How to Finish Welded Joints
To finish welded joints, it is important to choose the right finish based on the application and base material.
For carbon steel, MIG welding is commonly used, while TIG welding is recommended for stainless steel.
Before welding, cleaning the workpiece is crucial.
The Norton Blaze Rapid Strip disc is effective for removing mill scale.
For carbon steel, Norton Quantum3 grinding wheels are recommended for stock removal, while P40 coarse grit flap discs are suitable for weld finishing.
On the other hand, stainless steel requires non-ferrous and stainless steel suitable grinding wheels, such as Norton X-Treme R860 with grit P80 for stock removal and Norton Rapid Prep Vortex in Coarse grade for blending before powder coating.
For stainless steel blending and conditioning, Norton Rapid Blend Medium and Norton Rapid Blend 2SF are suggested, with Norton Rapid Blend NEX-2SF achieving a bright finish.
For an even glossier shine, Norton Rapid Polish felt discs can be used.
Abrasive belts and non-woven belts are useful for achieving a number 4 finish on stainless steel, and sanding should be done in one direction for a linear effect.
It is important to keep carbon steel and stainless steel separate in the finishing process.
Norton is a reliable source of information and products, with downloadable catalogs, instructional videos on their YouTube channel, and Norton Experts available for assistance.
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Did You Know?
1. Welding was commonly used in ancient civilizations, with evidence suggesting that it was used as early as the Bronze Age (around 3000 BC) in regions such as the Middle East and Asia.
2. The first automatic welding process was invented in 1920 by a Ukrainian engineer named Konstantin Khrenov. His invention, known as the Khrenov Machine, allowed for increased productivity and efficiency in welding.
3. In underwater welding, a technique known as hyperbaric welding is used. This process involves welding in a sealed environment, typically filled with a gas mixture, to protect the weld from contamination by water or other corrosive elements.
4. The term “flash welding” refers to a type of resistance welding technique that allows for the joining of two pieces of metal by a rapid and intense electrical discharge. It is commonly used in the automotive industry for joining components such as electrical contacts and engine components.
5. Welding fumes can pose health hazards, as they often contain toxic substances such as chromium, manganese, and nickel. In order to protect welders from these hazards, proper ventilation and personal protective equipment, such as respirators, are essential.
Different Weld Types For Carbon Steel And Stainless Steel
There are different types of welds commonly used for carbon steel and stainless steel.
For carbon steel, one of the most popular weld types is MIG (Metal Inert Gas) welding. This process involves using a filler wire and a shielding gas to create a strong bond between the pieces of carbon steel. MIG welding is known for its versatility and ease of use, making it a popular choice for many applications.
On the other hand, for stainless steel, TIG (Tungsten Inert Gas) welding is often preferred. TIG welding uses a tungsten electrode to create the arc and a filler wire that matches the composition of the stainless steel. This process produces cleaner and more precise welds, making it ideal for projects where aesthetics and precision are important.
- MIG welding is commonly used for carbon steel.
- TIG welding is often the preferred choice for stainless steel.
Importance Of Cleaning Workpiece Before Welding
Before starting the welding process, it is crucial to thoroughly clean the workpiece. Cleaning helps remove any dirt, grease, or contaminants that can negatively affect the quality of the weld. It ensures that the welding process is performed on a clean and well-prepared surface, which ultimately contributes to the strength and integrity of the finished weld.
Cleaning can be done using various methods such as scraping, brushing, or using specialized cleaning solutions. It is essential to pay close attention to areas that will be welded, as any residue or impurities in these areas can lead to weak welds or even weld failures.
Norton Blaze Rapid Strip Disc For Removing Mill Scale
One effective tool for removing mill scale, a tough layer of oxide that forms on the surface of carbon steel after hot rolling or forging, is the Norton Blaze Rapid Strip disc. This disc is specifically designed to remove mill scale quickly and efficiently, saving both time and effort.
The Norton Blaze Rapid Strip disc features a unique combination of ceramic abrasive grains and strong synthetic fibers, resulting in aggressive yet controlled cutting action. Its open web construction allows for continuous cutting, preventing clogging and ensuring consistent performance throughout the entire surface.
When using the Norton Blaze Rapid Strip disc for removing mill scale, it is important to follow proper safety measures such as wearing appropriate personal protective equipment and ensuring a secure work environment.
