The design of gaskets comes in a nearly unlimited number of component arrangements and material combinations from which they inherit their properties. As a result, gaskets can be classified in various ways ranging from the category of the utilized materials to the function and application of the resulting gaskets.
Gaskets can also be classified according to their manufacturing/ application processes. Specifically, they can fall in one of two categories:
- Conventional compression gaskets, also called pre-formed gaskets, are engineered elastomers cast in a custom shape, size, and thickness designed for particular applications. Resin Designs brand GelTek Silicone GT gels are perfect examples of high-performance compression gaskets.
- Form-In-Place (FIP) gaskets, on the other hand, are liquid resins, which can be directly applied onto various types of substrates. This uncured resin can then be polymerized, forming the elastomer gasket directly at the intended interface.
Some applications may be better suited by one type of gasket over the other. This post is dedicated to explaining some of the basic properties and practical benefits of form-in-place gaskets.
FIP vs. Pre-Formed Gaskets
FIP gaskets could be comprised of various base materials (epoxy, silicone, urethane, acrylate, etc.) and have the ability to cure via the following mechanisms:
- Room temperature vulcanizing silicones
- Room temperature two-part resins
- Moisture sensitive urethanes
- Anaerobic resins
- UV curable acrylates
The suitability of each method strongly depends on the intended application.
Ultimately, FIP gaskets offer a wide range of benefits such as:
- Elevated sealing strengths because they are formed and cured in place
- Improved reliability on account of their abilities to adapt and fit into various sizes, forms, and shapes
- Minimum waste and cost saving as the material is dispensed directly onto the work piece
- Require fewer inventory space since they could be stored as uncured liquids and not in pre-formed gaskets of various shapes and sizes
- Quick lead times where they cure fast and can be made automatically, which make them suitable for large scale production
- Easy to apply as one single combined component
- Reduced servicing costs because they could be assembled/ disassembled and cleaned up easily
- Adhere reliably to various types of substrates such as metal alloys and conductive/ painted plastics
Conventional pre-formed gaskets, on the other hand, are primary choice for customers looking for:
- Instant pressure seal customized to meet their needs
- Minimal tooling since the gaskets are already pre-formed
- Precise bond line thickness and dimensions
Curing FIP gaskets through Ultraviolet (UV) light
Ultraviolet (UV) light sensitive resins can be utilized to create instant setting FIP gaskets.
UV curable resins are one-part systems formulated with chemical species known as photoinitiators, which, when exposed to the correct radiation wavelength, will break down into highly reactive free radical species. These free radicals then initiate a fast chain-growth reaction, normally completing the polymerization in a matter of seconds.
UV curable FIP gaskets normally cure to form soft elastomers. The following products are examples of high performance UV curable FIP gaskets:
- Vivid Cure 70201 is a low viscosity UV acrylate resin. After proper application to the intended substrate, UV light (365, 405nm recommended) will polymerize the resin within seconds. The resulting soft elastomer material provides excellent moisture and vibration resistance, as well as selective release from bonded or coated substrates.
- Vivid Cure 70211 is a higher viscosity UV acrylate resin. This thixotropic formulation provides alternative assembly properties to the Acura 70201 sister product. Despite the modified flow properties, Acura 70211 will also polymerize within seconds to form an elastomer with exceptional sealing and gasketing properties. Relevant properties include high elongation, selective release, and intermittent high temperature resistance.
Curing FIP gaskets through UV radiation offers of range of benefits that includes:
- Increased energy efficiency as it eliminates the need for curing ovens and post-cure processes
- Increased production speeds due to the “set on demand” curing process that only requires a few seconds or minutes even when the gaskets are made thick
- Increased seal durability even in most harsh environmental conditions like elevated temperatures, shock, vibration, crack, and exposure to chemicals such as strong acid/bases
- Decreased footprint of in-process components associated with oven curing methods
- Decreased waste as meter mixing, adjusting, and purging are only necessary for two part systems
- Decreased costs related to design, inventory, dispensing equipment, testing, floor-space, and labor
- Decreased environmental impact due to the environmentally friendly and non-polluting photo-polymerization process. Free radical polymerization results in no volatile losses. Other curing methods, however, release a number of organic additives and hazardous solvents during the curing process. UV FIP gaskets are, hence, suitable for green energy devices
Common applications of UV curable FIP gaskets
The principal function of UV curable FIP gaskets is to provide a robust seal throughout the lifetime of the application. Because of the superior features of UV FIP gaskets, they are currently employed in a wide range of applications across various industries including:
- Electronic devices and assemblies such as mobile cells phones, laptops, and computer components
- Automotive appliance casting and parts such as wheels and doors
- Speaker components and assemblies
- Sound dampening
- Device coatings
- Electrical closures and conduit boxes
- Fuel cells
- Appliance castings and housings requiring sealing for large pieces with less force and resin
- Filters for various industries
- HVAC sealant and ductwork
- Underwater enclosure equipment
- High-temperature sealing components