What is overmolding?
Overmolding is the process of using a foam application to mold over a tube, pipe, or piece of metal. The process has the capability to change the aesthetics and performance of a piece of equipment. While its primary application is to provide a clean, textured finish to an application, overmolding can also be used to address heat and noise concerns that may come up. The versatility and range of applications make the overmolding process a vital part of the manufacturing process. Though it is a relatively common process (for example, you may see overmolding on the handles of a pair of pliers), overmolding has many applications that are more complex and demanding.
How the overmolding process works
The overmolding process generally begins with a collaborative discussion between the supplier and the customer on the exact needs of the application. This may involve 3D CAD drawings to illustrate what the overmolding will look like and how it will physically work in the given space of the application. Initial discussions will also cover any thermal or acoustical parameters that are necessary. Once the specifics of the design have been agreed upon, the overmolding manufacturer will formulate a prototype mold, usually of stereolithography (SLA), selective laser sintering (SLS), or Aluminum, and the customer will send the manufacturer the component that is to be molded.
When everything is ready for the actual molding, the manufacturer suspends the component to be molded within the mold tool before the foam product is injected into the tool. The foam product then encapsulates the component or portion of the component if a complete overmold is not necessary. To return to the example of the household pliers, only the handles that are to be overmolded would be encapsulated by the molding tool. After demolding is complete, there is generally some trimming to be done to improve the aesthetic look of the component.
How overmolding can help your application
When considering overmolding for your application, it’s important to understand how that piece of equipment or appliance will be used. Overmolding can be a great way to address thermal and noise concerns in addition to providing a nice finished look. Overmolding is an extremely expedient way to arrive at a highly aesthetic finished part that usually requires thermal or acoustical consideration.
Though, of course, dependent on the specific materials used, overmolding generally provides a durable and cost effective solution. Not only do you get a more aesthetically-pleasing application, but you get one that will last a while without breaking the bank. With overmolding, the use of a foam application allows for a given treatment to have a very complex design. Overmolding even allows for varying thicknesses across different parts of a treatment. For instance, on one side of a treatment you could have a one-inch thick overmolding, while on the other side, only half an inch.
Applications where overmolding can be a solution
One place overmolding is particularly utilized is in the diesel engine industry. Given the complex and crowded nature of an engine, overmolding is an ideal solution. Here, the hoses, pipes, and valve covers can all be covered to create a bond surrounding the part enabling better heat management for those particular components and improved noise control for the engine as a whole. Similarly, medical appliances utilize overmolding when there are acoustical and thermal concerns.
Overmolding is a popular solution for covering armrests within the cabs of trucks, particularly those used by the agricultural industry. These cabs often lack comfort for their drivers, namely bare metal armrests. A simple foam application to the metal armrest creates a significantly more comfortable environment for the driver as well as giving a far more aesthetic, finished look to the cabin.
Though not particularly common, overmolding can also be used to provide security for an application. For instance, the motherboard of an electronic device might be overmolded to protect it and hold it in place. Branding considerations can also be addressed with overmolding provided certain materials are used. A self-skinning urethane, for example, can be printed on to feature a company logo or other branding message.
The range of applications and uses overmolding gives manufacturers makes it a worthwhile consideration in a multitude of manufacturing projects, whether it's simply improving the aesthetics of your environment, a practical measure to cover a metal surface, or as a solution to address thermal or acoustical concerns.