31-XT-BD-EC Rotor Complete
Narrow-groove rotor complete for fine and medium-fine yarns (Ne 16–40) on the Rieter R40 fully automatic platform. BD build — boronized base under a diamond top layer. 100% dynamically balanced and dimensionally identical to the original — at 40–60% below OEM price.
31-XT-BD-EC — 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
Narrow-profile geometry is the fine-count answer. The T groove concentrates deposition into a compact zone so the fibre bundle is twisted evenly at the top of the count range. 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
Optimized for fine and medium-fine counts in the Ne 16–40 band. Below that band the narrow geometry starts to restrict fibre flow. Mills usually run a sample first to verify the groove on the machine before a bulk order.
XT Groove — A Tight Zone for a Thin Ribbon
Narrow grooves trade operating width for control, and the T profile makes that trade deliberately: inside Ne 16–40 the tighter zone produces steadier fibre separation and a yarn that holds its appearance through downstream processing. Narrow grooves are only worth their tighter tolerances when the count schedule justifies them.
Tuned to Ne 16–40
A narrow zone matched to thin fibre ribbons keeps collection stable across the whole fine-count band.
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.
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. Standard lead time on coated rotors is 7–15 days, with urgent orders on request.
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-EC?
R40-EC 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-EC
How this rotor is normally applied on Rieter R40 machines, with the XT groove’s published count window where the catalogue documents one.
✓ Cotton, viscose and modal at the fine end
✓ Fine knitting and shirting-type yarns
✓ Mills whose count schedule sits above Ne 20
◇ Abrasive or recycled fibre — DN diamond coating
◇ Medium counts below Ne 16 — G standard or U general purpose
◇ Blends and speciality fibres — S groove
→ GL: Large (Ne 3–16)
→ G: Standard (Ne 16–40)
→ T: Narrow (Ne 16–40) — this model
→ TT: Extra narrow (Ne 16–40)
→ S: Special (Ne 16–40)
→ See all 4 Rieter R40 rotor models →
31-XT-BD-EC — 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-EC compatible with my Rieter R40 machine?
What does the model code 31-XT-BD-EC mean?
What yarn counts does the XT groove suit?
What do the letters BD mean in the model code 31-XT-BD-EC?
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-EC Rotors
Pre-filled: 31-XT-BD-EC · Rieter R40 · boronized base + diamond coating
Tell us your quantity and we respond with pricing, lead time and freight options within 24 hours. Sample orders welcome.
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