7 Common Sheet Metal Welding Problems and How to Fix Them
Sheet metal parts are coveted for their simplicity, affordability and aesthetically pleasing build from thin plates of metals. The process efficiency, ease of modification, malleability and lightweight also make them ideal for a wide array of applications.
Sheet metal fabrication services in china will almost certainly involve some form of welding. As simple as this may sound, there are common issues that can arise as a result of improper technique, wire delivery and even arc voltage. As welding remains one of the most fundamental processes when making sheet metal parts, here are some of the most common issues that you may face and how to fix them.
Undercuts in sheet metal welding will usually occur as a result of applying high arc voltages to the sheets. It is a direct consequence of welding under high voltage, the use if incorrect electrodes or when the welding is done at suboptimal or inaccurate angles. Welding at very quick rates may also result in undercuts. To prevent undercuts in sheet metal fabrication, ensure that you are welding at the appropriate speed, monitor the electrical voltage and avoid the use of electrodes that are of higher capacity than required.
Undercuts may also be avoided by keeping the electrode at a reasonable distance from the vertical plate when making a horizontal weld.
Spatter, which is one of the most common welding problems in sheet metal manufacturing, arises due to the dropping od liquid/molten metal material around the welding arc. It occurs due to the welding at currents higher than required, inadequate gas shielding or incorrect polarity.
Spatter can be prevented by reducing the current applied when welding as well as the length of the arc. Also, try to confirm the shielding gas type, flow rate and polarity parameters before starting your welding process. Increasing the torch-to-plate angle and ensuring that your gas nozzle is free from dirt and debris can also lower the tendencies of spatter while welding.
Porosity is generally caused by the absorption of moisture, oxygen, hydrogen and nitrogen gases into the molten weld pool. On solidification, these gases remained trapped in the welded sheet metal, leading to surface porosity in the part.
Porosity in sheet metal welding may be caused by the presence of materials such as paint, grease, rust and impurities. It can also result from the inadequate gas shielding when welding, impaired base metal, poor electrodes and improper shield coverage. Avoiding porosity can be through re-baking, cleaning the weld plates, ensuring that the gas nozzle is dry and moisture free and using fresh welding materials. Also, allow sufficient puddling time, use the right current and electrode, checking shield gas and using longer arcs and check for impurities in your base metal.
4. Welding cracks
Cracks are very problematic in sheet metal welding. Because of this significant effort required to correct them, it is often easier to prevent them. Cracks in sheet metal parts will result in structural failure, deformation and will eventually expand when left unattended.
To prevent welding cracks, ensure that you have taken all the required measures of cleaning, filing, grinding, deburring and drying the edges of the welding plates so they can be brought together seamlessly. You can also avoid cracks in your sheet metal parts by applying the appropriate amount of heat and temperature to the sides of the sheet metal joints.
5. Fragile welds
Fragile or brittle welds are welding in sheet metal that are not as strong as they should be. These fragile welds are caused by welding with bare electrodes or electrodes that are not appropriate for the operation. They can also be caused when the sheet metal becomes hardened by air or a problematic preheating system. The brittle nature of these welds mean that they stand a chance of damage and breakage. To prevent brittle welds, avoid welding operations at excessive currents and use arc electrodes that are shielded. Use the right welding technique, handpiece maneuver and try as much as possible to make your travel rates and passes smoother.
6. Poor penetration
Poor penetration is caused when sheet metals are welded at speeds that are too fast for the operation. It is also caused by using welding currents that are too low or electrodes too large. To prevent poor penetration during welding, ensure that you use the appropriate electrodes and current, weld at the right speed, don’t rush and allow for proper gaps at the bottom of the weld.
Warping is the effect of excess heat build-up in a part of your sheet metal. It is caused by overheating at joints, faulty part clamping and faulty preparation. It is also caused by the shrinkage of weld metals. The effect of warping on your sheet metal part is part distortion, stress and structural integrity.
Warping can be controlled by welding at appropriate temperatures, using intermittent welding techniques, employing high-speed, moderate penetration, avoiding excess space between parts, proper clamping, making fewer weld passes and peening joint edges before welding.
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