A welding contact tip forms the point of contact between the welding gun and the welding wire. It is typically made of a durable and conductive material, often copper or alloys with high thermal conductivity.
It is an important consumable of mig welder torch and it helps transfer current from conductor tube (gooseneck or swan neck) to the nozzle of the gun through wire inside the torch. Gun nozzle is connected to the tip at one edge and touches the workpiece and creates an arc.
Choosing a correct contact tip is a must for producing the best welding result. Because a right size contact tip may prevent issues like micro arcing, overheating, friction and wire jamming which in turn leads to wire burn back and premature contact tip failure.
Functions of Contact Tips
The functions of contact tips are as follows-
- Electrical Conductivity: The primary function of the contact tip is to provide a low-resistance electrical path for the welding current to pass from the welding gun through the welding wire to the workpiece. This in turn facilitates the creation of an electric arc at the edge of the welding point.
- Guiding and Feeding: The contact tip helps guide the welding wire from the wire spool or wire drive to the weld pool via welding gun. It also assists in maintaining a consistent and stable wire feed during the welding process.
- Heat Dissipation: The contact tip plays a role in dissipating heat generated during welding. Efficient heat dissipation is essential to prevent the contact tip from overheating, deforming, or prematurely wearing out.
Benefits of Using high quality tips
- Improved Weld Quality: High-quality silver plated contact tips contribute to better welding by ensuring a consistent and stable electrical connection. This helps minimize the risk of erratic arcs, spatter, and other welding defects.
- Extended Tip Life: Quality materials and construction enhance the durability of high-quality contact tips. They resist wear and deformation, leading to a longer lifespan compared to lower-quality alternatives. This can result in cost savings over time as replacement frequency is reduced.
- Reduced Downtime: Using a high-quality contact tip can contribute to increased productivity by minimizing the need for frequent tip changes. Reduced downtime translates to more efficient welding operations.
- Optimized Wire Feeding: A well-designed contact tip promotes smooth and reliable wire feeding. This is crucial for maintaining consistent arc stability, preventing wire jams, and ensuring uniform weld bead deposition.
- Enhanced Heat Resistance: High-quality contact tips are often designed to withstand higher temperatures associated with heavy-duty or prolonged welding applications. This heat resistance prevents premature failure and maintains tip integrity under challenging conditions.
- Compatibility with Various Materials: Some high-quality tips are engineered to be versatile and compatible with a range of welding materials, including different wire types and thicknesses.
What materials are used to make contact tips
The most common materials used for manufacturing contact tips include:
- Copper: Copper is one of the most widely used materials for contact tips with excellent electrical conductivity. Copper tips are also known for their good heat dissipation properties. Copper is highly conductive, it may wear more quickly than some other materials, leading to the need for periodic replacement.
- Copper Alloys: Alloys such as copper-chromium, copper-zirconium, or copper-nickel may be used to improve wear resistance, increase heat tolerance, and extend the lifespan.
- Beryllium Copper: Beryllium copper is a specialized alloy that includes a small percentage of beryllium. This alloy offers high strength, excellent electrical conductivity, and improved heat resistance.
- Tungsten: In some specialized applications, contact tips made from tungsten or tungsten alloys are used. Tungsten exhibits high melting points and is resistant to thermal wear, making it suitable for high-temperature welding processes. The tungsten contact tip life is higher than other material tips.
- Brass: While less common than copper or copper alloys, brass is occasionally used for contact tips. Brass is an alloy of copper and zinc and provides good electrical conductivity.
- Silver Plating: Some contact tips may have a silver-plated surface. Silver plating enhances electric conductivity and improves resistance to corrosion.
Factors affecting contact tip performance
The following factors affect the performances of mig welding contact tips.
1. Gas diffuser
The gas diffuser is a component located within the welding gun assembly that helps distribute the shielding gas evenly around the welding wire as it exits the contact tip.
