The Benefits and Challenges of 2 Shot Molding
Two shot molding, also known as double injection or 2K molding, is an innovative manufacturing process that allows two different types of plastic to be injected into one tool set in a single machine cycle. This type of multi-material injection molding requires a great deal of engineering and testing to ensure that the parts will function properly when molded together. It is also important to understand how the chemistry of the two materials interacts in order to avoid any issues with adhesion.
In addition to being a more efficient production process, this type of injection molding can also help reduce the cost of your product. It is less expensive than insert overmolding, and it eliminates the need for secondary assembly as the molded product can be used as is. It also provides a much more precise final product, especially if the product is designed with careful consideration of the thermal effects involved.
While the process of 2 shot molding has many benefits, it can also be challenging to implement and is often considered more complicated than the standard injection molding processes. This is mainly because the injection molding machinery needs to be programmed to execute two separate cycles, and it can take longer for the molds to be opened and closed between each injection. Additionally, the injection process must be able to handle a variety of different plastics with varying viscosities.
Another significant issue that must be addressed when producing 2 shot molded products is the temperature differences between the materials. If the injection molding process uses two different plastics that have differing melt temperatures, it can cause the substrate to distort as the second material is injected. This can be avoided by using materials with similar thermal properties or incorporating supports and ribs into the design of the part.
Due to the challenges associated with 2 shot molding, it is crucial that you work with a highly capable manufacturer when designing your product. An experienced manufacturing team will be able to provide guidance and advice throughout the development and prototyping stages of your project. They will be able to help you decide whether 2 shot injection molding is the best option for your product and help you with the development of high-quality molds that are able to produce accurate and consistent results.
The most common form of 2 shot molding involves a rotary platen that has a stationary half and a movable half. The movable half has the ejector cavities and the second runner system, while the stationary half has a core and cover cavity for each of the shots. Once the first cavity is molded, the movable part moves out of the way and the second shot is injected.
Aside from the added benefits of reducing costs and providing more precise components, two-shot injection molding also offers the ability to create ergonomically designed products. This can be done by combining the structural plastic of the product with a soft and rubbery material that is more suited for human contact. This is an ideal solution for buttons and switches, handles and grips, and caps for containers.
