Micro TIG welding operates in the 1-50 amp range with tungsten electrodes as small as 0.020 inches in diameter, producing welds narrower than a human hair on parts you need magnification to see clearly. This is the process for jewelry repair, eyeglass frame mending, dental prosthetics, small instrument fabrication, and any work where the heat-affected zone needs to be measured in thousandths of an inch. Standard TIG machines can get down to 5-10 amps, but dedicated micro TIG units provide stable arcs below 5 amps with pulse frequencies up to 2,000 PPS that put heat exactly where you need it and nowhere else.
The skills are the same as full-size TIG: control the puddle, feed the filler, manage the heat. But the scale changes everything. You’re working under magnification, holding a torch with a tip smaller than a ballpoint pen, and manipulating filler wire thinner than a straight pin.
Micro TIG Machines
What Makes Them Different
Standard TIG welders are designed for 5-250+ amp range. Below 5 amps, most standard machines can’t maintain a stable arc. The arc wanders, starts and stops erratically, and the low-end resolution is too coarse for micro work.
Micro TIG machines are designed from the ground up for the 1-50 amp range:
- Precise low-amperage arc start: High-frequency or capacitor-discharge arc starts that don’t damage small parts
- Fine amperage adjustment: 0.1-amp increments at the low end
- High-frequency pulse: Up to 500-2,000+ PPS (pulses per second). High pulse frequency concentrates heat at the fusion point with minimal spread into surrounding material.
- Short arc times: Some units fire in millisecond bursts (10-100 ms per pulse), controlling total heat input per weld to fractions of a joule.
- Integrated microscope or camera: Some units include built-in optical systems for viewing the weld zone.
Machine Categories
| Category | Amp Range | Pulse Capability | Typical Cost | Applications |
|---|---|---|---|---|
| Micro-pulse welders (PUK, Orion) | 0.5-50A | Up to 2,000 PPS, ms-level pulse | $2,000-8,000 | Jewelry repair, dental, eyeglass frames |
| Dedicated micro TIG (Sunstone, Sparx) | 1-80A | Up to 500 PPS | $3,000-10,000 | Jewelry fabrication, instrument making |
| Standard TIG with pulse (low-end capable) | 5-200A | Up to 250 PPS (some higher) | $1,500-4,000 | General TIG + light micro work |
| Resistance micro welder | N/A (energy-based) | Single pulse, ms duration | $500-3,000 | Tack welds, battery tabs, small assemblies |
Choosing a Machine
For jewelry repair and fabrication, a dedicated micro-pulse unit (Orion, PUK, or equivalent) is the standard. These machines are designed specifically for precious metals and provide the millisecond-level pulse control needed for work on gold, silver, and platinum.
For small-part fabrication in steel and stainless (instruments, model engineering, micro brackets), a precision TIG with high-frequency pulse capability covers the range. Some standard TIG machines with pulse (Miller Dynasty, Lincoln Precision TIG) can work in this space if they have stable arc performance below 10 amps.
For occasional micro work alongside regular TIG, a standard pulse-capable TIG machine gets you started without a dedicated micro investment. You’ll be limited to about 5 amps minimum and lower pulse frequencies, but it handles many small-part applications.
Tungsten Selection for Micro Work
Electrode Sizes
| Tungsten Diameter | Amperage Range | Application |
|---|---|---|
| 0.020" (0.5 mm) | 1-10A | Finest jewelry work, eyeglass frames |
| 0.040" (1.0 mm) | 5-25A | General jewelry, small instrument parts |
| 1/16" (1.6 mm) | 10-50A | Larger micro work, thin sheet metal |
Electrode Types
2% lanthanated (blue band) is the standard for micro TIG. It maintains a sharp point at low amperage, starts easily, and carries low current without wandering.
2% ceriated (grey band) works well for very low amperage DC work. It has a slightly lower work function than lanthanated, meaning it emits electrons more easily at lower currents.
Pure tungsten (green band) is used with AC polarity on aluminum at micro scale. It balls naturally and provides a stable AC arc.
Sharpening Micro Tungsten
Standard tungsten grinding techniques scale down for micro work, but the precision required is higher.
0.040-inch and larger: Grind on a diamond wheel to a taper with a 15-20 degree included angle. The point should be sharp but not needle-like (too fragile). Grind lengthwise (parallel to the tungsten axis) for best arc stability.
