Wednesday, October 15, 2014

Welding in today's industry...thoughts and tid bits

I continue to get a lot of inquiries regarding welding technique, varying from the ubiquitous "what are your settings" to "I saw a guy once do...is this right?" Sometimes these discussions occur in forum areas where I try to take a mentor-ship role in developing the knowledge and skills of those just dipping their toes into the trade. Here is a snippet I pulled from one such post that gives some of my perspective on the differing techniques used by professionals today...

This is where I choose to have a differing perspective, and why fabrication has so many paths to the same end.

Multiple elements have an effect on the overall creation of the fused joint that can be controlled by the operator; amperage, filler size, filler feed rate, rate of travel, angle of torch, and cleanliness.

The constants, however, are few: composition of the material, wall thickness of the pieces to be joined, heat dissipation properties of the material.

Joining the two takes an approach that is fine tuned by each operator, however the goal is the same; a cleanly welded joint that is solid through the root, creates a gentle transition between the two pieces without removing base material from the parent metal, and a gentle feathering of the filler on the edges.

Ideally, when welding thin walled bicycle tubing, the arc should be placed into the joint so as to create a keyhole, or an equal melting away from the joint's edges, that is then closed with the filler. As you travel forward, melting the material in front of your cooling puddle, your torch angle, distance from the joint, and rate of travel need to maintain consistency insuring you have full penetration, creating a solid/strong joint.

The master welders became so by learning two attributes; visually watching the changing elements of the keyhole/puddle and physically adjusting to maintain ideal conditions. This means that controlling heat input through the pedal, torch angle and distance, feed rate and travel speed, all becoming individual adjustments that factor into a cohesive whole.

The introduction of "pulsed" welding was intended to reduce overall heat input to the material, reducing HAZ and maintaining molecular stability. However, it was quickly adapted to creating a set of machine adjusted parameters that each operator found to be ideal for specific tasks. This is not to take away from the need to control the aforementioned elements, but it greatly reduced the need for on the fly changes, making it more efficient for the pro operator who is tasked with similar jobs frequently.

I have always been of the school of thought that I analyze the material properties I plan to join, set the machine amperage at the maximum I feel will be necessary for changing conditions (moving from varying wall thicknesses) and then use the pedal and individual physical adjustments to best react to the situation. This places the pedal most often in the middle of the travel range allowing for extended comfort and control, as the heat input can be increased or tapered off easily.

To create settings on the machine that mandates the pedal be "floored" for the majority of the pass takes away the ability to react, leaving only elements that have less effect, such as filler rate, to aid control.

Don't get me wrong, I'm not saying that this is wrong, incorrect, or not efficient. Only that it is an adoption of a new philosophy of welding, one that I feel is less controlled by the instincts of the operator.

As a beginner, you need to focus on learning to watch the physical reaction of the base metal and what it means. Examine how it changes with faster travel, more filler, varying torch angle, etc... Only after you achieve an understanding of how YOU affect the material can you then begin to examine settings on a machine that ease the process.

My two cents, for what it's worth.

Photo: I continue to get a lot of inquiries regarding welding technique, varying from the ubiquitous "what are your settings" to "I saw a guy once do...is this right?"  Sometimes these discussions occur in forum areas where I try to take a mentor-ship role in developing the knowledge and skills of those just dipping their toes into the trade.  Here is a snippet I pulled from one such post that gives some of my perspective on the differing techniques used by professionals today...

This is where I choose to have a differing perspective, and why fabrication has so many paths to the same end.

Multiple elements have an effect on the overall creation of the fused joint that can be controlled by the operator; amperage, filler size, filler feed rate, rate of travel, angle of torch, and cleanliness.

The constants, however, are few: composition of the material, wall thickness of the pieces to be joined, heat dissipation properties of the material.

Joining the two takes an approach that is fine tuned by each operator, however the goal is the same; a cleanly welded joint that is solid through the root, creates a gentle transition between the two pieces without removing base material from the parent metal, and a gentle feathering of the filler on the edges. 

Ideally, when welding thin walled bicycle tubing, the arc should be placed into the joint so as to create a keyhole, or an equal melting away from the joint's edges, that is then closed with the filler. As you travel forward, melting the material in front of your cooling puddle, your torch angle, distance from the joint, and rate of travel need to maintain consistency insuring you have full penetration, creating a solid/strong joint. 

The master welders became so by learning two attributes; visually watching the changing elements of the keyhole/puddle and physically adjusting to maintain ideal conditions. This means that controlling heat input through the pedal, torch angle and distance, feed rate and travel speed, all becoming individual adjustments that factor into a cohesive whole.

The introduction of "pulsed" welding was intended to reduce overall heat input to the material, reducing HAZ and maintaining molecular stability. However, it was quickly adapted to creating a set of machine adjusted parameters that each operator found to be ideal for specific tasks. This is not to take away from the need to control the aforementioned elements, but it greatly reduced the need for on the fly changes, making it more efficient for the pro operator who is tasked with similar jobs frequently.

I have always been of the school of thought that I analyze the material properties I plan to join, set the machine amperage at the maximum I feel will be necessary for changing conditions (moving from varying wall thicknesses) and then use the pedal and individual physical adjustments to best react to the situation. This places the pedal most often in the middle of the travel range allowing for extended comfort and control, as the heat input can be increased or tapered off easily.

To create settings on the machine that mandates the pedal be "floored" for the majority of the pass takes away the ability to react, leaving only elements that have less effect, such as filler rate, to aid control.

Don't get me wrong, I'm not saying that this is wrong, incorrect, or not efficient. Only that it is an adoption of a new philosophy of welding, one that I feel is less controlled by the instincts of the operator.

As a beginner, you need to focus on learning to watch the physical reaction of the base metal and what it means. Examine how it changes with faster travel, more filler, varying torch angle, etc... Only after you achieve an understanding of how YOU affect the material can you then begin to examine settings on a machine that ease the process.

My two cents, for what it's worth.

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