Proper gas diffusion is crucial for effective shielding of the weld pool, preventing oxidation, and minimizing spatter. A damaged or poorly functioning gas diffuser can lead to uneven gas distribution, affecting consistent weld quality and increasing the likelihood of contact tip and nozzle issues.
2. Contact tip size
Wire size and filler metal requirement depend on contact tip size. Tip begins to lose conductivity and in turn reduces electric current flow to the wire as it wears off. This condition leads to unusual arcs, lower penetration and bad quality weld. You need to replace the tip frequently if in this case and it’s due to the wrong selection of tip size.
Normally tips range from 0.24″ to 0.95″. Larger wire causes higher deposition rate wearing the tip and wire quickly. Smaller tip doesn’t fit the goose neck and diffuser leading to disrupted weld. So the contact tip should match the wire size for better weld.
3. Connection between wire & contact tip
The point of contact between the welding wire and the contact tip is critical for electrical conductivity profile and wire feeding. Several factors influence this contact.
For example- Alignment, Cleanliness, Tension & Wire Condition. Without aligned and clean connection, inconsistent current flow would cause issues.
4. Weld wire quality
The type of welding wire can affect contact tip performance. Different wires may require specific tip designs to ensure proper feeding and arc stability.
Using high quality wire either flux core or solid, enhances the capability of contact tip and in turn helps creating high quality weld.
5. Material Compatibility
Choosing the right material contact tip for the specific welding application is essential for optimal performance. Copper and its alloys are commonly used due to their superior conductivity and heat dissipation properties.
6. Welding Conditions
Parameters such as voltage, current, and shielding gas influence contact tip performance. Variations in these conditions can affect the heat generated at the tip and impact its wear rate.
7. Contact Tip Recess
Contact tip position inside the gas nozzle also called as contact tip Recess impacts the high quality welding performance. Proper alignment reduces the chance of spatter & porosity in weld puddles. Also it reduces the birdnesting, burn-back and warping problems while mig welding.
Recess measurement varies between 1/4″ to 1/8″ out.
1/4″ and 1/8″ recess is beneficial for Mig welding using 100% argon gas in spray transfer mode at 200 amp current input.
For lower argon proportion or 100% co2 gas, flush recess is good. And for hard to reach welding areas, 1/8″ recess of contact tip is best.
If the tip is recessed more, it will stick out more. For shorter stick-out and recess, lower voltage will be used.
Common issues with contact tips
Few issues can appear if the wrong size contact tip is chosen or low quality tip is fitted to the mig gun. They are-
- Burnback
- Premature MIG Contact Tip Failure
- Micro-arcing
- Overheating
- Friction
- Wire jam
Checkout the guide on common contact tips issues and solutions for more detailed information.
Advice To Prevent Common Contact Tips Problems
After you match the contact tip to the wire size and fit that to the torch, it is necessary to follow some advice to get the most out of the tip.
- Cool down the torch before replacing the contact tip. Changing contact tips while the gun is still hot can be challenging and also there is a chance of ruining the new contact tip by cross-threaded the tip.
- Using longer contact tip ruins the weld quality and also using undersized tip causes friction and jamming of wire into the gun. Both create problems that lead to poor weld. So the correct size should be chosen first.
- If you don’t tighten the contact tip a few issues arise like micro-arc & overheat. That leads to erratic wire feed & burnback into the tip.
- Regularly monitor the appearance of contact tips. If it appears blue or purple, it means the connection is not correct. Also it can be the sign that the consumables are too big or your gun amperage has exceeded the required limit. If you see the issue, troubleshoot the gun and fix them.
Lastly
Understanding and managing contact tips increase the welding performance, resulting in improved weld quality, reduced downtime, and increased efficiency in MIG welding processes.
Regular inspection, proper maintenance, and adherence to recommended welding practices contribute to achieving consistent and reliable contact tip performance.
Related Articles
Sources
- americantorchtip.com/blog/everything-you-need-to-know-about-mig-contact-tips/
- tregaskiss.com/tips-for-choosing-the-right-contact-tip/