0.020-inch: These are too small for most standard grinding setups. Dedicated micro tungsten sharpeners (small diamond wheels with precise guides) handle these diameters. Alternatively, sharpen by hand-rolling on a fine diamond lap. The taper should be gentle (20-30 degree included angle) to prevent the tip from breaking off during welding.
Stickout: Keep the tungsten extension from the cup short (2-3 mm) for micro work. Short stickout improves gas coverage and arc stability.
Magnification Systems
Stereo Microscope
The professional standard for jewelry and micro welding. A stereo microscope provides:
- True depth perception (critical for guiding filler wire to the joint)
- Adjustable magnification (typically 7-45x zoom)
- Long working distance (6-8 inches clearance for the TIG torch)
- LED ring illumination for shadow-free viewing
Important specification: Working distance. A microscope with 2 inches of clearance between the lens and the workpiece doesn’t leave room for a TIG torch. You need at least 6 inches (150 mm) of working distance. This limits maximum magnification but provides the access you need.
Magnifying Visor (OptiVisor)
Lower magnification (1.75-3.5x) but provides a wide field of view and hands-free operation. Good for general assembly and larger micro work. Not enough magnification for fine jewelry repair.
Digital Microscope Display
A USB or HDMI microscope camera displaying on a monitor. Provides high magnification without looking through eyepieces. Some welders prefer this because you can position the camera close to the work while keeping your head at a comfortable distance. The downside is a slight image lag on some systems, which makes real-time welding coordination harder.
Fixturing Small Parts
Holding tiny parts in position for welding is often harder than the welding itself. Standard clamps are too large and too heavy. Purpose-built micro fixturing tools include:
Third-Hand Tools
Articulated arms with alligator clips, cross-locking tweezers, or spring clamps that hold parts at adjustable angles. The base should be heavy enough (weighted base or magnetic base) that the arms don’t tip over.
Tweezers and Cross-Locking Forceps
Cross-locking tweezers clamp parts and stay closed without holding pressure. Available in fine-tip, flat-tip, and curved-tip configurations. These are the primary holding tools for jewelry and small parts.
Putty and Clay
Heat-resistant putty or investment casting material can hold irregular parts in a custom cradle. Press the part into the putty, remove it, and the putty retains the shape. Set the part back in for welding. The putty absorbs some heat and prevents the part from moving.
Jigs and Fixtures
For production runs of identical small parts, machine a fixture from aluminum or copper that holds the parts at the correct orientation. Copper fixtures also act as heat sinks, pulling heat away from the workpiece.
Micro Welding Techniques
Pulse Control
High-frequency pulse is the key technique for micro welding. Instead of a continuous arc, the machine fires rapid pulses:
- Peak amperage provides the heat to melt the base metal and filler
- Background amperage (near zero) lets the puddle solidify between pulses
- Frequency determines how many melt/solidify cycles occur per second
| Pulse Frequency | Effect | Application |
|---|---|---|
| 1-10 PPS | Visible individual pulses, distinctive ripple pattern | Decorative welds, controlled bead spacing |
| 10-100 PPS | Smoother bead, narrower HAZ than DC | General micro TIG, thin material |
| 100-500 PPS | Arc focuses tightly, very narrow HAZ | Jewelry repair, heat-sensitive parts |
| 500-2,000 PPS | Near-laser precision, minimal heat spread | Precious metals, eyeglass frames, dental work |
At high pulse frequencies (500+), the arc concentrates into a very tight column. The HAZ shrinks to fractions of a millimeter. Heat-sensitive components (stones in jewelry settings, thin wire frames, temperature-sensitive alloys) survive welding nearby because the heat doesn’t spread.
Filler Wire for Micro Work
Standard filler rods are too thick for micro welding. Use filler wire in the 0.010-0.030 inch diameter range:
| Base Metal | Filler Wire | Diameter | Notes |
|---|---|---|---|
| Stainless steel | ER308L | 0.020-0.030" | Match to base alloy (316L for 316) |
| Mild steel | ER70S-2 | 0.020-0.030" | Clean metal required at this scale |
| Titanium | ERTi-2 (CP Grade 2) | 0.020-0.030" | Full argon coverage, no air contamination |
| Gold (14K yellow) | 14K gold wire | 0.020-0.030" | Match karat and color to base |
| Silver (sterling) | Sterling silver wire | 0.020-0.030" | Argon flood required, oxidizes fast |
| Platinum | Pt950 wire | 0.020-0.030" | High melting point, stable in argon |
Cut filler wire into 2-3 inch lengths for handling. Longer pieces are unwieldy under magnification. Clean the filler wire with acetone or alcohol before use. Fingerprints and oxidation on a 0.020-inch wire represent a significant proportion of the wire’s mass.
Shielding Gas for Micro Work
Standard TIG uses a cup and gas flow from the torch. For micro work, additional gas coverage is often needed:
Argon flood chamber: A small enclosed or semi-enclosed box filled with argon. The workpiece sits inside the box, surrounded by argon on all sides. This prevents oxidation on reactive metals (titanium, silver) and provides consistent shielding independent of torch position. Simple versions are a clear acrylic box with arm holes and an argon inlet.
Trailing shield: An attachment behind the TIG cup that extends argon coverage over the hot weld as the torch moves. Prevents oxidation on the cooling weld zone.
Increased flow rate: Even without a chamber, increasing argon flow to 25-30 CFH and using a large gas lens cup (#10-#12) provides better coverage than standard settings for micro work.
Applications
Jewelry Repair
The most common micro welding application. Prong re-tipping, ring sizing, chain repair, setting repair, and filling porosity in castings. The advantage of micro TIG over traditional jewelry torch work (oxy-hydrogen or oxy-propane) is precision: you can weld next to a heat-sensitive stone without heating the entire piece.
Eyeglass Frame Repair
Titanium and stainless steel frames crack at the bridge and hinge points. Micro TIG with matching filler repairs these cracks without visible distortion. The frame needs to be clean and the broken ends aligned precisely before welding.
Dental Prosthetics
Cobalt-chromium and titanium dental frameworks are assembled and repaired by micro TIG welding. This is a specialized field with its own certification requirements.
Instrument and Device Fabrication
Small stainless steel components for medical instruments, electronic housings, and precision mechanisms are assembled with micro TIG. The welds must be smooth, consistent, and free of contamination.
Model Engineering
Scale model steam engines, locomotives, and mechanical devices are fabricated from thin-wall tubing and sheet. Micro TIG assembles components that are too small and thin for standard welding processes.
Heat Management at Micro Scale
The primary challenge in micro welding is controlling heat spread. A weld that works perfectly on 1/4-inch plate will melt a 0.020-inch wire into a blob. Strategies:
Minimum amperage. Start at the lowest setting that produces an arc and increase only as needed.
Copper heat sinks. Clamp copper close to the weld zone. Copper conducts heat away from the part faster than the part can absorb it.
Tack-and-wait. Place one tack, let the part cool completely (30-60 seconds on small parts), then place the next tack. Trying to run a continuous bead on a tiny part overheats it instantly.
Pulse mode. Use the highest pulse frequency your machine supports. Each pulse delivers heat for milliseconds, and the cooling interval between pulses prevents heat accumulation.
Mass balance. If you’re welding a thin wire to a thick base, the thick base sinks heat and the thin wire melts too fast. Direct the arc slightly toward the thicker member to balance the heat distribution.
Common Micro Welding Mistakes
Too much heat. The number-one issue. Starting at 20 amps on a piece that needs 3 amps melts the part before you see the puddle form. Start low and increase in 1-amp increments.
Poor fixturing. Parts that shift during welding produce offset joints and burned-through connections. Invest time in holding the parts rigidly in exactly the right position before starting the arc.
Dirty filler wire. At micro scale, surface contamination on the filler wire represents a significant proportion of the material being deposited. Oil or oxide on a 0.020-inch wire creates porosity and poor fusion in a micro weld.
Inadequate shielding. Reactive metals (titanium, silver) need complete argon coverage. A standard cup and 15 CFH flow rate might work for steel but leaves titanium oxidized and brittle. Use a flood chamber for reactive metals.
Wrong magnification. Trying to micro weld without adequate magnification means you can’t see the joint, the puddle, or defects. If you can’t see it, you can’t weld it.
Micro TIG welding is standard TIG technique scaled down to the limits of human hand control and visual acuity. The process is the same. The precision required is an order of magnitude higher. Practice on scrap material at the scale you’ll be working at before committing to a customer’s jewelry or a production part.
For related topics, see the artistic metalwork overview and our guide to decorative ironwork welding.