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. Aluminum Casting.
Many features in aluminum casting can be made in the cast, but critical features must be machined as a secondary operation. RIM allows these features to be molded in for reduced handling and reduced cost. Both methods allow for variable wall thickness—down to 0.60” for aluminum casting, and from 0.12” to 1.12” in RIM. Another major difference is appearance quality. A grinder is used for cleanup in aluminum casting, while RIM Molding delivers an excellent finish out of the mold.
Materials cannot be encapsulated with aluminum casting. Only RIM can encapsulate metals, electronics, and other parts for optimum protection and strength. Compared to RIM, the finish quality of aluminum cast parts is low; and RIM can take paint, silk screening and texturing better for improved branding.
Both processes are appropriate for small run volumes, but are not cost-effective when dealing with larger quantities (over 500/mo.). RIM tooling lead times are shorter than for aluminum casting. Both RIM and aluminum casting require a low up-front cost, although RIM is slightly more cost effective if tooling modification will be needed.
Another Design Consideration: With RIM, you can create very large, light-weight, low-cost parts that would otherwise be limited in design with aluminum casting.
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