Expanding Small Diameter Tubing
Small Tube Expanding
Small diameter tube expanding is similar to flaring in the sense that it is a controlled metal-forming process used to increase the internal and external diameter of small, thin-walled tubing while maintaining structural integrity, consistent geometry, and clean surface finish required for medical, laboratory, and precision-fluid applications. The expansion process must be executed with precise tooling and carefully managed force to avoid cracking, wrinkling, or excessive wall thinning.
The operation typically involves inserting a mandrel, tapered pin, or segmented expansion tool into the tube’s bore and applying axial or radial force to gradually enlarge the diameter to a predetermined dimension. Prior to expanding, the tube end must be cut cleanly, deburred, and free of contamination to ensure uniform deformation and to prevent scoring the tool. During forming, controlling the rate of expansion is critical; rapid displacement can introduce localized stresses, while controlled, incremental expansion promotes even material flow and reduces the risk of microstructural damage.
Depending on the alloy, wall thickness, and final diameter required, expanding may be conducted cold or with an annealing process to improve ductility and reduce work hardening.
Post-expansion quality checks typically include dimensional inspection of inside and outside diameters, roundness, straightness, and surface condition, as well as visual inspection for cracking, orange-peel texture, delamination, or other signs of deformation failure.
Advances in mandrel design, servo-controlled forming equipment, and in-process measurement systems have improved consistency by allowing tighter control of force, displacement, and material response, reducing operator variability and improving yield.
Hypodermic tube expanding is a key manufacturing technique that enables small diameter tubing to be integrated into components requiring larger internal diameters, stepped transitions, or custom interfaces, supporting the development of high-precision, reliable, and safe fluid-handling assemblies.
New England Small Tube also offers Buffing and Electropolishing for smooth surface finishing.
Contact us today to discuss how these processes can improve your part performance
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