core wire ppt

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welding

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When it comes to making decisions about the fabrication process, many companies have begun to look not just at the costs accumulated in the weld cell, but also at the total cost of the welding operation. Rightly so. Pre- and post-weld activities, product flow, inventory management and equipment selection can all have a significant impact on quality, productivity and profitability. in this industry, the cost of materials and labor is a constant concern for Douglas Banks. How does a business owner balance the need for impeccable craftsmanship and the desire to keep costs down ? n contrast to self-shielded flux cored wire, metal cored wire contains more iron powder in the flux, which helps increase deposition rates (the amount of wire burned, measured in pounds per hour), deposition efficiency (amount of wire used that goes directly into the weld) and faster travel speeds Metal-cored wire consists of a hollow metal sheath filled with metallic powders, alloys and arc stabilizers, benefits such as lowering oxidation, providing higher impact strengths and reducing silicon deposits in the final weld This mechanical and chemical structure causes the wire to operate differently than solid wires, for example, which are solid throughout the entire cross section. It also generates different arc and weld profile characteristics.

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During the welding process, metal-cored wire carries the current through the outside metal sheath, resulting in a broad, cone-shaped arc (see figure 1) that creates a wide penetration profile and is capable of easily bridging gaps in the weld joint. The wire operates in the spray transfer mode, during which it creates very small droplets that deposit in the weld puddle but generate little to no spatter. Companies can use metal-cored wire for single or multi-pass welding in the flat, horizontal and vertical down positions. Using a standard CV (constant voltage) power source, they can also use the wires in the overhead position. In most cases, metal-cored wire uses high argon shielding gas mixtures — a minimum of 75 percent argon is recommended (blended with a balance of CO2) and is typically available in diameters ranging from .035- to 3/32-inch. Metal-cored wire has a high burn-off rate that provides fast travel speeds and high deposition rates, especially in comparison to solid wires. It is also known to help minimize weld defects such as porosity, lack of fusion and undercut.

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Figure 1: Metal-cored wire produces a broad, cone-shaped arc that is capable of easily bridging gaps in the weld joint. Applications for which it is best suited, including those found in heavy equipment manufacturing, rail car fabrication, and food and petrochemical fabrication. The technology also works well on automotive exhaust fabrication, and wheel and chassis manufacturing. The wire's ability to excel in these applications is in large part due to the fact it can be alloyed for most every type of steel — from mild and stainless to low alloy. Metal-cored wire can often be used as an alternative to certain submerged arc or gas-shielded flux-cored wire applications. It can also be used in many of the same applications that employ solid wire, particularly those requiring single-pass welds that are 3 inches or longer, or applications welded in the flat and horizontal position using the spray transfer mode. Other applications where metal-cored wire works well include applications prone to burn-through; piping or other components where poor fit-up occurs and applications requiring aesthetic bead appearances.

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How can metal-cored wire reduce the hidden costs of welding? Metal-cored wire is capable of welding on a variety of material thickness (1/4 inch and above, especially), which often makes it possible for companies to standardize on a single diameter wire throughout the welding operation. This standardization can help minimize inventory and the time associated with managing it, as well as reduce downtime for wire changeover. It also lowers hidden costs in other ways. \ Metal-cored wire can weld through mill scale and rust and still produce very little spatter, so it helps eliminate activities like grinding, sand blasting or applying anti-spatter prior to welding. such pre-weld activities often cause bottlenecks that adversely affect the throughput of the fabricated part, reducing the overall productivity and profitability of the operation. grinding may cause greater operator fatigue and/or repetitive stress injuries that could increase insurance costs. Pre-weld activities like anti-spatter application can also create downtime for cleanup, since the solution is notoriously messy and frequently needs to be cleaned off of equipment and the floors.

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Compared to solid wire, metal-cored wire carries the current through the outside metal sheath to create a wide penetration profile. The wire also operates in the spray transfer mode, during which it creates very small droplets that deposit in the weld puddle but generate little to no spatter. ince metal-cored wire can minimize defects such as undercutting or lack of fusion, companies may be able to reduce reject rates, along with the amount of rework in post-weld areas. Less post-weld activity can increase the flow of completed parts to other stages of production, too, such as painting or coating, to help improve overall productivity. In the welding cell, the fast travel speeds and high deposition rates that metal-cored wire provides can frequently increase productivity, as well.  Improvements are most often seen in robotic and automatic welding applications,

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Metal-cored wire typically costs more than solid wire, A good first step is to identify bottlenecks in productivity that exist due to pre- or post-weld activities and calculate the costs of for labor and equipment associated with them. Companies should look at the current quality of the parts being produced and the cost associated with any weld defects like undercut or lack of fusion. The cost of rejected parts should also be considered, as should the overall production rates. If the costs for any or all of the aforementioned activities are unnecessarily high or just higher than desired, further investigation into metal-cored wires may be warranted.