Tag: porosity fix

Intro

Your MIG welds look porous. You’ve checked your gas flow, cleaned the base metal, and verified your settings—but the problem persists. The culprit is often sitting right at the end of your gun: a worn contact tip. A damaged or burnt-back contact tip disrupts the electrical arc and wire feed, creating weak welds and wasted material. This guide walks you through diagnosis and replacement in under 10 minutes.

Key Takeaways

• Worn contact tips cause porosity, spatter, and inconsistent arc
• Burnback happens when the tip overheats from improper voltage/wire speed ratio or poor contact
• Replace tips every 50–100 hours of welding or when you see damage
• Always match wire size to tip size (e.g., .035″ wire = .035″ tip)
• Stock replacement tips on hand to avoid downtime

The Problem

A contact tip is a small copper tube that carries current to your wire. Over time, it erodes from heat and electrical wear. When the tip is damaged or burnt back, several things go wrong:

• Poor electrical contact: The wire doesn’t seat properly, creating resistance and weak arc initiation.
• Inconsistent wire feed: A damaged tip can catch or bind the wire, causing feed stutters.
• Arc instability: The arc becomes erratic, leading to porosity and spatter.
• Weld quality drops: Porosity, lack of fusion, and surface defects become common.

You’ll notice:

• Spatter clustering around the weld
• Dull, unstable arc
• Wire feed hesitation or grinding sounds
• Visible burnback or erosion on the tip itself

Why It Matters

A bad weld costs money. Porosity weakens the joint, spatter wastes time cleaning, and rework eats into your schedule. In structural or pressure-vessel work, porosity can fail inspection. Replacing a $2–5 contact tip takes 2 minutes and prevents hours of rework.

The Fix

1. Power down the welder and wait 30 seconds.
2. Unscrew the contact tip from the gun nozzle (usually hand-tight or one-quarter turn with a wrench).
3. Inspect the old tip for burnback, erosion, or debris.
4. Clean the gun nozzle with a wire brush to remove spatter buildup.
5. Install the new tip, hand-tight. Don’t over-tighten.
6. Test the wire feed before welding—pull the trigger briefly to confirm smooth feed.
7. Strike a test bead on scrap to verify arc stability.

Why This Product Solves It

The S19391-1 Lincoln Style Contact Tip .035 – Arc Weld by Masterweld Pack of (25) is a direct replacement for Lincoln-style MIG guns. It’s made from high-quality copper, ensuring reliable electrical conductivity and durability. At .035″ bore, it matches the most common MIG wire size. A pack of 25 means you’ll always have spares on hand, eliminating downtime from tip searches.

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