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Overmolding refined

Fabrics have long been insert molded into parts such as automotive floor panels, door liners, and seat components. The usual approach is to insert fabric or carpet in the tool and then back it up by injecting plastic behind it. But fabric-plastic moldings generally don’t achieve quality standards required for consumer enclosures, often showing wear and fraying at the edges. Also, it is critical in electronic enclosures that the fabric be isolated from the interior, since encroachment can cause short-circuits or compromise compliance with UL flame-resistance requirements.

Tarnowski says the EXO process addresses those deficits. It begins by creating fabric blanks or preforms. These are reinforced with laminated film and adhesive backings that minimize fabric degradation, wrinkling, or misalignment during overmolding. The fabric blanks can be used either as flat inserts or can be thermoformed into 3D shapes for more complex applications.

Next, the preforms are loaded robotically into a standard two-shot molding system. The first shot is typically a rigid material that provides a solid backing for the fabric. The second shot overmolds the edges of the preform to seal the perimeter of the fabric (preventing wear at exposed points) and to incorporate molded-in anchors that more firmly fix the fabric in place. This second shot can be of a different (softer) material and/or color. It also opens the door to improved functionality, says Tarnowski. For example, overmolded layers can act as gaskets to provide a water-tight seal.

Inclosia Solutions has set up design and engineering bureaus in the U.S. and the Netherlands, and it plans to add a third in Asia shortly. The company offers electronics OEMs a one-stop source for design, material selection, tooling, prototyping, assembly, and production. For this purpose, Inclosia Solutions has formed a collaborative alliance with Eimo Oyj in Lahti, Finland, a designer and molder of enclosures for telecommunications.