Metal screws come in a wide variety of sizes and are used to hold together wood, plastic and numerous other materials. Sometimes if you use the wrong size screwdriver to remove a screw, it strips the screw head. A stripped head does not have grooves so the screwdriver can no longer turn it. Removing stripped metal screws must be done with a drill and involves disintegrating the screw.
Insert a 1/8-inch drill bit into an electric drill.
Place the tip of the drill bit in the very centre of the stripped metal screw. Pull the trigger on the drill to create a 1/8-inch-deep hole in the centre of the screw head.
Remove the 1/8-inch drill bit and replace it with a 1/4-inch drill bit. Repeat the process to drill into the screw head again. At this point the actual head of the screw will come off exposing a short piece of the screw shaft.
Place a pair of pliers around the exposed upper portion of the shaft and grip it very tightly. Turn the pliers counterclockwise to remove the screw from the object.
You can also place a rubber band over the stripped screw head and then insert the screwdriver tip on top of it. If the head is not completely stripped, the rubber band often gives the screwdriver enough traction to turn and remove the screw.