It's All About The Angles!
By Matt Brooks
March 17, 2008
A common tactic for many welders, even those with years of experience, is to change their welding torch angle based on what is the most comfortable for them. This usually results in a relatively good starting angle that ends up very different form the original set up, and causes the welder to make changes to their welding speed or welding method by the end of the weld.
Torch angles are one of the most overlooked variables in modern welding. The torch angle, which is the angle of the welding torch relative to the direction of travel, can have large effects on the structure and bead appearance. Proper adjustment of the torch angle can take a spattery, unstable weld and change it to a smooth controlled clean weld; likewise, a poor torch angle can ruin weldments. The three major welding angles are described below.
The Push Angle
A push angle, also referred to as the forehand direction or lead angle, means that the arc or puddle is ahead of the torch when welding in a specific direction. This angle is preferred by most manual welders and robotic programmers due to the ease of welding or programming. The final bead appearance typically has a very desirable appearance.
Welding with a push allows the welder to watch the welding pool as it forms with out being blocked by the torch. The push angle method offers some distinct welding advantages such as:
1. Broad / Flat Bead appearance (more likely to produce concave welds).
2. Shallow Penetration.
3. Better gas shielding that helps clean the surface to be welded.
4. Slight preheating to the welding surface before welding.
5. Slower Bead Cooling.
The above advantages of a push angle are a result of the direction of forces, heat, and shielding gas being focused ahead of the weld toward the surface to be welded.
Push angles are not without drawbacks. Since the direction of forces is forward, any spatter generated will be forced into the atmosphere rather than back into the weld pool, creating more visible spatter. Additionally, push angles tend to cause more undercut along the weld toes. In some rare cases, the slower cooling rate, which is a relatively small when compared to other angles, can cause a weakening of the material.
The Pull Angle
Pulling, dragging, or using a lag angle refers to moving with the torch body ahead of the arc and the puddle following behind. This has also been called the backhand welding technique, since the welding puddle is in the back. Since the puddle is behind the weld, most welders avoid this process, since the arc is difficult to see and sudden adjustments are 
harder to make.
Most of the advantages of using a pull angle are simply opposite of the push angle and are used for specific applications. These include:
- Deeper penetration.
- Slightly cooler welds.
- Narrow bead width.
- Better spatter control.
In some cases, such as downhill welding or welding with galvanized materials, pull angles offer much greater control and are often the only method recommended for those applications.
There are some key downsides to using a pull angle when welding. As previously mentioned, the arc is more difficult to see and hence compensating or adjusting the weld is more difficult when compared to a push, although with enough experience and practice the difficulties are insignificant. Additionally, when welding with a pull angle, the weld bead tends to hump more and may cause overlap if not properly fused at the weld toes.
The Straight Angle
The third angle is the straight angle, which is the median between the pull angle and push angle. The straight angle can help compensate for problems experienced with either push or pull angles, while lessening the draw backs from the opposing angle. A welder must be careful when using a straight angle since most of the forces are directed at the weld and can cause burn through or blow through if a gap is present.
The Venturi Effect
The Venturi effect is a phenomenon that occurs when the welding torch angle is too great. This can occur with both push and pull angles. During this effect, the torch angle sucks in air from the atmosphere, which then mixes with the shielding gas. The new mixture of gases is then forced out onto the weld causing contamination and porosity. This typically occurs when angles greater than 45° are used.
Determining the Best Angle
The best welding angle for each type of joint will vary slightly depending on thickness, penetration requirements, desired bead appearance, type of materials, etc. Review the advantages and disadvantages listed above to help determine if a push, straight, or pull angle should be used. Most companies will recommend that a welder stay between 0° and 15° away from 90°, hence giving 30° of angle for adjustment. This may vary some for certain materials such as aluminum, where the recommended push angle is between 10° and 30° (to help the weld stay clean).
The other angle of concern is the Work Angle. The work angle refers to the angle relative to the base materials being welded. Another way to think of the work angle is the torch angle rotated 90° or the tilt of the torch.
The work angle is determined by the type of joint and material thickness. Typically, the work angle is set evenly between the two surfaces, then offset if the thicknesses are different.
For example, in a fillet weld, between two 3mm sheets, a 45° work angle is commonly used to spread the weld evenly between the two materials. If the thickness of the base material is increased then the work angle must lean toward that material. This puts a slight focus on the thicker material, which will commonly require more heat and energy to fuse properly. Similar to the torch angle, the work angle may vary to suit the weld requirements or desired appearance.
Where To Go Next
To the lab! The best way to emphasize the points discussed in this article would be go and make some welds. Pay particular attention to your torch angles, and experiment with changing the angles slightly for different effects. The worst thing you can do is make a bad weld, and if that happens, try and understand why this happened. Can you see the weld pool moving while using a push weld? Or need some help getting the timing down on a pull angle? Get out there and try them out!
