If a MIG welding gun is fitted with the best parts for the job, the result is a high-quality, sturdy weld that’s completed with little downtime to fix your rig. But that’s a big IF, because figuring out what those parts are feel like a puzzle where all the pieces look the same.
One of the most important pieces in a MIG gun setup is the contact tip — it’s what transfers the current to the wire in order to create the arc. But like other consumables, contact tips are available in a range of materials, sizes, and other specs, and choosing the right tip for your application can mean the difference between an efficient job and one beset by problems.
Welding gun contact tips are made using several types of materials. Here’s a breakdown of the types, the pros and cons, pricing, and best applications for each.
Copper Contact Tips (E-Cu)
- Conductivity: 55 S/m
- Max Temperature: 500º F
Copper is considered a standard metal for contact-tip construction due to its excellent conductivity (it’s the second most conductive metal behind silver) and its ability to withstand the high heat generated by the welding process. Most often, copper tips are recommended for hand-welding applications, especially when the wire targeting doesn’t need to be precise.
On the downside, because copper has a lower softening point, it’s prone to wear out faster than some of its harder counterparts. As the temperature goes up, the copper contact tip can actually get softer than the feed wire. This can cause a host of problems including decreased conductivity, arc-start problems, contact tip burnback and bad welds, among others.
Because they’re considered general purpose, copper contact tips are generally the most affordable choice, which means quicker wear might be an even trade-off for more frequent replacements.
Copper-Chrome-Zirconium Contact Tips (CuCzZr)
- Conductivity: 50 S/m
- Max Temperature: 932º F
This copper alloy contact tip is often the consumable of choice for robotic welding applications for a few reasons, including its hardness relative to copper and resistance to long welding cycles. It’s also a better choice when the Tool Center Point (TCP) requires precision. Although it’s a bit less conductive than copper alone, it’s still a good choice for jobs that use stainless steel as a base metal or flux-core or metal-cored wires.
The softening point for CuCzZr is almost double that of copper, which means much better productivity and life. Unfortunately, it can also mean double the price tag.
Silver-Plated Contact Tip (CuCzZr)
- Conductivity: 62.1 S/m
- Max Temperature: TBD-1,472º F
Silver is the one metal that’s more conductive than copper. It’s also 17 percent denser and has a higher softening point. When applied to a CuCzZr contact tip, the silver plating creates a solid combo of hardness and conductivity. As a result, it can reflect more heat, reduce spatter and slow down wear and tear.
RELATED: 5 Causes of Contact Tip Burnback
In fact, a silver-plated tip can last up to nine times longer than a standard copper tip, which makes productivity one of its best features. They can also help reduce micro-arcing, improve arc-starts and provide consistent quality. But with that extra productivity comes extra price — up to 50% more than the cost of a non-plated CuCzZr tip.
If you want to kick it up even another notch, silver-plated contact tips are also available in a heavy-duty version that can withstand heat up to 1,472 degrees. That makes them one of the only choices for extremely high-amp, long cycle robotic applications.
Contact Tip Recess and Stick-Out
Weld quality and productivity can also be affected by the contact tip recess, which is its position inside the nozzle. When it’s aligned correctly, it can reduce spatter and porosity in the weld puddle, as well as burnthrough or warping on thinner materials.
Contact tips typically come in one of four recess measurements, ranging from ¼-inch in to ⅛ -inch out.
- ¼ inch and ⅛ inch recesses are best for argon-rich mixed gas, spray transfer, and metal-cored wire, on jobs less than 200 amps
- A flush recess (meaning even with the exterior) is a good choice if you’re using gas with a low argon concentration, or 100% CO2 gas.
- A ⅛ inch extension is best for hard-to-reach joints.
The more the tip is recessed, the more the wire sticks out. And a good rule of thumb is to use the shortest wire stickout possible for the job. The shorter you can make your recess and stickout, the less voltage and stability you’ll have.
Welding contact tip sizes
Ideally, you’ll use a contact time that lets the feed wire move through it with minimal resistance yet maintaining electrical contact. In most cases, that means using a contact tip size that matches the size of the wire. You’ll see two separate measurements for the tip size. Outside diameters can range from 6 to 10 mm and the inside (bore) diameter ranges between 0.7 and 3 mm.
A contact tip that’s slightly smaller than the wire — especially if the wire is drum-fed or solid — can exert more pressure on the wire and hold it in place. This technique can increase your electric conductivity, but it can also cause problems like micro-arcing, erratic wire feeding, birdnesting, and others.
In the same vein, a contact tip that’s too large can lead to lower conductivity and higher temperatures. Both situations can lead to burnback.
Drawn Vs. Drilled Contact Tips
Equally as important as the exterior is whether the inside is drawn or drilled. Contact tips are usually made with a mandrel that heats the metal and draws it out into the correct shape. But copper doesn’t settle smoothly when it cools, which means the inside could contain high points. And those are like kryptonite to feed wire.
Drilled tips have one extra step in the manufacturing process — running a high-speed, cold drill through the bore. It creates a much smoother surface and gets rid of any high points. As a result, the quality of a drilled contact tip can be extremely better than one that’s drawn. It can also last 2 to 3 times longer, and the best part? The drilled interior doesn’t add to the price.
Quantity vs. Quality
Since a contact tip will eventually wear out no matter how it’s made, your instinct may be to gravitate toward the more affordable, general-use copper tips. However, it’s important to ask yourself whether a cheaper price up front will offset the cost of more frequent replacement and the potential downtime that comes with it.
Higher-priced contact tips, on the other hand, are made with greater precision and tighter tolerances, both of which lead to a better connection with the wire. So paying more in the beginning, could save you in the long run.
View our complete line of MIG welding contact tips to find exactly the right part for your job.