Two shot molding involves the injection of two different plastic resins into one injection mold, allowing for multi-material and multi-colored products without any additional machining processes. This process offers engineers a great deal of flexibility when designing new product shapes and functions. It allows you to add features and functionality that are often impossible to manufacture using other techniques. Having multiple materials injected together also eliminates the need for assembly, saving valuable production time and eliminating costly mistakes caused by weldment or joining components.
2 shot injection molding works by first injecting the first material into a cavity in the injection mold(s). Once this has set, a separate injection unit then fires a second shot of a different material over the first, which has already been molded. This process is sometimes referred to as overmolding, but it is actually an injection molding technique.
The process is not as complicated as it sounds, and there are a number of options for this type of molding. Some variations include rotary platen and movable core. The rotary option requires a rotary platen on the injection molding machine to rotate and then insert the second shot. The movable core version does not require a rotary platen and instead uses a series of internal slides to adjust the position of the injection mold after each shot is molded.
Both types of injection molding have advantages, but it’s important for product makers to do their due diligence and carefully evaluate all critical considerations against their manufacturing goals. The chemistry of the individual compounds plays an important role in how well they bond to one another and whether they can form a solid molecular adhesion, which is required for successful two-shot injection molding. The most effective approach is to conduct an adhesion test before beginning manufacturing.
If you choose to use 2 shot injection molding for your next project, you should make sure to partner with a trusted supplier with proven expertise in this type of manufacturing. This is particularly true when working with very high-volume production runs. A capable supplier will be able to produce parts at a very high speed, while still maintaining quality and preventing costly defects such as flash, flow lines, and short shots.
This injection molding technique is a great choice for many types of plastic products, such as toys and storage containers. This technique allows for a range of color combinations and textures to be used, as well as hard-wearing base areas combined with softer seal surfaces. This provides greater product durability and a better customer experience. For example, medical equipment such as bone saws can be produced with a rigid base plastic that is combined with rubber grips, improving hygiene and making the tool easier to handle. 2 shot molding