Most carbon tube returns are not quality issues. They are tolerance mismatches between the tube and the mating part.
Where tolerance matters most
|
Dimension |
Typical spec |
Why it matters |
|---|---|---|
|
OD |
±0.05mm |
Slide fit, press fit, bearing seat |
|
ID |
±0.1mm |
Insert clearance, mandrel removal |
|
Length |
±0.1mm |
Butt joint, flange face, end stop |
|
Wall |
±0.1mm |
Stiffness, weight, crush resistance |
Fit types
Slide fit: OD +0.05mm / −0.00mm, smooth surface, no chamfer interference
Press fit: OD +0.10mm / +0.15mm over mating bore, requires controlled insertion
Clearance fit: OD −0.10mm to −0.20mm, for inserts or sleeves
What buyers forget
Chamfer size at both ends - without it, press fit starts crooked
Datum face - length tolerance is meaningless without a reference plane
Batch variation - first article may pass, batch 4 may drift if cure shrink is not controlled
RFQ checklist
Send OD, ID or wall, length, chamfer size, tolerance class, mating material, fit type. We match layup and cure to hold the numbers.
FAQ
Q: Can you hold ±0.02mm on carbon tube OD?
A: Possible on small batches with grinding, but not economical for CNC-trimmed tubes. ±0.05mm is the standard precision grade.
Q: Does temperature change tube size?
A: Carbon has very low CTE, but epoxy softens above 80°C. Keep assemblies below that in operation.
Q: How do I specify a press fit?
A: State bore size, tube OD, chamfer angle, insertion force limit. We adjust OD and surface finish.
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