What Are Stickout, Electrode Extension and Contact-Tip-To-Work Distance?

Stickout and electrode extension are often used interchangeably. Learn more about the difference and how it impacts weld quality.

Understanding welding terms

Producing quality welds requires attention to detail in setting weld parameters. Even slight changes can lead to significantly different results.

Achieving the right parameters to get the results you want requires understanding and using proper welding terms. Here’s an example I see frequently across the industry: People often use electrode extension, stickout and contact-tip-to-work distance interchangeably.

But these terms measure different things, and using them interchangeably — or not understanding their proper meanings — can cause confusion that alters weld parameters and, ultimately, weld quality.

So, how do electrode extension, stickout and contact-tip-to-work distance differ? Let’s talk about each one and why it’s important to use the proper term.

Understanding the difference

Changing the distance between your welding gun and the workpiece affects the amount of resistance in the welding circuit, and a change to the resistance also alters amperage in a constant voltage process like gas metal arc welding (GMAW). To help ensure and maintain proper amperage in your application, it’s important to know the meaning of these common terms and how they differ:

• Electrode extension: As defined by the American Welding Society (AWS), this refers to the length from the end of the contact tip to where the wire melts off.
• Stickout: Another common term defined by the AWS, this refers to the end of the nozzle to where the wire melts off. The only time that electrode extension and stickout can be used interchangeably is when the contact tip is flush with the end of the nozzle. In instances where the contact tip is recessed, these two terms refer to different distances.
• Contact-tip-to-work distance: While this is a commonly used industry term — even in many weld procedures — it’s not actually defined by AWS A3.0 Standard terms and definitions. The best time to measure contact-tip-to-work distance is when you’re preparing the weld or programming the robot, and you can take a physical measurement before you strike the arc. Once the arc is struck, arc length is measured by voltage, and electrode extension can be measured by resistance in the circuit or with sight. When people use the term contact-tip-to-work distance, they often mean the sum of arc length and electrode extension.

How it affects amperage

Maintaining consistent electrode extension during welding is critical because varying the extension can change your amperage, which can put you out of range of your welding specifications. When that happens, you may be depositing a weld that’s less than sound.

Too short of an electrode extension increases the amperage and brings you closer to the weld pool, which can cause premature damage to the contact tip and create burn-through from too much heat. Too much extension lowers the amperage and can result in poor penetration that requires rework.

Consider this example of GMAW in spray transfer mode using the same wire type, shielding gas, base metal and nozzle diameter in both instances. The original contact-tip-to-work distance was 19mm, resulting in 235 amperes. With nothing else changing except the contact-tip-to-work distance, simply changing that from 16mm to 25mm causes amperage to operate in a window from 282 to 213 — which could put you out of spec for the application.

This happens because increasing the distance causes an increase in resistance — and the amount of resistance in the welding circuit can make or break your weld quality. To see just how much even small changes to this distance can affect amperage, you can play around with changing the electrode extension in your noncritical welding applications.

Improve weld quality

Contact-tip-to-work distance is often the most logical term to use in welding applications. But it’s important to know that electrode extension, stickout and contact-tip-to-work distance all have specific definitions, and using them interchangeably can cause confusion that puts amperage out of the specified range.

It’s especially important to use the right industry standard terms when communicating globally about welding applications — to help ensure that all parties are on the same page.

The bottom line: Understanding the terms being used provides clarity that can help prevent mistakes and rework.

High strength steels continue to be popular for fabrication and manufacturing applications that require materials with less weight and thinner sections — without sacrificing strength. These include the building of cranes, Offshore Jack-up legs, heavy equipment, pressure vessels, bridges and more.

As with any material, high strength steels require special attention when it comes to welding. To help, here are answers to some frequently asked questions about the material and the process of welding it.

In addition to understanding the challenges of welding high strength steel and knowing the filler metal options for the job, it’s important to maintain awareness about controlling heat.

What is high strength steel?

High strength steel gains its strength from specific alloying elements, including manganese and nickel, as well as molybdenum and chromium, in some cases. This material has both high tensile and high yield strengths. Tensile strength refers to the amount of force required to bend the material until it breaks. Yield strength is the amount of force necessary to deform or bend the steel. Having higher levels of strength means that there is less chance of high strength materials breaking or deforming. Often this material is formulated according to industry standards and classified as EN, ASTM, ABS or AISI, but there are proprietary manufacturing processes too. For any formulation of high strength steel, it’s important to use a filler metal with the appropriate chemical and mechanical properties, especially since this material is designed to carry more and withstand more extreme service conditions.

What are the challenges of welding high strength steel?

Since high strength steel is often used in thinner sections, it reduces weight for the given application. However, it also can cause the material to shrink during the welding process, resulting in residual stress in the weld joint and greater risk of distortion. If the application requires multiple passes, placing smaller weld beads can help keep the heat input lower and reduce distortion. Keeping heat low also lessens the risk of weakening the material.

Cracking can also be an issue when welding high strength steel. For that reason, it’s important to control the amount of hydrogen being introduced into the weld. Low hydrogen filler metals are one line of defense. Controlling the cooling rate of the weld and material through proper preheat and the monitoring of interpass temperatures can also help reduce the opportunity for cracking.

What filler metals are best for the job?

Unlike more common materials like mild or carbon steel, there are fewer filler metal options for welding high strength steels. But like all materials, matching the mechanical strength of the filler metal with the high strength steel is key to maintaining weld integrity.

Low alloy metal-cored wires and low alloy gas-shielded flux-cored wires provide high tensile and yield strengths for welding high strength steels. The ELGA Filler Metals also contain low levels of hydrogen and carry a specific designator to indicate that. For example, an H4 designator according to AWS means that the wire has less than 4 milliliters of diffusible hydrogen per 100 grams of weldment.

High strength steels continue to be popular for fabrication and manufacturing applications that require materials with less weight and thinner sections — without sacrificing strength. These include Cranes, heavy equipment, Offshore Jack up legs, etc.

ELGA offers a wide range of products for welding S690 or S890 grades. Metal-cored wires like MEGAFIL® 742 M or MEGAFIL® 1100 M are good choices for welding high strength steels. In the right application, they can offer higher deposition rates and travel speeds than other wires, leading to increased productivity. The ELGA High Strength Steels metal-cored wires also provide excellent toughness properties and very low hydrogen levels.

Options for welding high strength steel include gas-shielded flux-cored wires with either a Rutile (T-1) or Basic (T-5) slag system. All positional rutile (T-1) wires like MEGAFIL® 690 R offer good weldability and a stable arc; however, they tend to have slightly less ductility and toughness than Basic (T-5) wires. Conversely, wires with a basic slag system like MEGAFIL® 742 B offer good mechanical properties and strength, as well as low diffusible hydrogen levels. Unfortunately, Basic wires aren’t as operator friendly as Rutile wires and often generate more spatter. Depending on the application, these pros and cons will need to be weighed against one another. Like any other flux-cored wires, these wires require slag removal after welding or between passes.

Final thoughts

Preheating helps slow the cooling rate by keeping the temperature at the right level during welding, reducing cracking opportunity and helping the material regain toughness in and around the weld joint as it cools. Always check temperatures between passes to ensure they are in the proper range.

Adequate Cooling rate is key to obtain the required tensile strength and toughness and keep the hardness at the right level. Feel free to contact your ELGA representative for additional advice.