How to glue metal to plastic: The best glue for a permanent bond 

When you need to bond metal to plastic, you have several choices of adhesives. This article will help you decide which one is best based on several factors.

First, you need to make sure that the glue you choose will bond to the type of metal and plastic involved. For example, stainless steel and some types of plastic, such as polyethylene (PE) and polypropylene (PP), are resistant to many glues.

You’ll also need to ensure the adhesive will hold up under the conditions the object will be subjected to. For example, outdoor objects will need to be resistant to moisture, temperature extremes, and UV light. Most indoor glues will not hold up long to these stresses.

Another factor that can break a rigid bond is constant vibration. Use a flexible adhesive to bond metal to plastic if the repair will be subjected to engine vibration (such as automotive parts) or similar types of stress.

Finally, epoxy is the best choice if your parts are not close fitting or perhaps partially missing. Epoxy is rigid enough to span gaps and fill in surface imperfections.

Let’s look at how to use three of the most common adhesives for bonding metal to plastic. Then we’ll make some specific product suggestions that may help you choose the best glue for your project.

1. Set up and gather materials. Set up your workspace in a well-ventilated area with adequate lighting. You’ll need glue, sandpaper, a razor blade, and water or acetone for clean-up.

2. Prepare the surfaces. Rough up smooth or shiny surfaces with sandpaper to improve adhesion. Then wipe away any dust. The surfaces must be clean and dry for best results. 

3. Pre-fit the parts to be bonded to ensure a tight fit.

4. Apply a small amount of super glue to one of the surfaces to be bonded. Stick the metal to the plastic, and hold the parts in place until a bond begins to form.

5. Clean-up by wiping away excess adhesive. (Larger quantities of uncured glue can be removed by applying water to it, allowing it to cure, and then scraping it away.)

6. Allow the item to fully cure for 24 hours before use.

7. Cut away cured adhesive using a razor blade, or soften it with boiling water or acetone. Test the surface with a small amount of acetone before use to ensure it will not stain or damage the product.

Using a plastic bonder is very much the same as above with the addition of an activator. Apply activator to both surfaces and allow it to dry for 60 seconds. Then apply the adhesive to one surface and proceed as usual.

Epoxy is a two-part adhesive consisting of resin and a hardener. Mix the two in equal parts on a disposable surface for about a minute, then apply the adhesive as you would with super glue. Most epoxies come in dual-syringe dispensers to make measuring and mixing quick and easy.

For many minor repairs, we recommend Loctite Super Glue Control. It dries transparent in just seconds and bonds to metal, plastic, leather, wood, and most other common materials.

If you are working with polyethylene, polypropylene, or other hard-to-bond-to plastic, the best choice is Loctite Super Glue All Plastics. This dual-action adhesive will bond to virtually all plastics as well as metal, porcelain, wood, and paper.

When an epoxy is called for, try Loctite Epoxy Gel. It forms a high-strength, rigid bond in just 6 minutes and will bond to metal, most plastics, glass, concrete, and more. It won’t shrink and can be tinted to match surrounding materials.