A Mild Steel Gluing Tip!!
Your guide to obtaining the optimum strength!!
For any given glue system, the complete preparation of the materials being bonded is the single most important factor that will determine the longevity of the bond. Various surface preparation methods have been adopted depending on the materials being bonded and the requirements for the glued parts. Indeed here at our laboratories, we have developed a range of surface primers for use with specific materials. We have also developed surface modification processes, which allow for the optimum bonding of a range or plastics, composites and metals.
One metal, such as mild steel, is very commonly glued. We have a range of glues that are quite suitable for gluing mild steel and we have a very wide range of customers, for which the strength of a glued mild steel joint, forms the basis of what is being manufactured.
What are the best ways to prepare mild steel before gluing? Well there are several methods……….! Degreasing is probably the easiest form of surface preparation, followed by hand tool abrasion and power tool abrasion. Solvent wiping, followed by blast cleaning and a second solvent wiping, is probably the most commonly used surface preparation technique which we advise. This process is the main surface preparation method for many of our customers who glue rubber to mild steel.
There are several Standards for blast cleaning mild steel, the most commonly used of which is Swedish Standard SIS 05 59 00-1967. Within this Standard, there are four grades of cleaning, SA-1, SA-2, SA-2.5 and finally SA-3.
SA-1: Light blast cleaning, which removes mill scale and rust.
SA-2. The commonly used commercial blasting technique
SA-2.5. The most commonly used industrial blasting technique, this process cleans the metal to a dull lustre, quite suitable for all but the most demanding gluing applications.
SA-3. This is the most thorough process. The metal is cleaned so as to take on an ‘as new’ finish.
So how important is blast cleaning your mild steel? Well, depending on your application, we do often suggest this method. Adding surface roughness to a metal, greatly assists in creating what we call an ‘anchor pattern’. Surface roughness creates a very glue receptive surface, plus increases surface area. But be careful, after blast cleaning your mild steel, glue it within the hour. The freshly blasted surface is very reactive and starts to tarnish almost as soon as blasting has finished.
For gluing say natural rubber or nitrile rubber to mild steel, is there an ideal anchor pattern? Yes there is, using say an 80 mesh sand, we would expect to achieve a roughness height profile of about 36 microns.
But what if your are looking for the absolute strongest bonds? Well, we recommend iron shot of about mesh size 14. Using this, you can expect a roughness height profile of approximately 90 microns. With the right glue and gluing process, don’t expect things to fall apart, it just will not happen!!
As Ireland’s premier adhesive manufacturer and distributor, we offer a complete range of industrial adhesives, accompanied by the best adhesive advice available anywhere. Our laboratories are always available to help you. Let us create the right bond for you.