Inclosia Solutions just last year introduced a way to incorporate real wood, metal, leather, or fabric into injection-molded parts. This EXO Overmolding system gave electronics enclosures and other molded plastic products a craftsman-like appearance while avoiding the need for costly craftsmen. Now, the company has upped the style ante for mass-produced parts once again.
Its new EXO Mix technology combines two or more of these decorative materials on the same part surface—and does so without visible seams between them. "The key feedback from our customers is that they wanted to use not just one but a combination of authentic materials on the same part," says Inclosia manager Tom Tarnowski.
Inclosia had to overcome a number of technical hurdles to create seamless transitions between materials of different thicknesses and coefficients of linear thermal expansion. "We had to draw on all of our materials science and processing knowledge to make it work," says Inclosia technical leader Mike Hus.
Hus explains that this knowledge starts with picking the right adhesives to bond the EXO Mix materials to each other and to their plastic substrate. He won't say much about the type of adhesives other than to say some are proprietary products from Dow Plastics, Inclosia's parent company. Hus reports that Inclosia is currently conducting adhesion tests for a wide variety of substrates and decorative materials under different thermal and environmental conditions.
EXO Mix also requires careful attention to how the fabric, wood, or metal layers are cut—and often stacked—to form an insert for the multi-shot injection-molding proc-ess. Hus says the edges between materials may look like a perfect butt joint between adjacent materials, and sometimes they are. But more often, Inclosia stacks the decorative materials to form a laminate structure. Using lasers or precision dies, it then selectively cuts away one or more top layers to reveal what's underneath.
To make all these revealed and top layers flush on the final part, Inclosia relies on the compression of the molding process and also intentional variations in the wall thickness of the plastic substrate. The same two factors also adjust for any differences in thickness between adjacent decorative materials in those cases where the insert is one layer thick.
All of this complex bonding takes plenty of upfront work, but it pays off in the finished part. "It drops from the molding machine in one cycle with all of the authentic materials on it," Tarnowski says.
For more information on overmolding technology, check out the link below: