Welding is an essential skill in metal fabrication, and choosing the right process can impact the quality, efficiency, and strength of your welds. MIG and TIG welding are two of the most common welding techniques, each with its own strengths and applications. If you’re looking to switch from MIG to TIG, properly setting up your welding machine is crucial for achieving clean, high-quality welds.
This guide walks you through the key steps of transitioning from MIG to TIG welding, including adjusting your machine, selecting the right consumables, and optimising settings for the best results.
- MIG Welding (Gas Metal Arc Welding – GMAW): Uses a continuously fed mig wire and shielding gas, making it ideal for fast, high-productivity welding on thick materials.
- TIG Welding (Gas Tungsten Arc Welding – GTAW): Uses a tungsten electrode to create an arc while the welder manually feeds a filler rod, allowing for precise, high-quality welds, particularly on thin metals and non-ferrous materials like aluminium.
Step 1: Prepare Your Welding Machine
Most modern welding machines can handle both MIG and TIG processes with the appropriate settings and accessories. Follow these steps to switch your machine over:
1. Change the Polarity
MIG welding typically uses DC Electrode Positive (DCEP), while TIG welding uses DC Electrode Negative (DCEN) for most applications.
- Locate the polarity terminals on your machine.
- Switch from DCEP (MIG setting) to DCEN (TIG setting) by adjusting the leads.
- If you’re welding aluminium with TIG, switch your machine to AC (Alternating Current) mode.
2. Swap Out the MIG Torch for a TIG Torch
MIG welding uses a gun with a trigger and a continuously fed wire, while TIG welding requires a hand-held torch with a tungsten electrode.
3. Adjust the Gas Supply
Shielding gas is essential in both MIG and TIG welding, but the gases used differ:
- MIG welding often uses CO₂ or a mix of Argon and CO₂.
- TIG welding requires 100% Argon for most applications.
To switch:
- Disconnect your MIG gas supply.
- Connect a pure Argon gas cylinder to your regulator.
- Set your flow rate between 7-12 Liters per minute) for most TIG welding applications.
Step 2: Select the Correct Tungsten Electrode
- For steel and stainless steel: Use 2% Thoriated (Red) or 2% Lanthanated (Blue) tungsten.
- For aluminium: Use Pure (Green) or Zirconiated (White) tungsten and switch your machine to AC mode.
Step 3: Adjust Your Machine Settings
TIG welding requires voltage and amperage settings that are different from those of MIG. The exact settings depend on material type and thickness:
1. Amperage Settings
- Thin materials (1-2mm): 30-80A
- Medium thickness (3-5mm): 80-150A
- Thicker materials (6mm+): 150-250A
2. Pulse Settings (Optional)
If your machine has pulse TIG functionality, you can fine-tune the heat input to reduce distortion, particularly for thin materials.
- Pulse Frequency: 1-5 Hz for basic control, up to 100 Hz for advanced applications.
- Pulse Width: 30-50% for general welding.
3. Post-Flow Gas Timer
TIG welding requires a post-flow setting to protect the weld and tungsten from oxidation:
- Set post-flow between 5-10 seconds depending on amperage.
Step 4: Practice Your Technique
TIG welding requires more precision than MIG. Unlike MIG welding, where the filler metal is fed automatically, TIG welders must manually control the filler rod while maintaining a steady arc.
- Hold the TIG torch at a 10-15 degree angle from the workpiece.
- Maintain a short arc length (1-2mm) for best control.
- Use foot pedal or hand controls to regulate heat input dynamically.
Common Mistakes to Avoid When Switching to TIG
- Using the Wrong Gas: Make sure you switch to 100% Argon instead of CO₂ or mixed gases used in MIG.
- Forgetting to Change Polarity: MIG uses DCEP, while TIG (except aluminium) requires DCEN.
- Not Sharpening the Tungsten Properly: A blunt or contaminated tungsten tip can cause unstable arcs and poor weld quality.
- Neglecting Post-Flow Gas: Stopping the gas too soon can lead to oxidation and weak welds.
- Rushing the Weld: TIG welding requires slow, steady hand movements to control heat and filler deposition.
Conclusion
Switching from MIG to TIG welding requires careful adjustments to your machine, shielding gas, and technique. While TIG welding demands more precision, it produces cleaner, higher-quality welds, making it ideal for thin materials, stainless steel, and aluminium.
By following this step-by-step guide, you’ll be well on your way to mastering TIG welding and expanding your welding capabilities. Whether you’re a fabricator, mechanic, or hobbyist, taking the time to properly set up your machine will ensure better weld quality and a smoother transition between processes.
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