and we confirm both before a bulk order. Ordering rotors, bearings and opening rollers together keeps freight and coating consistent across the spin box.
B = boronized (boron-steel) substrate. A diamond film is only microns thick, so the steel underneath decides whether it survives: a soft substrate deforms under fibre and grit impact and the film cracks and spalls off. The boronized base is the hardening step that keeps the diamond layer intact.
D = diamond top layer, grown on the prepared substrate as a micron-scale film. It takes the fibre and grit contact directly, which is where the wear resistance, the friction coefficient of 0.05–0.1 and the anti-stick behaviour come from that hold the groove profile over long runs. Diamond coating technology of US origin, applied on JSM’s own treatment line.
Which Rieter Machines Use 31-XT-BD-AE?
R40-AE is the bearing standard for this rotor on the Rieter R40 spinning box. A rotor from another group will not seat correctly.
What to Spin with 31-XT-BD-AE
How this rotor is normally applied on Rieter R40 machines, with the XT groove’s published count window where the catalogue documents one.
✓ Fine knitting and shirting-type yarns
✓ Mills whose count schedule sits above Ne 20
✓ Narrow-profile spinning where evenness is the priority
◇ Extremely fine compact counts — XTC extra-narrow groove
◇ Abrasive or recycled fibre — DN diamond coating
◇ Medium counts below Ne 16 — G standard or U general purpose
→ TT: Extra narrow (Ne 16–40)
→ S: Special (Ne 16–40)
→ U: General purpose (Ne 10–30)
→ GL: Large (Ne 3–16)
→ G: Standard (Ne 16–40)
→ See all 9 Rieter R40 rotor models →
31-XT-BD-AE — Frequently Asked Questions
Answers to the questions buyers ask most often about this rotor. If yours is not listed, send it with your machine model and current rotor code — we reply within 24 hours.
Is 31-XT-BD-AE compatible with my Rieter R40 machine?
What does the model code 31-XT-BD-AE mean?
What yarn counts does the XT groove suit?
What do the letters BD mean in the model code 31-XT-BD-AE?
How much does an OEM-equivalent rotor save versus the original?
Can I order the rotor spindle or rotor cup separately?
Order 31-XT-BD-AE Rotors
Pre-filled: 31-XT-BD-AE · Rieter R40 · boronized base + diamond coating
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