Many industries require the decorative elements of plastic to be highly durable. For instance, the aerospace, automotive, and medical industries have many high-wear applications that require strong, durable parts where printed icons won’t scratch off or fade away. Products that are decorated using first-surface decorating processes, where graphics are placed on the outermost layer (such as pad printing, screen printing, or hot stamping), wear out over time and aren’t suitable for these industries. Depending on the materials and processes used, the inks on plastic pieces can fade out over time, making it difficult or impossible to read indicators on those pieces.
What is in-mold decoration?
In-mold decoration (IMD) is a process where a graphic overlay is physically fused to injection molded plastic to form one piece. It is a plastic decorating method that ensures the durability of the graphic overlays and allows for multiple design options for the overlays. Molten resin is injected either in front or behind the graphic overlay to form a bond between the two. Unlike pad printing, screen printing, or hot stamping – where inks and overlays are exposed to the user that can deteriorate over time – IMD parts have a layer of plastic that encapsulates the ink, protecting it from users and the outside environment.
GM Nameplate’s (GMN) plastics division in Beaverton, OR, recently created a video that demonstrates the IMD process. In the video, we see an end-of-arm tool pick up a graphic overlay and place it in the injection mold using a vacuum system, while simultaneously removing a part that was just molded. Both of these functions are completed in one cycle, allowing for faster and more efficient production. Locating pins in both the end-of-arm tool and injection mold itself allow for consistent placement of the overlay in the tool, which is critical for functional parts in regulated industries. If the overlays are not correctly and consistently placed in the mold, some portions of the overlay may not be fully encapsulated by plastic during the molding process. To learn more about what the IMD process is, read this blog.
Advantages of in-mold decoration
In-mold decoration is ideal for higher volume projects that have stringent durability requirements, as there is more design engineering required up front than with a standard injection molded part. However, one advantage is that once the graphic overlay and molded part is designed, printed graphics on the overlay can be changed at any time to allow for customization and unlimited design options.
Explanatory video: In-mold decorating process
To watch the IMD process, click play on the video below.