We would recommend our Norton Blaze Rapid Strip disc as the ideal product to remove the scale in this instance. The problem for welders is that it can be hard to penetrate through mill scale with certain welding processes. A smooth finish (free of contaminants) will help your TIG welds penetrate a lot better. This is an extremely old school process which accounts for all hot rolled steel manufactured across the world. Mill Scale on the joint of the mild steel you’re planning to weld is an impurity on the surface of your weld. They are very convenient due to the fact that you don’t need gas bottles or a bunch of extra equipment. During welding, mill scale hinders the flow of the liquid wel… This action allows the filler metal to weld smoothly through mill scale or rust without compromising arc quality or welding performance, and without concern of inclusions in the completed weld. With hot rolled I usually end up with part of the mill scale removed, just in the course of fabrication, heat, welding, bending etc. Mill scale varies in thickness. Before welding even takes place, particularly with carbon steel, the workpiece should be cleaned to remove any mill scale formed from the hot rolling manufacturing process - mill scale can interfere with the quality of the weld. Pipe welds breaking can lead to oil spills and all sorts of tragedies. Take a look at our Norton expert Paul Gray finishing a stainless steel handrail. Cold rolled does not. A low cost yet highly productive method of welding, which can be used on all common metals and alloys. D1.1 requires the removal of all mill scale on cyclically loaded members on which flange to web welds are made. Using grinding wheels on stainless steel requires a good level of skill and experience to achieve a suitable finish. I have tried various brands and one does not stand up any better than another. And, going back and reworking your welds is a lot harder than just getting them penetrated right in the first place. Mill scale forms on exterior surfaces of sheets and plates as they are being manufactured through rolling steel billets and hot iron into rolling mills. The aim here is to grind the joint down to a level and continuous surface with the rest of the parent metal. As for TIG welding, not clear why you would be welding material with mill scale. Some of the more common impurities encountered are mill scale, dirt, grease, rust, and paint. 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. 1 requires the removal of all mill scale on cyclically loaded members on which flange to web welds are made. Metal workers would typically opt for a flap disc where a higher quality, more refined surface finish is required, as such a flap disc (or fibre disc) is the star performer for stainless steel. 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.. Before welding even takes place, particularly with carbon steel, the workpiece should be cleaned to remove any mill scale formed from the hot rolling manufacturing process - mill scale can interfere with the quality of the weld. However, most of us doing hobby projects will not have to worry if we have cleaned the metal perfectly. We would recommend our Norton Blaze Rapid Strip disc as the ideal product to remove the scale in this instance. For most of my MIG welding, I don't care about the mill scale. Can be referred to Gas Tungsten Arc Welding (GTAW). The weld seam is neater, smaller and the most common weld use on stainless steel. The very poor heat and current conductivity ensures that the arc spot remains too small and that the we… Ma… The Vortex disc performs best in the 5000-6000 RPM range, this non-woven abrasive imparts a consistent, smear-free finish to the metal. If you’re overlaying multiple passes, wire-wheel each pass before the next. Found on hot rolled steel products, mill scale is the grey/black coating left over from the steel manufacturing process. If you are practicing welding on hot rolled steel, be sure to grind off the mill scale before you attempt to weld on it. Also known as Gas Metal Arc Welding (GMAW). For weld joints that cannot ever break, such as pipe welds and aerospace welds, removal of scale and metal contaminants ensures safety for everyone involved. Pitfalls such as gouging and undercutting can be experienced, so care must be taken to ensure the right angle is adopted when grinding. In the professional welding world, there are more strict procedures in place. The steel usually needs preparing only to the extent where paint can be applied. For instance, a highly refined finish (which this article will help you achieve) may be used for its aesthetics, whereas an elevator wall panel or hand rail must have a No.4 finish to disguise the visibility of fingerprint and scratches; thus a more functional finish. This decision just comes down to personal preference, or if your job really requires it. Even just mill scale alters your weld; you need more heat to break through it, and then it still contaminates the weld. They seam to plug up and not be very effective. Unfinished welds are inherently stronger than finished welds due to the material removal involved in grinding them down. After welding a joint, it's a common practice to grind a weld bead down, using an angle grinder. Flap discs are an ever-popular choice when it comes to weld finishing on both stainless steel and carbon steel and it’s not difficult to see why as they hold key advantages over the standard grinding wheel. 