Mig welding is characterized by sparks and spatter flying all over the place. It looks great on movies, but when we are doing the welding we realize spatter is a bad thing. It creates more work by increasing clean up time, it wastes material, and it can burn you if you are not wearing the right PPE. It is almost impossible to eliminate spatter in MIG welding, but we can certainly reduce it by understanding what causes it in the first place.
Most of us don’t have the option to buy the latest technology in welding equipment to eliminate spatter. We have to weld with what we have. So we are not going to talk about how equipment can help eliminate spatter. This list are items that you can change right now and for free.
7 Causes of Spatter:
1. Incorrect settings – procedures that are out of whack will cause spatter. Amperage, voltage and electrical stick out a crucial.
Amperage in GMAW is determined by your wire feed speed. Running amperage that is too high will cause spatter. To correct either lower the amperage by decreasing the wire feed speed or increase the voltage.
Per the above, if your voltage is too low your spatter levels will increase. Increase your voltage until spatter decreases.
- Electric Stick Out (ESO):
Electrical stick out is the distance from your contact tip to the work piece. When mig welding you want to be around 3/4″. A bit more for high amperage. Excessive stick out will increase spatter somewhat, but it will create bigger problems (porosity due to lack of shielding gas and lack of penetration).
2. Work angle too steep – there is a debate on whether pushing or dragging while mig welding is the way to go. Regardless of which you prefer make sure your drag (pull) or push work angle does not exceed about 15 degrees. At times there is no choice if reach is a problem. But when you can control it do not exceed 15 degrees. Steep angles generate a lot of spatter.
3. Surface Contaminants – rust, oil, paint and other surface contaminants will create spatter. Clean surfaces as best as possible prior to welding.
4. Mode of Metal Transfer – Short arc and globular transfers are modes of metal transfer that produce a lot of spatter. To drastically reduce spatter you need to achieve spray transfer. To do this you need a minimum of 83% argon in your shielding mix (a typical mix would be 90/10). However, you also need to be above the transition currents for the diameter of wire you are running. Smaller machines will not be capable of this.
5. Erratic Feeding – when the wire feeder cannot feed wire at a constant speed there will be fluctuations in amperage that will drastically affect the arc causing a lot of spatter. Make sure you don’t have any feeding issues. For help in correcting this problem take a look at Troubleshooting Erratic Wire Feeding.
6. Quality of Consumables – some applications can live with high levels of spatter, others can’t. In robotic applications and other situations in which wire consistency is critical shy away from the cheap-low quality wires. A single spool or drum may be consistent, but across several spools or drums there may be variations in wire diameter, copper coating, and chemistry. Unfortunately AWS allows for such wide range of chemistry that even a coat hanger can be made into a mig wire. The best manufactures keep their own ranges and tolerances and thus produce better product.
7. Bad Shielding Gas – This is very uncommon, but shielding gases of low quality can affect spatter levels. What is more common is mislabeling (i.e. getting a 75/25 on a cylinder that has a 90/10 label), but even this is rare. The higher the argon content the smoother the arc. 100% carbon dioxide is cheap and provides good penetration profile, but it creates a lot of spatter.
If you think it looks too complicated to get rid of spatter take a look at what it can be costing you: The Real Cost of Welding Spatter
Finally a word on anti-spatter. Anti-spatter does not eliminate or prevent spatter. It simply allows the spatter to slide off the material and not stick to it. By using excessive amounts you can introduce other problems such as porosity. It is not bad to use it, but look into what’s causing spatter in the first place and take care of it.
Sources: AWS D1.1/D1.1M:2015 Structural Welding Code (Steel)