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WeldTips #1: Optimal Torch Angles in Robotic MIG Welding

Robotic MIG welding has revolutionized the manufacturing industry by providing enhanced precision, efficiency, and safety. A key factor in achieving high-quality welds with a robot is understanding the optimal torch angles and positioning of the welding torch.  Most robotic welders allow precise control of the torch angle while welding.   For optimal control of the torch angle a seven axis welding robot should be used.  While six axis robots can keep the torch angle consistent in most orientations,  complex weld paths may need to be broken into sections for the robot to reposition and restart.  Seven axis robots, however, allow more maneuverability in tight spaces and through complex weld paths.  In this article, we will delve into the importance of getting and maintaining the optimal torch angles.  We discuss when to use a drag or a push angle for optimal results.  Many factors affect the quality and appearance of a weld.  The tips that follow are guidelines and starting points when approaching a new weld.  They are not unbreakable laws.    

 

Torch Angles and Their Significance

 

Torch angles play an important role in MIG welding. They directly affect the weld bead shape, penetration, and overall quality of the weld.  Using the optimal torch angle applies to both manual and robotic welding, however, when welding manually it can be difficult to maintain the consistent torch angle.  A welding robot is able to maintain the torch angle perfectly throughout the path of the weld.  Now, let’s get into drag and push angles and when you should and shouldn’t use them.

 

Types of Torch Angles

 



1. Drag Angle

 

A “rule of thumb” to refer to when deciding between a drag or push angle is, “if there’s slag you should drag”. This rule of thumb exists because using a push angle when there is slag will often result in slag getting trapped under the weld, causing defects. Flux-cored arc welding and stick welding are the most common slag-producing welds that you usually shouldn’t push. More on this later.

 

The drag angle is a technique where the MIG welding torch is tilted backward in the direction of travel. It will typically produce a more convex weld with steeper transitions at the toes and have deeper penetration than if you use a push angle.  It is not necessarily a bad idea to use a drag angle with a filler metal that does not produce a slag, but it is good to be aware of these properties before welding. Drag angle is most commonly used on level welds.  Vertical welds, running down hill, can also use a drag angle, but usually only on thin materials at fairly high torch speeds in order to produce a shallow penetration weld.

 

2. Push Angle

 

The push angle involves tilting the MIG welding torch slightly forward in the direction of travel. Using a push angle will produce a flatter weld deposit and typically have a better transition angle at the toes of the weld.

 

For vertical weld and running uphill, it is usually recommended to push, even when welding with a filler metal that produces slag. Remember how pushing this kind of weld causes the slag to get trapped in the puddle? This is not an issue in this case because gravity will pull the slag away from the weld pool. Flux core wires work great here because they are able to weld at much faster speeds than other methods due to the slag supporting the molten metal during welding.

 

Recommended Angles

The specific angles for drag and push techniques can be varied based on personal preference and joint geometry. As a general guideline, 5-15 degrees is the norm for both dragging and pushing.   A steeper angle of 10-25 degrees is often used when doing vertical welds to help fight gravity. Too steep of an angle however, can produce poor aesthetics of a weld and even defects due to insufficient shielding gas coverage.  They directly affect the weld bead shape, penetration, and overall quality of the weld.

The data sheet for the filler material you are using will often give guidance.  The tips on the datasheet are also a helpful resource even when welding with products you are familiar with. If a unique wire requires a specific technique, you’ll probably find some recommendations on the data sheet.

 

Summary

Understanding the importance of torch angles and robot positioning in MIG welding is important for achieving superior weld quality.  Embracing these techniques will help manufacturers achieve the best possible welds,  and maximize the consistency, speed and quality of robotic welds.


 

From the Productive Robotics Weld Team

This article was written by our Weld Team. Productive Robotics is the leading American manufacturer of collaborative robots for welding, CNC machine tending, and far more. All of our welding robots feature;

 

• Zero programming. No robot experience needed.

• Teach a weld faster than it takes to weld by hand

• Repeat the same weld perfectly every time

• Manual weld trigger built in

• Online Support by experienced, degreed welders

 

Have a question or need more information? Talk with a welding and robotics expert: 805.244.9300 or download this guide.


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