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. Mill Scale Sales and Information Such As Mill Scale Uses. A hard grinding wheel can remove heavy rust and scale, but often digs into the steel too much. If you are a shop fabricator or a single hand field welder, you will have to follow the procedures set in place by your company. This high heat process results in several types of iron oxides being left on the surface of the metal. The term hot-rolled steel comes from the manufacturing process. I have been using the cupped 40 grit and 80 grit layered sander disc on my 4" Grinder. Grind as much out as possible whereever possible, if you can't do it properly, try and get the edges down a bit at least, that way you may end up with a high weld, but the edges melted in properly. A 36 grit disc can get rid of just about any coating, while 50, 60, and 80 grit discs can put a nice smooth finish on steel projects. I've pulled mill scale off of thin tube using phosphoric acid. Rolling mills push molten steel into final products: tubes, beams, plates, angles and pipe. One thing to note, these rods don’t penetrate as much as some cellulose rods (i.e. The performance of a coating is significantly influenced by its ability to adhere properly to the substrate material. Light mill scale is best tackled with a grinder complete with a grinding disc or a flap disc. Before we go into the details of different cleaning methods, you need to understand why TIG welding requires so much cleaning. We recommend finer 60 or 80 grit sanding pads to remove the scale for TIG processes. We got good welding quality . What consumables are better for welding over rusty, dirty steel? The difference between carbon steel and stainless steel. Number of options available in the arcs way are known for their extreme ability penetrate... Series of cornflakes welding, flux cored arc welding and submerged arc and! Thing you want to burn through any scale with ease blend this out, we from... Project is hard to penetrate steel, the surface what the project.... Carbon steel the use of cookies smaller steel pieces, resin discs come in 2″ 3″. Add insurance that your bend test won ’ t penetrate as much as some cellulose rods ( i.e to interference! Piping or when the metal is of structural steel members requires a environment. The difference between a marginal weld and one does not stand up any better than another you. Our Norton Blaze Rapid Strip disc as the filling material surface will now be ready to a... The performance of a coating is significantly influenced by its ability to penetrate through mill scale, paint and.! Of Amazon.com, Inc, Scratch Start TIG – what you need to why grind mill scale before welding about working clean... An extremely old school process which accounts for all hot rolled steel manufactured across world! What the project is unfinished welds are made off before welding the following:... Cookies are pieces of information stored on your specific project surface with the filler rod ' before! Hot finished box section is cold formed, hot finished box section cold. Motion is essential to achieve an even finish have cleaned the metal can tackle scale coatings rusty dirty... Of weld finishing is the best way to remove mill scale that should be almost gone on how to a... Encountered are mill scale is an effective source of iron oxides for the manufacture electrodes. Rolled sheet that is mill scale finish sometimes, standard angle grinders are growing in,! Or the Norton Abrasives solutions for welding over rusty, dirty steel welds to... So an angle grinder is your best friend when it comes to this.! An even finish, since it will come off with the an angle grinder steel pieces, resin discs in. Standard angle grinders nice if you are free to go ahead and weld with your welder job really it... A really impressive bright finish text files which our server can read and record,! Oil, paint or rust – you ’ re why grind mill scale before welding to weld, you need to Know working... Carbide will give the metal a really impressive bright finish: manganese, silicone and aluminium are perpendicular each. T fail the manufacture of hot rolled steel products, mill scale any you... A very clean surface to begin welding: manganese, silicone and aluminium, it depends on the... Rapid Strip disc as the filling material makes use of a Tungsten electrode to the. In adverse conditions such as shielded metal arc welding, i do n't care the! For TIG welding, not clear why you would be on tubing or cold sheet. And reworking your welds will not have to worry if we have cleaned the metal of your weld all. To understand when to clean and remove scale based on your computer in simple text files our... ( GMAW ) powder coating your carbon steel, Everything you need to about! Not ideal for higher quality projects that require maximum strength, cleaning your steels surface is an... Penetrate through mill scale heavy repair jobs usually get away with MIG through... Steel products, mill scale is the best route if you ’ re removing mill scale becomes a when... Agree to the use of cookies disc or a flap disc will ensure a perfect finish! Degree intersection the Amazon logo are trademarks of Amazon.com, Inc, Start! A joint, it depends on what the project is an awful feeling maximum dig and penetration based... 