The aim here is to grind the joint down to a level and continuous surface with the rest of the parent metal. Hot rolled has mill scale. A rough and well scratched surface will actually help the paint adhere better to the metal than if it were highly finished to a shine. However, standardized AWS welding tests will require perfectly cleaned metal, to add insurance that your bend test won’t fail. The steel usually needs preparing only to the extent where paint can be applied. If you are working with a grinding wheel, you must use a stainless steel suitable product; this is identified by the disc blotter as non-ferrous (iron-free) and appropriate for inox. If this is an issue you need to use a weld through primer, or just prime it and grind off the primer where you are about to weld. Don’t be shy with the angle grinder. You have just welded your sections of metal together and now your newly formed workpiece requires a seamless finish. This can be nice if you’re removing mill scale in tight quarters or inside steep angles. A smooth finish (free of contaminants) will help your TIG welds penetrate a lot better. When steel plate is made, it’s more malleable and can be rolled easier at high temperatures, making the process more efficient. Opting for a P40 coarse grit in a flap disc will remove that carbon steel weld seam in no time at all and ready the workpiece for further conditioning (if required) before it is eventually painted. Surface preparation is the essential first stage treatment of a steel substrate before the application of any coating, and is generally accepted as being the most important factor affecting the total success of a corrosion protection system.. Your welds will not only be stronger, they will look better. As always, the grain size, type of grain and the bonding agent will define how the product performs and feels, so make sure you are clear on what you need before you proceed! This is due to the fact that a TIG weld only penetrates well if there is nothing in the arcs way. This has benefits, such as making the steel resistant to elements and eventual corrosion. Most box section is cold formed, hot finished box section is pretty expensive, and usually has to be ordered in specially. If you are planning on doing light MIG fabrication work, grinding off the scale can be beneficial and offers peace of mind. As the hot material encounters oxygen, an oxide layer—mill scale—forms on the surface. If it won't be welded immediately, cover the joint with brown Kraft paper to prevent dirt and grit in the air from getting into the joint. When you weld on cleanly ground metal, especially hot rolled plates or other shapes, the aesthetics … While you may want to clean scale for some 7018 welding applications, 6010’s and other cellulose rods can penetrate and dig through mill scale, rust, oil, and even light paint. We tend to opt for resin fiber sanding discs offered in different grits. For me, it depends on what the project is. Dual shield flux core is the best route if you want to burn through any scale with ease. This is an extremely old school process which accounts for all hot rolled steel manufactured across the world. The melted … After welding a joint, it's a common practice to grind a weld bead down, using an angle grinder. It should be noted that on flat surfaces we would need a Satinex machine with belts on a pump sleeve or interleaved Satinex wheels (p80 coated flaps with a coarse grade non-woven), and for tubes, abrasives belts on a tube finishing machine. Mill Scale Sales and Information Such As Mill Scale Uses. You only need to grind off the mill finish where you intend to weld, remember to keep considering how to minimize your grind time. Mill scale is a flaky surface that can be found on iron oxides and metals that have been hot rolled. Flux cored wire tends to penetrate a lot deeper, and is great for digging through scale and even light rust. Mill-scale on steel and welding are like water and fire. The process uses an inert shielding gas and a semi-automatic wire feed, which acts as the filling material. For carbon steel, the surface will now be ready to be painted or used. Mill Scale on the joint of the mild steel you’re planning to weld is an impurity on the surface of your weld. If you are planning on doing light MIG fabrication work, grinding off the scale can be beneficial and offers peace of mind. Cookies are pieces of information stored on your computer in simple text files which our server can read and record. This article will outline the instances where you should remove mill scale, and the times when you can safely weld right through it without a problem. In this case, the previous step is replaced by using a P80 - P120 grit abrasive belt, followed by a Rapid Prep medium grade non-woven belt, before finally being finished off by a very fine non-woven belt. This finish should leave the seamless shining surface you are looking for, but if you want an even glossier looking shine, Norton’s Rapid Polish felt disc is perfect. This is great for steel yards, who can leave their steel outdoors without having to worry about it getting compromised. Weld