A range of factors can cause weld spatter but, ultimately, it comes from the weld pool, the welding wire or a combination of both.
For example, the welding puddle can be disturbed and splash molten material or the welding wire can scatter the base metal from the weld pool before fusion. Alternatively, the weld bead can break off and scatter as a result of arc repulsion.
As noted above, weld spatter can be caused by a variety of different factors, although the main cause is a disturbance in the weld pool as the wire is transferred into the weld. This is typically caused by the amperage and voltage settings used during welding. If the voltage is too low or the amperage too high for a wire and gas combination it can mean that the arc is too cool to keep the wire and pool molten, causing a stubbing effect on the wire. This can happen at both low and high current ranges, causing a popping that creates spatter and is sometimes referred to as ‘arc explosion’ by welders.
The welding gas selection can also result in spatter being generated. CO2 is cost-effective as it increases the arc energy, but it also creates more spatter. Argon is often used to counterbalance the CO2 spatter.
Other causes of spatter include when the weld droplet makes contact with the weld pool, scattering the base metal before fusion during short arc processes. Alternatively, an arc repulsion force can cause the weld bead to break away and scatter.
Of course, weld spatter can also be caused by a weld droplet simply splashing into the molten weld pool, especially in a globular transfer mode.
Causes of weld spatter can be worsened further by factors including poor quality welding wire, overly long or short arcs, incorrect mixtures of gas, poor welding surface conditions, incorrect welding torch angle, improper wire feed speed, grounding location, loss of shielding gas or wind, and moisture in the atmosphere.
Weld spatter is formed by droplets of molten material that has been splashed or scattered during welding, leading to the formation of unsightly globules of material.
Weld spatter can potentially causing burn injuries as the molten droplets travel through the air. As they cool, these droplets stick to the base material and surrounding area, causing imperfections on the surface of a material.
Spatter can be hazardous in industries that deal with oil, while the marks, cracks, damage or pores left on the surface can lead to corrosion. This can be alleviated with the use of anti-spatter spray.
It is possible to reduce spatter, but different causes require different techniques to solve the problem.
As such, we will look at common causes of weld spatter and the methods that can be used to solve them:
1. Metal and Filler Composition
Cheaper metals can contain filler materials to reduce costs, but these can sometimes make the metal unweldable, leading to spatter. The same can be said for your own filler materials, with cheaper rods and wire sometimes-including materials that will make them prone to spatter.
Solutions: The simplest solution is to make sure the material and products you are using are of a high enough quality to prevent or reduce spatter.
2. Dirt and Contamination
Dirt or contamination can cause molten metal to spit, leading to weld spatter. This contamination can include protective coatings and oils that need to be removed in order to reduce spatter. Welding wire and rods also need to be kept clean to reduce spatter, which can be caused by dirt, rust or contaminated filler materials.
Solutions: Ensuring that dirt, oil and rust are removed on each side of the weld, using a wire brush, grinder or flap wheel to bring the metal up to a clean, bright finish. You should also store your filler materials in a clean, dry place so that it doesn’t rust or become contaminated by dirt, dust or oil.
3. Welder Settings
Although it is possible to use general rules of thumb when it comes to welder settings, in reality, each weld has its ideal settings, with experience teaching you how to make the necessary adjustments for a particular weld. If there is not the right amount of heat and penetration the welding puddle can be disrupted and create increased spatter.
Welder settings differ between TIG and MIG welding, with MIG techniques requiring the wire feed to be at the correct speed. If it is too fast, the metal wire will hit the molten pool and cause it to splash and spatter, but if it is too slow and the wire is vaporised before it reaches the weld, there will be spatter.
Using the wrong polarity can also cause excessive spatter, so don’t forget to check that you are set for the right type of wire, whether solid or flux cored. Plus, make sure the gas flow rate, blanket and type of shielding gas are correct, as these factors can also increase spatter.
MIG Solutions: Make sure you have checked the polarity of your MIG welder so that it is working for the correct type of wire and ensure the current and/or voltage are providing good heat and penetration for the weld. These settings need to be working alongside a wire speed that suits your skill and the requirements of the weld. Also, make sure that there is the correct amount of wire sticking out from the nozzle so as not to spatter. This can vary depending on the geometry of the weld, but is generally around 3/8 of an inch. Further to this, you need to make sure you are using the correct gas for the weld and that there is a good, consistent gas blanket across the weld area.
