Tubes & Interfaces / Purchasing guide
A tube enquiry should identify which dimensions control the interface. Inside diameter, outside diameter and wall thickness are related, but they are not interchangeable purchasing instructions. Explain whether the tube fits over a shaft, inside a housing or into a clamp, and ask the supplier to review the complete dimensional requirement.
Catalogue reference image. Confirm the quoted configuration against the agreed drawing.
Start with the mating component
Provide the mating drawing where possible and say how the tube is assembled. A sliding fit, a bonded overlap and a clamped connection ask different questions. Identify the length over which the fit matters rather than giving only a diameter at an unspecified location. State the units and the drawing revision.
Identify the controlling requirements
Mark the dimensions that are essential to assembly and separate them from reference information. Avoid defining conflicting limits for inside diameter, outside diameter and wall thickness. If the design needs all three controlled, request a feasibility review and a clear statement of how the supplier will measure them.
Include the rest of the tube
Add cut length, end condition, straightness or alignment requirements where they matter to the design. Explain any machining, inserts or finishing required after the tube is formed. A quotation for an unprocessed length should not be compared directly with one for a finished assembly component.
Information to include in your enquiry
| Review item | Information to provide |
|---|---|
| Fit interface | Inside, outside or both surfaces |
| Length | Finished length and controlled fit region |
| Limits | Critical dimensions and agreed tolerances |
| Ends | Cut, machined or joined end configuration |
Frequently asked questions
Is nominal diameter enough?
It may identify a starting size, but a functional fit needs its acceptance limits and measurement location defined.
Can I specify only wall thickness?
Wall thickness alone does not identify the tube envelope or mating fit. Include the relevant inside or outside dimensions.
Discuss your carbon fiber component
Send your drawing revision, intended application, quantity and acceptance requirements to Litian Yunde for a project review.