Mild steel, also known as carbon steel is a common material used in automotive and machine components. There are several options to bond mild steel and adhesives can be selected based on the environmental, temperature, and chemical resistance needed. The key to a good bond on mild steel is proper surface preparation.
1. Remove large particles of rust and debris with a wire brush or wire wool.
2. Often steel is painted or powder coated. Bond strength will be limited to the strength of adhesion of the paint or coating unless you remove this layer.
3. Degrease with acetone, isopropanol or Permabond Cleaner A. Do not use white spirit or meths as this can leave a residue. It is important to carry out this step before abrading. Otherwise you will ingrain dirt or oily contaminants into the surface.
4. Abrade by one of the following methods
-Wet and dry grit paper (carborundum paper) 320 grade recommended.
-Red Scotchbrite pad
-Alternatively, a grit blaster can be used (make sure to use fresh, uncontaminated sharp grit).
5. Degrease again to remove any contamination or loose particles.
6. Bond as soon as possible otherwise the surface will re-oxidize.
Anaerobic adhesives – threadlockers, thread sealants, form in place gaskets and retaining compounds all work well on mild steel.
Cyanoacrylate adhesives – all grades bond stainless steel, but special grades for metals will have increased adhesion. Permabond 910 is the original pure methyl cyanoacrylate which was developed for bonding metals. Although cyanoacrylates have very high strength applications involving mild steel often have environmental requirements that are best met with a structural adhesive.
Structural adhesives like one component heat cure epoxies, two component epoxies, and structural acrylics bond mild steel and have good chemical and heat resistance.
UV curable adhesives bond well to stainless steel providing the second substrate permits UV light to pass through. Metal to glass grades include; UV610, UV620, UV625, UV670, and UV7141.
