Medical Device Housing DFM: Molded and Machined Enclosures
Medical device housings must be moldable or machinable at volume, cleanable in the field, and traceable for regulatory records. This article focuses on DFM for plastic and machined housings — the mechanical decisions that reduce scrap, rework, and supplier disputes.
Plastic vs Machined Metal Housings
Injection molding: Best at volume, complex organic shapes, integrated snaps. Requires draft, uniform walls, and mold validation.
CNC / sheet metal: Better for low volume, rigid structural needs, EMI shield integration. Watch sharp internal corners (machinability) and anodize/coating compatibility with cleaning agents.
Many devices combine both: molded clamshell + machined aluminum spine or heat spreader.
Sterilization-Aware Design
EtO, gamma, and autoclave methods stress materials differently. Polycarbonate may yellow under gamma; some LSRs handle autoclave cycles. Design material cards listing max temperature, chemical exposure, and biocompatibility status.
Avoid hollow chambers that trap sterilant unless validated. Provide drain paths or sealed volumes explicitly in drawings.
Labeling, UDI, and Part Marking
Plan recessed areas for labels and laser-marked UDI — not on curved surfaces below minimum radius for readable marks. Molded-in symbols (recycle, warnings) need draft and depth specs readable after fill.
Part numbers and revision levels on hidden surfaces help manufacturing traceability without hurting UX.
Verification Before Tooling
Run sealing tests (IPX, submersion per your spec), drop tests on representative assemblies, and cleaning compatibility swatches on finished surfaces. Capture results in verification reports linked to design outputs.
Use tolerance stackups on latch engagement and gasket compression — medical devices often need 30–50% gasket compression without over-stressing plastic flanges.