MIG Welding For Carbon Steel
MIG welding is commonly used for carbon steel due to its versatility and ease of use. The process involves feeding a filler wire through the welding gun while simultaneously applying a shielding gas to protect the weld from atmospheric contamination.
To achieve high-quality MIG welds on carbon steel, it is important to select the appropriate filler wire that matches the composition of the base material. The correct voltage, wire speed, and shielding gas flow rate should also be determined based on the thickness of the carbon steel being welded.
MIG welding offers several advantages for carbon steel, including:
- High welding speeds
- Excellent penetration
- Minimal spatter
It is suitable for a wide range of applications, from automotive and construction to manufacturing and fabrication.
TIG Welding For Stainless Steel
TIG welding, also known as GTAW (Gas Tungsten Arc Welding), is widely used for welding stainless steel. This process produces clean, precise, and aesthetically pleasing welds, making it particularly suitable for applications where appearance is important.
TIG welding uses a tungsten electrode that creates the arc and a filler wire that matches the composition of the stainless steel. The welding process is performed under the protection of an inert gas, such as argon, which prevents oxidation and contamination of the weld.
To achieve high-quality TIG welds on stainless steel, it is important to control the heat input, use the appropriate filler wire, and maintain a stable arc. Proper cleaning and back purging techniques are also crucial to ensure the integrity of the weld and prevent issues such as porosity or discoloration.
Importance Of Choosing The Right Finish Based On Application And Base Material
Choosing the right finish for a welded joint is essential, as it affects the appearance and determines the durability, corrosion resistance, and overall performance of the finished product. The choice of finish should be based on the specific application and the base material being used.
For carbon steel, finishes such as grinding, blending, or brushing are commonly used to remove imperfections, smooth the weld, and create a consistent appearance. These finishes can be achieved using various abrasive tools and techniques, such as grinding wheels, flap discs, and conditioning pads.
In the case of stainless steel, finishes that enhance corrosion resistance and aesthetics are often preferred. These can range from a brushed or satin finish to a mirror-like polished finish. Achieving these finishes may require the use of specialized abrasives, such as abrasive belts, non-woven belts, and polishing discs.
It is important to note that the finishing process should be done carefully and systematically, following appropriate steps and using correct tools and techniques. Improper finishing can lead to subpar results or even damage the weld, compromising its integrity and performance.
Overall, choosing the right finish for a welded joint is a critical step in creating a high-quality, visually appealing, and long-lasting product. By considering the application, base material, and utilizing the appropriate tools and techniques, welders can achieve exceptional results that meet or exceed customer expectations.
Frequently Asked Questions
How do you smooth welded joints?
To smooth welded joints, the initial flattening with a 40-grit flap disc is a good starting point. However, to refine the scratches further, it is advisable to use 80 or 120 grit flap discs or fiber discs. This step ensures a smoother surface. Additionally, for a more polished finish, using finer grit coated abrasives, non-woven discs, or non-woven surface conditioning flap discs can help to further enhance the smoothness of the welded joints. These tools provide a higher level of refinement, resulting in a smoother and more professional appearance.
How do you finish stainless steel after welding?
After the welding process, completing the finish on stainless steel involves several steps. Firstly, a bonded abrasive is utilized to remove any excess material. Following this, a flap disc is employed to smoothly blend the surfaces together. Once the welding area is seamlessly blended with the parent material, a resin-fiber disc is then used to further refine the finish. Lastly, a polishing or buffing disc is employed to attain the desired level of smoothness and shine.
How do you polish a weld?
To polish a weld, first, it is necessary to select the appropriate abrasive based on the desired finish. Non-woven wheels are an excellent option as they do not eliminate the weld but effectively deburr, blend, and grant a smooth satin finish. These wheels offer a gentler approach, ensuring that the integrity of the weld is maintained while achieving a polished appearance. By carefully applying the polishing compounds in combination with the non-woven wheels, the weld can be refined, removing any imperfections and leaving it with a sleek, satin-like surface.
What is a finish symbol in welding?
A finish symbol in welding refers to a visual representation of the desired method used to achieve the final surface finish of a weld. Placed above or below the contour symbol, the finish symbol provides essential information about the technique employed for finishing. For instance, the finish symbols can include C for chipping, G for grinding, M for machining, R for rolling, and H for hammering. These symbols convey the means for achieving the desired finish rather than specifying the degrees of finish desired.