Beyond Welding Beads: Innovative Uses Of Abrasives In Welding

WHAT ARE WELDING BEADS

A bead is the first type of joint that a beginner learns to make. A seam deposit that occurs in one stage during welding is called a weld bead. The most common type you deal with is dowels. Nevertheless, students can also combine dowels and dowels with different kinds of beads if they have the appropriate welding helmet.

THE FUNCTION OF WELDING BEADS 

One pass performed along a joint by the welding torch or electrode is referred to as a bead in the welding industry. The word can also refer to the welded metal deposit on the workpiece that raises or "beaded" the surface. Typically, bead formation requires multiple passes of the welding torch or electrode along the joint. Each time, a small amount of filler metal must be added.

The size and shape of the beads can be influenced by the kind of filler metal used, the welding method utilized, and the welder's experience. A well-formed bead usually has a set width and height and is uniformly dispersed.

WELDING ABRASIVES

Weld beads are finished with welding abrasives, which are power tool attachments. Accessories like brushes, deburring tools, cut-off wheels, and discs are used to remove excess weld material from a workpiece. A weld's appearance is finished, chopped, and blended during the grinding process. It is imperative to have the proper kind of welding abrasives and power tools.

1. ABRASIVES FOR WELD FINISHING

The weld bead might merely need to be cleaned to get rid of any contaminants or surface flaws, depending on how it will be used in the end. For example, all that's needed for a welding table or workbench are effective welds free of burrs that could cut your hand if left in place. In some circumstances, the weld could be reduced in size and mixed in with the surrounding base metal. 

Weld spatter, slag, surface oxidation or tarnish, discoloration, shallow surface fissures, burrs, stuck electrode tips, organic contaminants, undercuts, and excess weld material are examples of post-weld flaws and surface contamination.

To clean a weld, all you really need are wire brushes, semi-flexible discs, non-woven surface conditioning treatments, and flap wheels.

Larger flaws such as burrs, electrode tips, porosity, cracks, and excess weld material can be removed from welds using coated abrasive discs or belts, flap discs, and bonded abrasive depressed center wheels. Electrochemical tools such as weld cleaners or electro polishers are used to clean welds. Usually, they are employed to passivate and clean stainless steel welds.

Stress concentrations and a weaker weld joint might result from excessive reinforcing or too much weld material spreading past the weld face or root. Most welding regulations classify excessive reinforcement as a defect, which can be corrected by grinding off extra material.

Start with the finest grit size that offers a suitable metal removal rate to prevent removing too much material and weakening the welded connection in order to grind a weld bead down and remove welding surface flaws. In order to remove deep scratches and digs, coarser grits like 24 and 36 grits may need to be used in conjunction with extra abrasive finishing procedures.

Spot welding may be necessary to fill up a deep gouge caused by an aggressive grinding wheel or disc in the worst scenario. Products with 40 to 60 grit are usually a good place to start. Before switching to a 24 or 36-grit product, try ceramic or zirconia abrasives if a 40 to 60-grit aluminum oxide abrasive product grinds too slowly or wears out too rapidly.

Once the weld has been ground down, the leftover weld can be blended into the surrounding workpiece metal using abrasive materials ranging from 80 to 120 grit. When combined correctly, the welded product will have the appearance of one solid piece of metal with discrete weld locations. Additional smoothing or abrading with fine grit abrasives, such as a 120 to 180-grit product, can refine and further smooth the surface of the workpieces' mill surface finishes, which need to be matched.

2. ABRASIVES FOR FILLET OR WELD CORNERS AND TOUGH-TO-REACH WELDS

Since butt welds are created in the space between two surfaces, cleaning, deburring, smoothing, and grinding can easily access the welds. It is also simple to expose lap and edge welds to an abrasive disc or wheel. When two workpieces are perpendicular to one another, a corner, tee, or filet weld is created.

Grinding wheels, semi-flexible discs, and abrasive discs can be challenging to reach weld corners. On flat surfaces, these solutions work wonderfully for cleaning welds, smoothing out weld beads, and blending welds; however, they are less effective in corners, pockets, and difficult-to-reach places. A corner weld may be ground out by the edge of a depressed center grinding wheel, but over-grinding, undercutting, and digging into the sides are likely to happen. The best options are narrow-mounted flap wheels, narrow abrasive belts, cartridge rolls, cross pads, spiral bands, and various abrasives and equipment made specifically to abrade difficult-to-reach areas.

Flexible abrasives, such as nonwovens, mounted flap wheels, and cross pads, may adapt to the shape being ground, which makes it possible for them to smooth out weld corners.

A wire wheel attached to an angle grinder can also be used for simple weld cleanup tasks such as eliminating slag, spatter, and discoloration or oxidation.

To clean or finish a welded corner, a slower, manual method involving hand files, abrasive sheets, shop rolls, and nonwoven hand pads may be adequate for small works with limited space for corner welds. Although this causes processes to go more slowly, the benefit is that no additional power instruments, such as file belt sanders or die grinders, need to be bought.

Cartridge rolls, flap discs, spiral bands, or thin abrasive belts may work well for flattening and blending the weld bead at the corner. Corner weld beads can be cleaned up or ground using spiral bands and cartridge rolls installed on a pencil or die grinder if one end of the welded corner is open and accessible. Carbide burrs and mounted points on a die grinder are other functional options.

