A seal’s integrity can determine whether an entire assembly succeeds or fails in the field, and traditional die-cut gaskets or room-temperature-vulcanizing silicones often can’t keep up with modern production demands. Light-Curable Form In Place Gaskets (FIPG) combine liquid dispensing with rapid light curing to close that gap.

Understanding the Mechanics of Light-Curable FIPG

These gaskets start as liquid resins — typically acrylated urethanes or silicones with photoinitiators mixed in — dispensed directly onto a part’s surface. Exposure to a specific wavelength, usually 365nm to 405nm, triggers rapid cross-linking that transforms the bead into a resilient elastomer in seconds, allowing immediate assembly and testing rather than a long moisture-cure wait.

Key Technical Specifications

Viscosity and thixotropy matter most for maintaining bead shape and height right after dispensing, before the cure cycle locks it in place. Shore hardness, generally Shore OO to Shore A, sets compressibility — softer grades allow sealing under lower bolt loads, useful for plastic or thin-walled housings. Compression set below 20% is a common benchmark for long-term reliability, especially where thermal cycling is routine, and adhesion strength can be tuned for either compression-only or seal-and-bond designs depending on whether the gasket needs to bond to metal, glass, or engineered plastics. Thermal stability across -40°C to +150°C is standard for industrial applications, and formulations rated for the upper end of that range typically hold their compression set even after repeated thermal cycling, which matters more for long-service equipment than a single cold or hot-day test would suggest.

Critical Industrial Applications

Electronics and micro-assembly manufacturers use light-curable FIPG to seal smartphone housings, handheld scanners, and outdoor telecommunications equipment, often targeting IP67 or IP68 water and dust ratings without the long tack-free wait that traditional sealants require. Automotive systems rely on FIPG to seal ECUs, sensors, and battery management units housed in complex enclosures, where resistance to engine fluids and vibration damping both matter. Aerospace and defense applications use form-in-place gaskets to eliminate heavy mechanical fasteners in some sealing roles, compensating for surface irregularities in machined components while resisting jet fuel and hydraulic fluid exposure. Renewable-energy inverter and junction-box manufacturers have adopted the same approach for weatherproofing outdoor enclosures at scale, and rail-transit equipment builders use it for sealing control-panel housings exposed to weather and vibration over long service intervals.

Performance Advantages Over Traditional Methods

Die-cut gaskets require maintaining stock for every unique part design; a single liquid FIPG material can cover hundreds of gasket profiles, cutting inventory costs and lead times substantially. RTV silicones often need 24 to 72 hours to reach full properties, while light-curable materials cure in seconds, enabling just-in-time manufacturing and immediate leak testing. Die-cutting can waste up to 70% of material, whereas automated FIPG dispensing places material only where needed. FIPG can also follow complex three-dimensional curves and varying heights that would be difficult or prohibitively expensive with a pre-manufactured seal.

Optimizing the Curing Process

Matching the light source’s spectral output to the resin’s photoinitiator absorption profile is essential for a consistent, repeatable cure. UV LED systems have become the preferred choice for FIPG work: monochromatic output around 365nm, cool operation that protects heat-sensitive substrates, and consistent intensity across tens of thousands of hours. What causes UV light guide degradation over time is worth reviewing for teams running high-duty-cycle dispensing lines, since delivery-optics wear can quietly undercut an otherwise well-tuned process. Shadowing — areas of the bead blocked from light by part geometry — is handled with transparent substrates, optimized light-array angles, or dual-cure formulations that add a secondary moisture or heat mechanism.

Email Us to discuss bead design or dual-cure options for a challenging enclosure geometry.

Design Guidelines and Automation

Groove or “well” designs help contain the material and define the final gasket shape while allowing light penetration. Bead height-to-width aspect ratio needs careful control, since a bead that’s too tall may tip before curing and one too thin may not compress enough to seal reliably. Surfaces should stay free of oils and mold-release residue, with plasma or corona treatment applied to hard-to-bond plastics like polypropylene where needed, and compression stops in the assembly design prevent over-compression that leads to material fatigue. Which UV glue is better for transparent bonding covers related substrate-transmission principles for teams using transparent housings in the gasket design. High-speed XYZ dispensing robots paired with an in-line UV LED station can complete the entire dispensing-to-cure sequence in under 30 seconds, reducing labor costs and scrap rates while improving repeatability.

Light-Curable Form In Place Gaskets solve the bottlenecks that come with traditional gasketing, combining liquid-dispensing flexibility with the speed of light curing. As material science pushes toward higher thermal conductivity and improved flame retardancy, this approach keeps expanding into more demanding sealing applications. Contact Our Team to discuss material selection and process validation for your sealing challenge.

Visit www.incurelab.com for more information.