Insert-molding enables a single co-joined part to contain multiple materials. Previously molded or machined parts, metal or plastic, are inserted into the mold cavity so that the injected resin, either thermoplastic or elastomer, solidifies around them.
Insert-molding enables In-Mould Labelling, a popular design technique which gives designers the facility to embed labels, logos, artwork etc. into a finished product or part. We see this commonly used in the manufacture of phone cases, where pre-printed artwork is inserted into the mold cavity so that, once injected, the artwork is physically sealed inside the back/sides of the case, creating a single unified piece. As opposed to the artwork being printed or stuck on the case after it is molded.
Some molds allow pre-molded parts to have another layer form around them in a process known as over-molding, thereby producing double layer, one-piece items. This process is further refined with double-injection or multi-shot molds where a two-layer part or product is created within one machine either as two shots, one after the other, or co-molded in one cycle. Double-injection molding machines allow for relatively complex two-layer parts or products to be rapidly produced. These final unified pieces can clearly show two distinct materials and colors, or form a more subtly integrated aesthetic.
Understand better what you can do on your next project by reading our Insert & Over Molding Guidelines.