Reaction injection molding offers a similar production method to the more traditional injection molding. However, the process is desirable for an upgrade in quality. Where as injection molding is used for everything from CD cases to shampoo containers, manufacturers may use RIM for the production of automotive elements (including bumpers, fenders, panels and other exterior areas of the vehicle).
One area of concern some manufacturers may have is the color variety. Where injection molding allows for just about any color of plastic, does RIM allow for this, and if not, is there a workaround option?
Understanding Reaction Injection Molding
Before looking into the color variety options available in RIM, understanding the process of RIM is important. During the initial stages, two parts of polymer are mixed together. This mixture is injected into the mold using a higher pressure impinging mixer. Unlike plastic injection molding, which either instantly cools or is dipped into a cool liquid to speed along the process, RIM must sit in the mold longer, allowing the polymer mixture to solidify and cure. This overall process allows any imperfections to be worked out of the solid, which is extremely important when it comes to automotive parts. Air pockets and bubbles can prove problematic and even result in possible safety issues. During the curing process, an additive is commonly used, including mica or fiberglass. This provides a more rigid, secure nature to paneling. It also remains lightweight, so while some metals are available for the process, it typically utilizes a lighter weight material.
Color Options Available]
Due to the polymer mixture involved with RIM, not all color options are initially available during production. Some basic, initial color options are available, yet pigments used to produce certain color tones contain chemicals not supported by the polymer mixture. Due to this, most manufacturers choose to paint the finished product later. This, in turn, makes it easier to mass produce a single bumper, fender or piece of paneling, regardless of the final color.
RIM does accept paint exceptionally well, so there is no issue with running or streaking during the paint process. It also opens up the possibility of changing paint requirements based on particular needs for the company (which likely shift at a moment’s notice).
For individual color options offered during product, contacting the RIM service provider is necessary. In terms of inexpensive alternatives though, painting after completion is typically recommended.