Best Practices for Welding Contact Tips & Nozzles


A lot of time and money will be spent on contact tips and nozzles so it is important to look at how to bring the most value to this process. This article will help to bring a deeper knowledge on welding contact tips and nozzles. 

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Contact Tips         

Contact tips are responsible for guiding the wire and transferring the current from the conductur tube (aka swanneck) through the filler wire and to the workpiece. They are in charge of the current transfer and wire targeting. 

Understanding how to keep your contact tip performing at its best is critical for your welding application needs. 

The material chosen for the contact tip is important because a torch consumable is the last line of conductivity in the welding circuit between the part. This means choosing the right material for your production line needs will provide a higher quality weld product.

The popular materials to choose from are copper, beryllium, copper zirconium, silver plated, and heavy-duty silver.

Beryllium copper: beneficial characteristics including durability, but it is considered to be toxic as a consumable to produce so engineers shy away from using it.

Copper: great conductivity, but lacks hardness, better arc characteristics leading to better weld quality and less touch-ups or rework. However, you will change a pure copper tip far more frequently than copper zirconium. Increased downtime and less throughput on the welding cell.

Copper Zirconium: greater hardness but less conductive.

Silver-plated contact tips: Uses a micron silver plating as it is very hard and conductive. This can increase the contact life 9 times compared to a standard copper tip. It has a lower spatter adhesion and a smoother bore as a result of the drilling process, creating a better heat and current transference.

BINZEL’s contact tips have the following as a point of reference:

weld_torch_contact_tips_hardness.png#asset:88392Picture Credit: The Definitive Guide to Robotic Welding Torches by Abicor Binzel

Deciding Between Drawn vs. Drilled Contact Tips

Drawn: is a common process for creating contact tips; there is more variation and less tolerance control. Copper is drawn and extruded from a long copper bar and then cooled into the contact tip. This is less expensive because the drilling step is removed from the production process.

Drilled: The bore is indexed, drilled, and machined from a solid shape which gives the orfice greater integrity. Extruded contact tips don’t last as long as drilled tips.

Differences between Drawn and Drilled:

The integrity and repeatability of the contact tip size is the true difference between drawn and drilled contact tips.

For instance, a 0.045’ contact tip made from a drawn process is more prone to errors in both bore size and finish. The wire, which always has a cast on it, is only hitting the high points of the tip finish so it’s typically going to wear on one side.

Also, the drawn process is not as reliably repeatable or precise as the drilled process. Margins of error exist in the tip bore as an .045” contact tip bore may be as large as .049” or as small as .042”.

This inconsistency can lead to low quality arc starts, rework, and decreased throughput. It can also lead to wire flip where the wire wanders outside the weld joint entirely causing scrap in the part because of inconsistent tolerances.

Nozzles

One of the most common issues with nozzles is the spatter buildup. A poor nozzle will incur great amounts of spatter build-up in a short amount of time. See below.

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Picture Credit: The Definitive Guide to Robotic Welding Torches by Abicor Binzel

Material selection is also imperative when choosing the correct nozzles; the more the material resists heat, the less spatter builds up in side the nozzle. See below. 

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Picture Credit: The Definitive Guide to Robotic Welding Torches by Abicor Binzel

For instance, pure copper or brass based material with the welding nozzle with not last as long as a harder plated nozzle material like a nickel or chrome plated nozzle because of their spatter and heat resistant properties (compare first picture of a brass nozzle above to the second picture).

Typically, you will find a harder conductive material that protects against spatter and suffers less scaling such as nickel. This will offer less ream cycles and ultimately greater productivity.

Slip-On Versus Threaded Nozzles

There are two kinds of nozzles: slip-on and threaded. The cost benefit analysis typically comes to downtime as it costs money, sacrifices throughput, and keeps the robot from achieving Return on Investment (ROI).

Slip-on: slip-on nozzles are believed to be easier to get on and off however they may loosen over time and cause porosity in the weld. They are also not effective for torch reaming.

Threaded: The risk is minimized to nonexistent. There is a fine thread option and a coarse thread option. Both styles offer more advantages to slip-on nozzles because they are less likely to fail.

Fine threaded nozzles are more difficult to install and remove (binding) while also having have a more difficult time dealing with debris and spatter.

Coarse threaded nozzles don’t’ have much impact from spatter and debris.

Contact RobotWorx Today!

In summary, it is important to understand the following: are you using drawn or drilled contact tips? What is the hardness and conductivity levels for contact tips? What is the tip material and how often changing contact tips? nozzle material? Are the nozzles threaded or slip-on? How often are the nozzles needing to be changed and what is the cost?

For more information on welding tips or nozzles, contact RobotWorx experts online or at 740-251-4312.

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