Continuing our exploration of the right molding process for part design (“Determining the Right Molding Process for Part Design”), this blog entry considers RIM Molding vs. Fiberglass.
While fiberglass can be used to produce very large, stiff parts, reinforced RIM parts can offer the same advantages with less labor for a lower unit cost. Traditional fiberglass molding is a slow, manual and labor intensive process, and issues of conformity and accuracy can often arise in these parts. The RIM process can produce more uniform parts with features molded into the interior. Fiberglass is the best option for prototyping very large parts, although it is possible to mold fibers into a RIM part to gain the strength and
weight advantage of fiberglass. Both processes provide a solution for encapsulating metal, but only RIM urethane is appropriate to use when encapsulation of PCBs and other electronics is necessary.
Fiberglass parts can have a high quality finish, but RIM parts are easier to paint for improved branding.
Fiberglass is mostly used to make small quantities of prototype parts. RIM is more cost-effective for actual production of low volumes (25-500 parts/mo.) compared to fiberglass. Neither process is the appropriate for higher production volumes. Both RIM and fiberglass tools require a low up-front cost, and both types of tools allow for cost-effective modification if market feedback shows that features need to be changed.
Other Design Considerations: Fiberglass production emits large amounts of hazardous styrenes. RIM is a much more environmentally safe “green” option compared to fiberglass.
Coming up next: RIM Molding vs. Sheet Metal