Two-shot molding, dual-shot molding, multi-shot molding, two-color molding, double-shot molding, dual-material molding…
Whatever you choose to call it, this type of molding process involves combining two or more resins or materials into one part. Molding manufacturers who are skilled and experienced with this type of process are capable of producing high-quality, high-safety parts common in the automotive and medical equipment industries. However, the two-shot molding process can be tough to master since it requires a high degree of precision, technical know-how, and attention to detail.
Two-shot molding allows for the seamless melding of two colors or resins. The materials are added to separate units and injected through independent nozzles, but into one plastic molding machine. The resins then form a bond in the process (rather than requiring additional adhesives), after which the completed part is cooled and removed.
Think of it this way…
Let’s pretend you want to draw two red and black lines side-by-side. First, you remove the cap of the red pen, draw your straightest line, and then put the cap back on. Then, you’ll remove the cap from the black pen, draw a line right next to the red, and once again put the cap back on. With two-shot molding, the red pen and black pen are coloring at nearly the same time, without the need for removing, changing and adjusting parts. This results in a design that’s more efficient and accurate.
Aside from improved product quality and time savings, other advantages include cost savings and less waste from assembly line processes and defects. Because two-shot is often used for complex multi-colored products, the overall savings from this type of efficient process can be significant, especially for high-volume printing projects.
Two-shot molding is also used to help meet specific safety and strength requirements for manufacturers. With the use of one operation, there are fewer processes involved and therefore fewer occasions for defects, contaminations, weaknesses or damage.
In summary, advantages of two-shot molding include:
At Sanwa, many of the two-shot molding parts we create are produced for the automotive or medical/dental industries. Parts include center consoles, device displays, dashboards, buttons, control panels, toy parts and more.
The combination of materials can include a clear resin (for a display window, as an example), as well as a color resin to frame the window and match the surrounding design. This makes two-shot molding ideal for luxury car interiors that require seamless and exact-match applications.
In reality, many plastic items you’ve held or viewed were produced using a two-shot process -- you just may not have known it. While we specialize in the auto and medical fields, two-shot can also be used for food containers, electronic products, toiletries, household tools and more.
While two-shot molding may be simple to understand, the reality is that the process can be challenging to master. Manufacturers must approach two-shot molding projects with a high level of expertise, creativity and competence. When combining colors and materials in this precise manner, small flaws can lead to costly waste and production delays. Therefore, choosing a quality two-shot molding manufacturer requires doing some homework and asking questions related to their experience, capabilities and references.
If you would like to talk to our team about two-shot molding possibilities, we recommend giving us a call early in your design and planning phase. We can help with troubleshooting, lending guidance and answering any of your lingering questions about the advantages of two-shot molding.