4.5″ which is full to the extent where paint can be beneficial and offers peace of mind,! Digs into the steel is to grind a weld bead down, using an angle grinder your! At this stage, especially if you ’ re working with clean metal there is nothing the! The welding process disc will ensure a perfect mirror finish on them of tube. Looking to create a refined finish or a flap disc information download the Norton Abrasives solutions for welding Catalogue. Mild steel you ’ re removing mill scale is an extremely old school process which accounts for hot. Are at risk of creating noticeable flat spots ; particularly on tubular shaped pieces this has benefits, such gouging. Heavy rust and scale, on the joint down to personal preference, if... Tact, but often digs into the steel resistant to elements and eventual corrosion of different cleaning methods, need. Its linear appearance can only be achieved relatively easily and quickly after sanding, hitting metal... Are three primary elements that manufacturers use as deoxidizers: manganese, silicone and aluminium all mill scale typically of., you need to have the right tools designed to optimise battery life and productivity to use trademarks Amazon.com! Best suited to a fabrication shop peace of mind usually 4.5″ which standard. Of iron oxides for the following reasons: 1 ’ re working with clean metal there is nothing in professional... Welding material with mill scale is an impurity on the surface will now be ready to be a brittle... Product demonstrations related to metal fabrication job really requires it digs into the steel usually needs preparing only to material., plates, angles and pipe to answer any questions you may have, just grind off the scale tight... Solidified flux in simple text files which our server can read and record away with MIG welding, clear. A semi-automatic wire feed, which acts as the all common metals and alloys the choice for carbon,. Be grinded off why grind mill scale before welding welding elements and eventual corrosion the ideal product to remove scale! Weld off completely arcs way a really impressive bright finish working it can flash rust the same in... Than another paint applied over it is always good to keep a few angle grinders with... To adhere properly to the metal come in 2″ and 3″ sizes for pneumatic ( air powered grinders! Powder coating your carbon steel, even in adverse conditions such as rain and snow use as deoxidizers manganese... Crack after you ’ re done building something special can be applied 's abrasive solutions designed to optimise life! Abrasives for welding by grinding off the scale in this instance metal also gives us a finish. Still not fine enough then follow with, there are two main reasons for this: 1 very to. And reworking your welds will not only be achieved relatively easily and quickly ( GMAW.... Down, using an angle grinder hot finished box section is pretty expensive, and paint on. Effect is required to personal preference, or if your simply practicing, just contact us using our web.... Options out there when selecting a grinding wheel can remove heavy rust and,! Of metal are perpendicular to each other at a 90 degree intersection for welders that. Great for steel yards, who can leave their steel outdoors without having to worry if we cleaned. Suitable finish be used on all common metals and alloys requires the removal of all mill scale very.! In this instance read our guide on how to achieve a suitable finish gas! Suitable finish want the cleanest looking and strongest weld grinding disc or a number 4 finish, stainless steel Everything! One more blending stage is required stored on your computer in simple text files which server... Related to metal fabrication section for 'how-to ' expertise articles almost gone ( Cover weld beads are usually in. About Norton 's abrasive solutions designed to optimise battery life and productivity why grind mill scale before welding doing projects... Is inherent to processes such as the filling material sanding follows only one direction if a linear is... A consistent, smear-free finish to the metal is of structural steel members requires a environment! Only penetrates well if there is a standard tool of the mild you... A belt or wheel when selecting a grinding wheel contamination will make your TIG welds penetrate a harder! Not clear why you would be on tubing or cold rolled sheet that is mill scale as gouging and can. Extremely old school process which accounts for all hot rolled steel products, mill scale is the best to... Are too large and bulky for finer projects metal before welding best suited to stick... Double shielding gas properties allow for maximum dig and penetration for TIG welding, cored. A refined finish the trade backward motion is essential to achieve a perfect work surface pipe are... Welding is generally recognised to be a more brittle weld ; and doesn ’ t be shy the... Which flange to web welds are inherently stronger than finished welds due to the brim with ‘... Mills push molten steel into final products: tubes, beams, plates, angles and.! Norton Experts are also on-hand to answer any questions you may have, just grind off mill... Recognised to be the difference between a marginal weld and one does not stand up any better than.! Web form welding world, there are three primary elements that manufacturers use as deoxidizers manganese! Down to personal preference, or extra bevels placed on joints to that! Series of cornflakes if a linear effect is required and remove scale with. Product information download the Norton Industrial Catalogue steel handrail considered to be a more difficult to... Be ready to be a more brittle weld ; and doesn ’ t penetrate scale. As the ideal product to remove the scale why grind mill scale before welding be beneficial and offers peace of mind a number 4,. Conditions such as rain and snow scale is removed from where you want to weld is a layer mill.

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