An enclosure that’s rated IP67 on paper can still let moisture in at exactly one point — the seam where two housing halves meet — and that seam is almost always sealed with a bead of adhesive, not a molded gasket, once volume and geometry get complicated.
Q: Why use a dispensed adhesive seal instead of a cut gasket at all?
A cut or molded gasket only seals as well as the flatness of the two surfaces pressing against it, and it adds a discrete part that has to be sourced, inventoried, and placed correctly on every unit. A dispensed UV-curable seal follows any groove or irregular seam geometry exactly, fills machining and molding variance that a rigid gasket would bridge and potentially leak past, and removes a line item from the bill of materials entirely. For high-volume enclosure lines, that combination of geometric flexibility and reduced part count is usually the deciding factor.
Q: Does the seal go on before or after the housing closes?
Both approaches are used, and the choice depends on whether the enclosure needs to be reopened. Curing the bead before the housing closes leaves a resilient, compressible gasket that the closing housing squeezes into place — this suits battery doors, access panels, and anything with a defined service interval, since the housing stays serviceable. Curing after the housing is fully assembled bonds both surfaces into one sealed unit with higher pull-apart resistance and a better overall ingress rating, at the cost of making the enclosure effectively non-serviceable without cutting the seal open.
Q: What actually determines whether a bead-and-groove seal holds up outdoors?
Surface preparation determines whether the bead anchors at all — the housing surface has to be clean and dry, and low-surface-energy plastics often need plasma treatment before the bead will properly wet out and bond rather than just sitting on top of the surface. Bead volume control matters just as much: a starved bead leaves gaps, and a flooded one squeezes excess material into the enclosure interior or blocks a nearby feature, so volumetric or time-pressure dispensing control is standard on any line producing this seal at scale rather than a hand-triggered syringe.
Q: How does groove geometry affect seal performance?
A shallow rectangular or trapezoidal groove — roughly one and a half times as wide as it is deep — gives the bead a defined space to sit in, controls how much it compresses when the housing closes, and gives the cured seal a shoulder to react against under internal or external pressure. A flat land with no groove works adequately for low-pressure ingress protection but lets the bead spread unpredictably once the housing is closed, which is a common cause of inconsistent seal performance across a production run that otherwise looks identical unit to unit.
Q: What has to be verified before this seal design goes to production?
A qualification program for this kind of seal typically covers leak rate at the enclosure’s rated ingress-protection pressure, leak rate again after thermal cycling and a drop-test sequence representative of the product’s actual handling and shipping conditions, and resistance to whatever cleaning or environmental chemicals the enclosure will realistically contact in service. Email Us if you’re setting up a qualification plan for a new enclosure design and want help structuring the test sequence.
Q: Where does thermal cycling fit into seal reliability specifically?
An enclosure that sits outdoors or near a heat source cycles through a wide temperature range repeatedly over its service life, and the housing material and the cured adhesive seal rarely expand and contract at exactly the same rate. How CTE mismatch causes adhesive bond failure covers why that mismatch can gradually open a seal that tested fine at a single ambient temperature, and it’s a major reason thermal cycling belongs in the qualification sequence rather than being treated as optional.
Q: What equipment actually cures a seam like this in production?
Delivering a consistent UV dose along a bead that runs into corners and grooves takes some lamp planning specific to the part’s geometry. Matching a UV LED flood lamp to curing area and intensity covers larger, flatter seam geometries, while a spot-lamp light guide is often the better fit for a seam that runs through a tight or recessed corner a flood lamp can’t reach evenly. Formulations with a secondary cure mechanism are worth considering for any bead section that ends up in shadow regardless of lamp placement.
Q: What’s a realistic use case for this kind of seal?
Outdoor telecom and renewable-energy junction boxes, industrial sensor and controller housings exposed to washdown or weather, and consumer electronics enclosures needing an IP-rated seam without a separately molded gasket are all common applications where this dispensed-and-cured approach is the practical choice over a cut gasket, particularly once volume rises enough that gasket sourcing and placement become their own line-item cost.
Work With Incure
Send the housing material, groove or land geometry, and the ingress rating and environmental exposure the enclosure needs to survive. Contact Our Team for a grade and dispensing recommendation.
Visit www.incurelab.com for more information.