What is Weld Spatter?
A very common occurrence in gas metal arc welding (GMAW) is the creation of what welders call "spatter," which is essentially droplets of molten material that are generated at or near the welding arc. Spatter is generally regarded as a nuisance and is a critical factor to consider when developing an application.
Why is Weld Spatter Problematic?
Spatter can cause numerous problems in most manufacturing processes. The most common problems are:
- Spatter balls sticking to work pieces or tooling
- Spatter burning workers' clothing and skin
- Loss of material from the arc and weld
- Excessive clean-up of spatter
Most manufacturers strive to reduce the amount of spatter generated, if not eliminate it all together. To resolve a problem you have to know why the problem is occurring - in this case what causes spatter.
Where Does Spatter Come From?
Spatter is caused by several factors. The main factor is a disturbance in the molten weld pool during the transfer of wire into the weld. Typically, this is caused by the relationship between amperage and voltage. This is usually seen when the welding voltage is too low or the amperage is too high for a given wire and gas combination. In this situation, the arc is too cold to keep the wire and pool molten and causes a stubbing effect of the wire. This can occur at both high and low current ranges.
Spatter may also be generated as a result of the gas selected. In GMAW, the use of CO2 increases the arc energy and is very cost-effective, but it creates more weld spatter. Argon is commonly used to counter balance the spatter generated from CO2. Figure 1 gives a comparison of CO2 welding to MAG welding at different current levels.
What Else Can Cause Spatter?
Other patterns that can generate spatter include:
- In a short arc process, the weld droplet contacts the weld pool and scatters the base metal before fusion
- When fusion occurs after short-circuiting and the weld bead heats due to a large increase in current. This is essentially the problem described above, where the amperage becomes too excessive for the given welding wire. This is also what most welders like to refer to as the "arc explosion" or the popping that causes spatter
- An arc repulsion force causes the weld bead to break off and scatter.
- Splashing occurs when a weld droplet falls into the molten pool. This is very common in a globular transfer mode.
- When the weld bead is affected by the magnetic repulsion force of the short circuit in the weld pool
Most of these factors can be controlled or restricted through various techniques. Recent research conducted by DAIHEN Corporation has led us to new technological developments that have greatly improved curbing of welding spatter levels.
What Factors Influence Spatter?
Additionally, there are a number of other factors that can worsen spatter generation. Some of these conditions relate to consumables, some are torch-related, and others are a reflection of production environments:
- Poor-quality welding wire.
- Incorrect gas mixtures.
- Poor welding surface conditions (such as oily parts, paint, rust, etc.)
- Improper torch angle
- Wire stick-out length
- Grounding location
- Wind / loss of shielding gas
- Moisture in the atmosphere
Usually, combinations of these factors cause an imbalance in the amperage and voltage. For example, oil on the parts being welded may cause a welding power supply to receive inconstant feedback and result in the power supply over- or under-compensating. To counter this, our D-Series come equipped with standard filtering systems to ensure a constant output of welding characteristics to control this relationship.
Have a question? Ask one of our experts!
Tech Tips is designed to help you with your production. We're always open to your requests, and will try our best to answer your questions in upcoming Tech Tips features. We also provide direct responses via email, so don't hesitate to ask!