A file belt sander's thin abrasive belt could reach inside and grind a huge weld bead on a corner. This method works better on larger projects because the desired completed radius of the filet needs to be greater than the diameter of the spiral band, cartridge roll, or contact wheel on the file belt sander. Because an abrasive belt has a larger surface area for abrasion, it will endure a lot longer than spiral bands, carbide burrs, mounted points, or cartridge rolls. It would take a lot of mounted points, carbide burrs, spiral bands, or cartridge rolls to grind and finish a long corner weld.

The edge of some flap discs mounted on an angle grinder can clean and grind the corner beads on a corner weld where both ends are open. Some of the abrasive flaps on flap discs that might grind into corners are visible or extend slightly past the fiberglass backing. Start grinding with a finer grit flap disc and use light pressure, as a coarse flap disc might over grind the weld or leave holes outside the weld.

3. ABRASIVES FOR POLISHING AND BUFFING

Fabrications made of bronze, aluminum, and stainless steel are frequently polished and buffed to create a surface finish that resembles a mirror. These metals don't need extra protective coatings because they resist corrosion in a variety of situations.

A polished surface is achieved by using a progression of abrasive goods that get finer or have larger grit sizes. A bright, mirror-like surface can be achieved by buffing.

Steel alloy welds that are going to be electroplated will likely require refinement to a polished or buffed finish in order to get the desired brightness and brilliance on the surfaces that are plated with nickel or chrome. Because electroplated layers are so thin, the initial surface finish determines how the plated surface looks. Polishing is not required if you want a sanded or brushed surface with a protective plating layer. A similar procedure would be needed for anodized aluminum weld surfaces.

The coarse scratches from earlier weld grinding, blending, and smoothing stages can be removed or blended out using finer grit abrasive belts, abrasive discs, and nonwoven abrasive before a welded product is rubbed to create a glossy or polished surface. You may want to use 80 or 120-grit flap discs or fiber discs to further finesse the scratches if the weld was first flattened with a 40-grit flap disc.

Subsequently, the surface can be further polished with non-woven surface conditioning flap discs, finer grit-coated abrasives, or both. For example, a medium (120–180 Grit) nonwoven flap disc and then a fine (280–360 Grit) nonwoven flap disc might be used to remove the coarse scratches.

When polishing aluminum welds, the surface should be ready for buffing by using an ultra-fine surface prep disc after finishing with a fine grit surface preparation wheel. However, depending on the exact finish or appearance, the finish from the ultrafine nonwoven wheel can be appropriate.

Before buffing a part with a buffing compound, "polishing belts' or finer (150–600 grit) ranges of abrasive belts are commonly used in a "polishing" step. Moreover, swirls and scratches are eliminated using non-woven belts.

To achieve a satin or brushed finish similar to that of stainless steel refrigerator doors, a polishing abrasive belt or non-woven wheel or belt may be utilized in some situations. Suppose you want to handle or touch your product. In that case, a satin finish is usually a preferable option because highly polished, glossy metal surfaces are more likely to show fingerprints and smudge marks.

Using abrasive drum sleeves or abrasive flap wheels for blending and interleaved and nonwoven flap wheels for scratch removal, satin or linear finishes can also be achieved on welded structures. These drum-shaped abrasive goods are used with power tools for surface conditioning, also referred to as drum grinders or sanders, and linear or contour surfacing tools.

The abrasive grain is present in buffing compounds, which are oily or waxy sticks. They come in a range of grades or grit sizes. The very fine scratches left behind by disc, belt, or non-woven polishing or smoothing are removed using coarser grade "cut buffing" compounds. A bright mirror surface is then achieved by final buffing with a "color buffing" compound, which contains incredibly fine abrasive grains.

Buffing drums, felt polishing discs, or felt flap discs, are the most sensible options for a large flat welded project. If your welded item can be handled in your hand, buffing wheels are usually operated by benchtop buffing machines for metal things that are portable and brought to the wheel. 

4. ABRASIVES FOR COATING SURFACE PREPARATION

Whether you're welding a bike frame out of high-strength steel tubing, welding a vehicle body repair, welding a patio chair, or creating a welded shelf for your living room, painting, and coating is the last stage in many welding projects.

A protective coating or paint layer is necessary for steel welding projects in order to both prevent corrosion and enhance the overall appearance. In most cases, a smooth or polished finish will work well whether your welding project is made of titanium, aluminum, or stainless steel. If the project will be used in an external application that is wet or salty, even aluminum would benefit from a protective coating. 

Paint, powder coatings, and high-build coatings may not require or benefit from an extremely smooth surface, although electroplated coatings could need one for a mirror-like appearance. Actually, undercuts from a rougher surface can help a coating stick to the surface more effectively. High-build liner materials and thicker powder coatings don't actually require an extremely smooth surface. To recap, the key to ensuring that your paint or coating sticks to a surface is adequate cleaning and surface preparation. This is similar to creating strong adhesive bonds or sound welds.

Abrasive fiber discs, abrasive belts, wire brushes, flap discs, and nonwoven abrasive materials are just a few of the many abrasives that can be used to clean and prepare a joint surface before painting.

CONCLUSION

Because abrasive grinding, cutting, and finishing are necessary at every stage of the component-making and joining process, abrasives play a significant role in fabrication and welding.

All operating guidelines and speed restrictions for abrasive materials, power hand tools, and grinding gear should be adhered to in order to use these products in fabrication and welding efficiently and safely. Because they take less time to build, prepare joint surfaces, rectify weld faults, and finish completed welds, abrasives, and grinding, they lower the cost of welding and joining.