Whether you're building a model, working on a craft project or doing repairs around the house, bonding two different types of material, such as metal and plastic, can be a challenge. In order to make sure you create the strongest possible bond, you'll need to choose the right sort of glue for your bond.
Different types of metal and different types of plastic have different properties; sticking steel to flexible plastic and sticking tin to a rigid plastic may be very different experiences. Before attempting to glue the items you want to connect, try the glue on a smaller area and observe the drying process. Many adhesives can have harmful fumes, so be sure to work outdoors or in a well-ventilated area.
Cyanoacrylate glue, often called superglue, can create a strong bond between metal and plastic. This type of glue works best on rough or porous surfaces, so using sandpaper or a file to abrade both surfaces before gluing can help to make the bond stronger. Plastics that bend easily will generally not respond well to cyanoacrylate; the more rigid the plastic, the better. If the plastic is shiny with mold release oil, wash it first with warm water and dish soap. Cyanoacrylate can cause clouding on transparent plastics.
Two-part epoxies provide a strong bond between a wide range of different materials. When mixed, the two parts of the epoxy should be applied quickly and then allowed to cure. Because the drying process can be slow, you may wish to clamp the two surfaces together to promote rapid bonding. Like cyanocrylate, epoxy can have powerful fumes and should be used in a well-ventilated area.
White PVA glue will not promote a strong bond between metal and plastic. Polystyrene cement, which is highly effective at bonding plastic surfaces, similarly will not create a working bond. Hot-melt glue can bond metal to plastic in sufficient quantities, but it can produce unsightly excess glue. Because metal-to-plastic bonds can vary greatly, each different combination calls for a different type of adhesive, but cyanoacrylate and epoxy are the best candidates.