Removing stuck screws in any surface requires specific tools and the right touch. Extracting a screw stuck in metal can be even more challenging. When a metal screw is anchored into a piece of metal, such as aluminium, a process known as "seizing" can occur. Due to pressure applied by the screw and the heat created by screwing it in, the metal can bond together unless an anti-seize preventive wax is applied to the threads. Brute force should not be used to remove the screw. Fortunately, there are a number of readily available products designed to gently remove a stuck screw.
Clean the head of the screw with steel wool or an emery cloth. Be sure to remove any dirt or oxidation that may interfere with inserting the screwdriver or that may be bonding the screw to the aluminium.
According to Classic Car Magazine, the first step in removing stubborn hardware is to lubricate the threads. Liberally spray the screw with a penetrating fluid, attempting to introduce the fluid down into the screw threads. The best penetrating fluids are designed for professional automotive use, but common household anti-corrosion sprays can be used with success. Let the spray sit for a minute or two.
Insert the screwdriver and gently turn it counterclockwise to loosen the screw. Use as little force as possible. If the screw doesn't budge, do not force it. Spray additional penetrating fluid in and around the screw and wait an additional 24 hours before any reattempts.
If the screw remains stuck, attempt to loosen the bond with a propane blowtorch. Heat the screw with the torch for a few seconds, then insert the screwdriver and gently try to remove the screw. For best results, avoid heating the surrounding metal as much as possible.
As a last resort, a stubborn screw may need to be drilled out. Using a titanium bit, carefully drill down into the screw until fully removed. Lubricate the contact point between the drill bit and the screw with motor oil to extend the life of the drill bit.
Never force a seized screw or bolt. Doing so can cause the screw to become permanently stuck. Never use a blowtorch around flammable materials.