Stick / TIG Solutions:
Travel speed is important for avoiding spatter with these types of weld. This is linked to the current and/or voltage settings; if it is too hot you must move quickly, which can cause spatter. However, if it is too cool the welding will be rough and can cause sticking, leading to an unsightly, spattered weld.
With both techniques, the key is in practice and experience, so it is a good idea for beginners to practice settings on scrap metal, slowly changing the settings to find the best ones for your welds.
4. Welding Technique
As noted above, the speed at which you move with either MIG or TIG welding can increase the amount of spatter. This can be a matter of technique, which can only be improved by practice. However, there are other specific factors to consider too, for example, your MIG will create more spatter as it passes over angle of 15 degrees. With TIG welding, meanwhile, if your arc is too long, the amount of weld spatter will increase.
MIG Solutions: Of course, good technique is key to creating good welds, which includes the travel direction with MIG welding. Consistently higher heats can be achieved by pulling the weld, while pushing the weld will deliver better heat distribution. While this varies according to the material being used, it can cause spatter if you get it wrong. As highlighted above, the angle of your welding gun should not exceed 15 degrees; if it is too steep you will create more spatter. Welding speed is also important, neither too fast nor too slow as it will not only create more spatter but can also damage the quality of your weld.
TIG Solutions: Welding speed is also important with TIG or stick welding. If you move too quickly, you will create more spatter and can be caused by your current or voltage being set too high. The arc length also needs to be correct, a rule of thumb is to keep the arc length equal to the metallic core of your electrode.
5. Equipment Issues
Equipment issues can also be a cause of spatter, whether that is an erratic wire feed, poor grounding, lack of shielding gas flow, or a worn or badly sized contact tip. Any type of issue that affects the current, filler feed or shielding gas can increase weld spatter.
Solutions: Quite simply, to produce high quality welds without spatter it is important to make sure your equipment is working properly. This includes cleaning your ground clamp so that it makes good contact and the current doesn’t fluctuate. With MIG welding, you should make sure your wire feed is at the correct tension with no snags or restrictions on the feed. You should also make sure the hoses regulators and gas ports are connected, clear and working correctly for the shielding gas to flow smoothly. Equally, the contact tip should be the right size and in a good condition.
Despite all of the precautions, you may still end up with some weld spatter that needs fixing. There are a few methods that can be used to clean weld spatter, although they can be time consuming and tedious, which is why avoiding spatter is always the better option.
Techniques for fixing weld spatter include:
- Grinding: Spatter can be cleaned up by grinding, although this can be time consuming. However, if you need to use an angle grinder as part of your finishing work, it may well be worth taking the effort to just tidy up any spatter at the same time
- Chipping Hammer / Spatter Chisel: Hand tools such as a chipping hammer are another method for removing spatter. They are specifically designed to quickly remove weld spatter without damaging the base metal
- Anti-Spatter Srays, Gels and Tapes: Rather than having to remove any spatter after welding, you can use anti-spatter sprays, gels or tapes to stop the spatter from sticking in the first place. When using tapes, it is often recommended to use aluminium tape as it can withstand the heat of the spatter and won’t melt, unlike plastic tapes.
While a small amount of weld spatter is not generally seen as a bad thing (especially if it is cleaned up after), too much spatter can be a genuine problem.
Not only can weld spatter lead to downtimes for clean-up, but it also wastes materials. In addition, weld spatter will burn if it lands on your skin, so care must be taken not to get hurt!
Weld spatter can count as a defect if it exceeds the amounts specified by a project’s specification or a welding standard.
Generally speaking, minimal spatter is usually just a minor issue but, if there is a lot of spatter, it can be classed as a defect.
Weld spatter may seem like an everyday hazard for welders to contend with, but there are several different causes of spatter. In addition, spatter can be dangerous and be seen as an unacceptable defect for some projects or standards.
Because of this, it is generally best to try and reduce spatter through a range of methods, from changing your welding technique to checking your settings and the state of your equipment.