C338/U-D Rotor Complete
U-groove rotor complete for flexible medium-to-coarse spinning (Ne 10–30) on the Rieter R923 and R35 semi-automatic platform. Diamond-coated working face. T013 bearing rated to 110,000 rpm with a recommended ceiling of ≤ 90,000 rpm — dimensionally identical to the original, at 40–60% below OEM price.
C338/U-D — Complete Specifications
All measurements in millimetres. Every rotor complete assembly is 100% dynamically balanced on our own balancing line before shipment.
Why U Groove for General-Purpose Spinning
The U groove is the general-purpose profile: a wider deposition zone that handles medium to coarse counts (Ne 10–30) across a wide range of fibres without changing rotors between lots. The model is selected on the application, so the bearing fit and the count window are confirmed together.
U Groove — Applicable Yarn Count Range
Suited to medium-coarse counts. For fine counts (Ne 30–40), the T groove is the tighter match. Send us the fibre type and target count with the enquiry and we confirm the pairing.
U Groove — One Rotor, Many Counts
The wider U geometry gives a broad operating window in the Ne 10–30 band, so a single rotor covers more of the count schedule. That means fewer change-outs between lots, less spindle downtime and simpler spare-part stocking. The wider window is what makes one rotor serve a mixed schedule, at the cost of some fine-count control.
Tolerant of Fibre Change
General-purpose geometry absorbs the variation that comes with running several raw materials on one line.
One Rotor, Several Orders
Mixed-order mills can keep the same rotor in place as the schedule moves inside the band.
Straightforward Economics
A flexible rotor that reduces both change-out labour and the number of lines carried as spares.
Wide Count Window (Ne 10–30)
A broad operating band means fewer rotor changes when the count schedule shifts, cutting machine downtime.
What D 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. The D in the code is the diamond top layer — the face that takes the fibre and grit contact. On the -BD- models that same layer sits on a boronized base. The rotor is dimensionally identical to the original part, so no machine modification is needed.
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. This code does not carry the B step; it is the -BD- variant that pairs the diamond layer with the boronized base.
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 C338/U-D?
The T013 bearing fixes this rotor to the Rieter R923 and R35 semi-automatic platform. It is one of 9 rotor models sharing that bearing group.
What to Spin with C338/U-D
Typical operating profile for the U groove on the Rieter R923 and R35 semi-automatic platform, at speeds up to 110,000 rpm.
✓ Schedule flexibility with fewer rotor changes
✓ Mills wanting a simple, low-inventory spare-parts line
✓ General-purpose profile, medium to coarse yarns
◇ Strictly single-count fine spinning — XTC extra-narrow
◇ Fine yarns Ne 30–40 — T narrow family
◇ Blends and speciality fibres — S groove
→ T: Narrow (Ne 16–40)
→ TT: Extra narrow (Ne 16–40)
→ S: Special (Ne 16–40)
→ U: General purpose (Ne 10–30) — this model
→ GL: Large (Ne 3–16)
→ See all 9 Rieter R923 and R35 rotor models →
C338/U-D — 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 C338/U-D compatible with my Rieter R923 and R35 machine?
What does the model code C338/U-D mean?
What yarn counts does the U groove suit?
What do the letters BD mean in the model code C338/U-D?
How much does an OEM-equivalent rotor save versus the original?
Can I order the rotor spindle or rotor cup separately?
Order C338/U-D Rotors
Pre-filled: C338/U-D · Rieter R923 / R35 · diamond coating
Tell us your quantity and we respond with pricing, lead time and freight options within 24 hours. Sample orders welcome.
No spam · Your information stays private · Leo Wang replies personally