Medical Catheter Mechanical Design: Hubs, Bonds, and Mold-Ready CAD
Catheter and fluid-delivery subassemblies sit at the intersection of precision mechanics, molding, and regulatory documentation. Mechanical engineering here is not "just CAD" — bond lengths, hub retention, and flexible section control drive moldability and inspection. This article covers parametric modeling and tolerance choices that keep catheter programs moving.
Parametric Master Models for Device Families
One catheter platform often spans multiple lengths and French sizes. Build a single parametric master with published drivers (working length, hub OD, luer interface) rather than copying files per SKU. Use configurations or equivalent design-table workflow so mold vendors always quote the same tree.
Document which dimensions are clinical vs manufacturing — only manufacturing controls need appear on mold drawings.
Hub Retention, Bonds, and Mold Shutoffs
Hub-to-shaft retention must survive pull tests and sterilization cycles. Define bond length, flash control, and shutoff angles for the mold vendor early — retrofits are expensive.
Tolerance stack: Model worst-case bond length with shaft OD tolerance and hub bore. RSS helps when distributions are known from molding SPC.
Materials: Document resin grades on drawings; flag patient-contact surfaces for biocompatibility pathway (ISO 10993 as applicable).
Drawings and DHF-Ready Documentation
Release controlled 2D drawings with revision tables, material specs, and inspection dimensions on critical features. Section views showing mold shutoffs reduce RFQ loops.
Pair mechanical release with risk-file references (ISO 14971) at the document level — mechanical owns geometry; quality owns hazard linkage.
Verification Before Mold Cut
First-article inspection on hub bond length, pull force, and visual flash criteria should be defined before tooling. Ohmframe supports medical mechanism CAD, tolerance analysis, and production drawing packages for catheter and handheld device programs.