Switching an existing RTV silicone sealing station to UV cure silicone isn’t a drop-in material swap — it’s a station redesign, and underestimating that is why some retrofit projects deliver less throughput gain than promised on paper.
What Stays the Same and What Doesn’t
The silicone chemistry itself — its flexibility, thermal range, and long-term environmental resistance — carries over largely unchanged between an RTV and a UV-cure grade of comparable Shore hardness. What changes is everything around the cure step: the fixture design, the floor layout, the operator workflow, and the quality-control checkpoints all need rethinking once cure time drops from hours to seconds.
Fixture and Layout Changes the Retrofit Actually Requires
An RTV line typically routes parts to a curing rack or a humidity-controlled room after the sealant is applied, with fixtures designed to hold a part stationary for hours. A UV cure retrofit removes that holding requirement almost entirely, but only if the light-exposure step is actually integrated into the dispensing station rather than tacked on as an afterthought — a UV cure station needs the light source positioned to reach every bonded surface, including any recessed or shadowed geometry the original RTV process never had to think about, since RTV cures uniformly regardless of light access. Retrofits that skip this step and simply add a UV lamp near an existing dispensing head, without redesigning for shadow-area coverage, are the ones that see disappointing throughput gains, because parts with any 3D geometry still need a secondary moisture-cure dwell for the areas light can’t reach.
The Dual-Cure Requirement for Real Parts, Not Flat Test Coupons
Most real assemblies aren’t flat, and any UV silicone retrofit needs to plan for a dual-cure mechanism from the start — a fast UV surface set for immediate handling strength, paired with a slower secondary moisture or heat cure that finishes the reaction in shadowed regions over the following hours. Skipping this and assuming a single UV pass fully cures a complex 3D part is the single most common cause of early adhesion failures reported after a retrofit, since the shadowed section never fully cures and eventually releases under load or vibration.
Requalifying the Process, Not Just the Material
An RTV process qualified against cure time, humidity, and ambient temperature needs an entirely different qualification protocol for UV cure — spectral match between the lamp and the photoinitiator package, irradiance uniformity across the bond geometry, and total dose delivered to both exposed and shadowed regions. A facility that requalifies the silicone material but reuses its old RTV process-control checklist unchanged is missing the parameters that actually determine whether the new process works.
Retrofit Economics: Where the Payback Actually Comes From
The throughput gain from a UV retrofit comes almost entirely from eliminating the multi-hour cure-rack dwell time, which frees both floor space and work-in-process inventory that an RTV line ties up for the length of its cure cycle. The gain does not come primarily from the sealant application step itself, which takes roughly the same time under either chemistry. Facilities that model the retrofit’s payback purely on faster application speed rather than eliminated dwell time and floor space tend to underestimate the actual return, since the dwell-time elimination is where most of the value lives.
Email Us if you’re scoping a retrofit and want help estimating the floor-space and work-in-process inventory reduction specific to your current RTV cure-rack footprint.
Operator Retraining the Retrofit Plan Should Include
Operators accustomed to an RTV process where a slightly imprecise bead gets corrected during a long open working time need retraining for UV cure’s much shorter positioning window — parts have to be aligned correctly before the light triggers cure, since there’s no equivalent to RTV’s hours-long adjustment period. A retrofit plan that budgets for equipment cost but not for this retraining period tends to see a temporary defect-rate spike in the weeks immediately following changeover, before operators adjust to the faster pace.
Substrate and Cleanliness Considerations That Carry Over Unchanged
Substrate cleanliness matters identically under both chemistries — oils, mold-release residue, and dust interfere with wetting regardless of cure mechanism — so a facility’s existing substrate-prep standard generally transfers to the new process without modification. This is one of the few retrofit elements that genuinely doesn’t need rework. For background on the underlying photo-initiated cure chemistry and technical specifications common to this material category, see our companion guide on UV cure silicone, and for related guidance on matching light source wavelength to a resin’s photoinitiator package, what a light guide is in a UV spot lamp system is a useful reference for stations routing light through fiber or liquid guides.
The Retrofit Decision in Summary
A UV cure silicone retrofit pays off fastest on lines currently bottlenecked by RTV cure-rack dwell time and floor space, and pays off more slowly on lines where application speed, not cure time, was already the limiting factor. Incure’s engineering team can help model a specific line’s retrofit economics and flag shadow-area geometry that will need a dual-cure plan before equipment is purchased. Contact Our Team to review a retrofit plan for your current sealing station.
Visit www.incurelab.com for more information.