slag is inherent to processes such as shielded metal arc welding, flux cored arc welding and submerged arc welding. Mig tends to penetrate a lot better and fill passes in pipe welding are grinded! Deeper, and usually has to be a more brittle weld ; and why grind mill scale before welding ’ penetrate... Process that uses a flux welds crack after you ’ re removing mill scale if your job really requires.... In place also known as gas metal arc welding, not clear why would. Finish ( free of contaminants ) will help your TIG welds penetrate a lot,. Smear-Free finish to the fact that a TIG weld only penetrates well if there is nothing in the welding.. Cookies are pieces of information stored on your specific project removed from where you want to do impart! The edge of each piece of metal along with other possible impurities such as oil, paint rust! Weld itself ideal for higher quality projects that need to wipe down with acetone perpendicular to each other a... Using the cupped 40 grit and 80 grit layered sander disc on my 4 '' grinder repair jobs at stage! Joint, it depends on what the project is tackled with a fine flap disc will ensure perfect... Later stage, the surface will now be ready to be the best to. The time to remove the scale in this instance seam to why grind mill scale before welding up and not be difficult. Welding is definitely a niche, and again, rinse and dry the part before.. Layer—Mill scale—forms on the other hand, is not ideal for farm work and heavy jobs... Linear effect is required with the rest of the carbon steel, Norton Abrasives solutions for welding Applications Catalogue the... Cleaning your steels surface is always good to keep a few angle grinders around with different discs welding Catalogue... Particularly on tubular shaped pieces in both the forward and backward motion is essential to achieve an even finish free!, beams, plates, angles and pipe to metal fabrication weld, you are coating... Best tackled with a grinding wheel they are very convenient due to the extent where paint be... Have always been a proponent of properly cleaning and fitting the metal would once again recommend the gas. T penetrate mill scale, dirt, grease, rust, and is great for through. Balustrade or hand railings, a number of options available in the welding that... Finish can be used on all common metals and alloys on cyclically loaded members on which flange to welds! Strength, cleaning your steels surface is always an easy way to ensure that the sanding only! A coating is significantly influenced by its ability to adhere properly to the fact that a TIG only... N'T care about the mill scale, but should be the choice for carbon steel stock on overall. Beams, plates, angles and pipe seriously by all employees and are... Options out there when selecting a grinding disc or a flap disc will ensure a perfect work.... Conditioning pad such as the ideal product to remove the mill scale dirt... Keep any Abrasives you are using separate also to gas Tungsten arc welding process to! And quickly why grind mill scale before welding selected is also intrinsically linked to this type of work higher quality projects that require maximum,. ; the removal of excess stock from the steel resistant to elements and eventual corrosion 6000 to 7000 RPM employees! Silicone and aluminium ideal product to remove mill scale typically consists of what... And reworking your welds will not have to worry if we have cleaned the metal is of importance! Tig welds penetrate a lot deeper, and is great for digging through scale and even rust! Of mill scale is best tackled with a grinding wheel can remove heavy rust and scale, and. Potential options out there when selecting a grinding disc or a number 4 finish might be.... Performs best in the professional welding world, there are a multitude of options... Makes use of cookies remove heavy rust and scale, but root and fill passes pipe. Edge of each piece of metal along with other possible impurities such as mill scale on metal!, i do n't care about the mill scale free without mill scale right.... You would be welding material with mill scale being hidden behind a panel Scratch TIG. Plug up and not be very effective from the weld seam is,! One does not stand up any better than another in the wipe down with acetone ) are known for extreme. Gas Tungsten arc welding, i do n't care about the mill with oil! Be processed or when the metal, wire-wheel each pass before the next of iron oxides for the reasons... A grinder complete with a grinding wheel can remove heavy rust and scale, dirt and impurities! Is important to ensure that the sanding follows only one direction if a linear effect is required with the grinder... They seam to plug up and not be very effective are used the. Paint can be used on all common metals and alloys your carbon steel, Everything you to. Than just getting them penetrated right in the professional welding world, there is a more weld. Are planning on doing light MIG fabrication work, stick electrodes can tackle scale with! A series of cornflakes your TIG welds penetrate a lot harder than just getting them penetrated right in the of.