Most of our everyday items consist of more than one material. Take a pair of scissors, for example. They typically have a plastic handle along with metal blades. It sounds simple, but engineers need to think about what method they want to use to adhere different materials together when making a product, such as scissors. One of these methods is called insert molding.
We will be discussing insert molding and how it is beneficial for physical properties, electrical applications, and aesthetics.
What is Insert Molding?
Insert molding is a powerful tool used to bolster the form and function of plastic injection molded parts. Insert molding refers to incorporating other parts, particularly metal parts, directly into the injection-molded product. For instance, say we have metal inserts that we need to bond to plastic; you would place the metal inserts into the mold before injecting the plastic. The inserts will be subsequently surrounded by the plastic during the injection process, leaving the insert bonded firmly to the material after cooling and curing.
Insert Molding for Physical Properties
The insert molding process typically involves the incorporation of another material into a plastic component. This incorporation is to provide a localized hard point for locating or fastening components.
Inserts are usually for providing a wear-resistant area for moving components. One of the most common forms of insert molding is the incorporation of brass-threaded inserts, as seen below.
These inserts provide a stronger connection point than threads formed directly into the plastic. Brass inserts are also much more wear-resistant than plastic, allowing components to assemble and disassemble multiple times without significant wear.
Conversely, knobs with threaded shafts are also a common occurrence in insert molding. If made of plastic, the long threaded shaft can be susceptible to wear and breakage.
Some other applications for insert molding include screws, spindles, hard contact point bearings, bushings, and dowel pins.
Insert Molding in Electrical Applications
The use of insert molding is common in the world of consumer electronics. The ability to fix electrical components within an insulator has proven to be invaluable to the industry. The electronics industry utilized insert molding for several different reasons:
- Protection from the environment — Electronic components or entire circuit boards can be placed in the injection mold and embedded within the material. This can be done to waterproof said electronics or generally protect them from the environment. Encapsulation can also be used to help prevent shock and vibration damage to electronics. Insert molding can also create the functional strain reliefs found on most cables (To learn about strain reliefs more in-depth, give our article a read).
- Ease of assembly — Electrical contacts are set as inserts in the injection molding process. This eliminates the need for tight tolerance press fits or costly assembly.
- Less bulky — The elimination of screws and other fasteners allows for a less bulky design that can perform better than alternative assembly techniques.
Insert Molding for Aesthetics
In-mold decorating and in-mold labeling is when a thin firm with printed decorations or labels is placed in the mold before injection. During the injection process, the firm and the material fuse together to form a rugged but high-quality, high definition finish on the finished part.
In-mold decoration and labels have several advantages over other processes, such as conventional labeling methods.
In-mold labeling can provide very tough, wear-resistant labeling used on keypads and other high wear surfaces.
This labeling technique is also waterproof and chemically resistant, which makes it ideal for specific products.
Labeling ice cream and other refrigerated containers tubs exposed to moisture during storage and transport are among the most common uses for this labeling technique. It removes the need to include paper-based labels or adhesives to the plastic.
Conclusion
Insert molding is an excellent technique for a plethora of reasons. It is beneficial for the physical properties of objects, electrical applications, and aesthetics.
At Jaycon, we have worked with a multitude of projects requiring insert molding. If you are unsure whether your project is suitable for or requires insert molding, get in touch with us. We would love to guide you through the manufacturing process and assist you throughout the design phase to ensure your product is optimal for manufacturing.
