Several advantages exist when using preformed adhesive epoxies instead of liquid adhesives, manufacturer of adhesive preforms Multi-Seals technical support manager Ken Harvill tells Engineering News.

He states that the biggest advantage of using preformed adhesives is that solid preforms remain so until they are heated, enabling epoxy to flow consistently onto the desired component, whereas liquid adhesives typically drip and dispense inconsistently onto unwanted areas of a component.

Multi-Seals’ US-manufactured Uni-form and Poly-form adhesive seals were both developed as alternatives to liquid adhesives.

The Uni-form is a one-part epoxy resin that is solid at room temperature. When heated, it melts and cures, forming a consistent seal to protect components from dust, moisture, oil, flux, industrial cleaning solvents, conformal coatings and other contaminants.

Meanwhile, the Poly-form is flexible before curing, which allows the manufacturer to produce larger and thinner adhesive configurations, says Harvill.

He notes other advantages of preforms are that they are premixed and have a consistent viscosity.

“This is because of a predetermined catalyst-to-resin ratio that produces a complete one-component system, resulting in predictable and consistent results, compared with variable mixed and metered liquid epoxy performance,” he explains.

Further, the viscosity of preforms remains consistent from seal to seal and batch to batch, whereas liquid epoxy continues to polymerise as it is dispensed, causing equipment clogs and variations in viscosity and seal quality.

The rapid manual and automated dispensing abilities of solid adhesives far exceed those of manually dispensed liquids, states Harvill.

Multi-Seals’ Uni-form adhesive, in particular, is well suited to a variety of automatic or semiautomatic sealing equipment dispensers such as templates, pick-and-place and bowl-fed gravity track methods.

Further, the solid adhesive enables simple cleanup.

Preform residue is easily swept up, while handling equipment needs to be wiped down only once or twice a week, says Harvill.

In comparison, liquid epoxy usually requires extensive cleanup procedures.

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