Hanlon Stud Welding Guide: CD vs Arc Studs, Setup & Safety

Quick Note: Hanlon’s own site notes that stud welding equipment can be serviced under its stud welding support program, and the supplier also carries the accessories side of the trade. Sourcing a machine and sourcing the ferrules that keep it running are two different conversations, and a good supplier handles both.

Hanlon’s own process comparison notes, this process can weld up to 3/8 inch diameter fasteners at rates of up to 20 welds per minute off of only 110 volt power, even when joining dissimilar metals.

There are two common ignition styles for CD:

• Tip ignition: Best for studs roughly M3 through M10. It’s fast and leaves little to no tip residue.
• Gap or lift ignition: Best for studs roughly 2 to 10 mm. It creates the arc across a lifted gap and is a little more forgiving on dirtier surfaces.

Drawn Arc: Built for Structural Loads

When a weld needs to carry real structural load, drawn arc is the go-to process. Unlike CD, it pulls power from a continuous DC source between 220 and 440 volts, delivering 250 to 3,000 amperes over weld times of 100 to 1,500 milliseconds. The gun lifts the stud to strike an arc, melts both the stud base and the parent metal, then a spring plunges it home with enough force to drive into the molten pool.

This plunge creates genuine penetration, allowing drawn arc to weld fasteners up to 1-1/4 inch in diameter to heavier base material. For studs above 12 mm (roughly 1/2 inch), a single-use ceramic ferrule is recommended. Below that, the smaller pool is often able to hold itself.

Short Cycle Drawn Arc: A Middle Ground

Short cycle drawn arc takes the strength of a drawn arc weld and trims down the heat input. Most machines limit it to about 100 milliseconds total, with arc times often only 20 to 30 milliseconds. It’s typically used for studs 16 mm or smaller, and can weld base material as thin as roughly 0.5 to 1 mm with far less distortion than full drawn arc.

However, this speed comes at a cost. The shallower molten pool means less penetration than its full-cycle counterpart. For applications that require full penetration, such as shear connectors, short cycle simply isn’t the right choice. For studs above roughly 8 mm, argon or an argon-CO2 mix is often used in place of a ferrule for shielding.

Comparing the Options

Process	Stud diameter range	Weld time	Minimum base thickness	Ferrule / gas
Drawn arc	Up to 1-1/4 in.	100 to 1,500 ms	Heavier structural base material	Ceramic ferrule recommended above 12 mm
Short cycle drawn arc	Typically 16 mm or smaller	Up to ~100 ms (20 to 30 ms arc time)	Approx. 0.5 to 1 mm	Argon or argon-CO2 often used above ~8 mm
CD tip ignition	Roughly M3 to M10	1 to 6 ms	Thin and sheet metal grade	None required
CD gap or lift ignition	Roughly 2 to 10 mm	1 to 6 ms	Thin and sheet metal grade	None required

The Physics Behind the Limits

These ranges aren’t arbitrary. The weld base area scales with the square of the stud diameter, so current and time rise roughly by the square as well. Doubling a stud’s diameter can require about quadruple the energy to form a proper weld.

This also separates CD and drawn arc from an operational standpoint. Drawn arc allows the operator to adjust both current and weld time independently. CD has no adjustable weld time, as the discharge is fixed to the capacitor dump. Instead, larger capacitor banks and higher charge voltages are what extend its maximum weldable diameter. To dive deeper into the fundamentals of these setups, stud welding equipment and accessories is a helpful reference.

The Stud Catalog: CD, Arc, Shoulder, Bi-Metallic and Refractory Studs

A stud looks like a piece of threaded rod until you order one. Then every catalog reveals four decisions behind the part numbers: which process attaches it, what shape the back of it needs, what it carries, and what it welds to. Learn those four and the catalog stops being a wall of noise and starts being a map.

The Hanlon product catalog groups studs by process family first and end configuration second, which is roughly how you should think about them too.

The capacitor discharge families

Capacitor discharge (CD) studs are the workhorses of sheet metal fastening, and the naming is more logical than it looks. The letters describe base geometry and whether the stud carries a thread.

• CDF (flanged): a flange at the weld end gives a larger footprint at the base of the weld, useful when you want more bearing surface or the stud carries a load in shear.
• CDNF (non-flanged): the plain version, chosen when the footprint must be as small as possible or a flange cannot sit flat.
• CDFNT and CDNFNT (no-thread): flanged and non-flanged studs with no thread. They weld in place as a locating point, anchor, or attachment for a later-installed component rather than for a nut.
• CDDA (drawn or stored arc): CD studs used with a drawn arc or stored arc gun configuration, bridging the two processes when a job needs CD convenience on a slightly larger diameter.
• TAP (tapped): supplied with 8-32 or 6-32 threads and a maximum tap depth of 5/16 inch. The hole is pre-tapped, so you weld it and the nut goes straight on. No tapping, no chasing threads after the arc is out.

CD studs are often the answer on finished sheet because the process leaves no reverse-side marking, and thin aluminum or stainless surfaces are unforgiving of cosmetic damage. If aluminum is in the picture, how you prep the aluminum still matters even though a CD weld is not a conventional arc weld.

Special-purpose CD products

• Bi-metallic (BM) studs: a 10 or 12 gauge stainless steel pin joined to a 5000-series aluminum base. The aluminum base absorbs the discharge while the stainless pin carries the load or provides the electrical path, so you get two material properties in one fastener.
• Annular ring stud: a stainless pin on an aluminum base, used with a keyhole slotted washer plus an annular ring or a mushroom cap. It locks a fastener in place so it cannot spin or back off.
• Notched end stud: end geometry deliberately interrupted so it cannot rotate or pull free after welding.
• Acoustic hanger stud (CDFAH): built for hanging ductwork and ceiling systems, equal in capacity to a #10 fastener, with published dimensions of 1-1/8 inch length and 1/16 inch thickness.
• Nylon wire tie-down stud: a stainless steel stud with nylon 6/6 properties and a slot height of about 0.090 inch. It holds wire bundles up to 1 inch in diameter, so you can skip drilling holes in ductwork or panels.

Drawn arc and shoulder families

Arc studs are larger and built for structural work. ARCFT full-thread studs run from 3/16 inch through 1 inch in diameter. SB shoulder studs run from 1/4 inch through 3/4 inch, with a weld base diameter larger than the thread diameter. The bigger base gives the arc more material to melt and more penetration into the parent metal, while the smaller thread stays at a standard size for the nut you will use. If you need structural penetration on aluminum rather than sheet metal attachment, stud welding is a different conversation from aluminum MIG welding, and the stud is usually the better answer.

Refractory anchors

Refractory anchors come in rectangular (REC), steer horn (ST), and Y-type patterns, and they live in a hotter, harsher world than ordinary studs. Type S4 anchors are solid fluxed, so the flux is part of the stud rather than a separate consumable. For mild steel they use low carbon steel with a minimum cold-drawn tensile strength of 55,000 psi and a minimum reduction in area of 50 percent. For stainless, Type 304 is the most common grade, while Type 303 is generally excluded because its free-machining sulfur content makes it poor for elevated-temperature service.

Materials and mechanical properties

Material	Chemistry / grade notes	Tensile (min)	Yield (min)	Elongation
Low carbon steel	Carbon 0.23% max, phosphorus 0.04% max, manganese 0.90% max, sulfur 0.05% max	60,000 psi	50,000 psi	20% in 2 in
5000 series aluminum	Aluminum 1100 and 5000 series available	42,000 psi	30,000 psi	Not stated
Stainless steel	AISI 302, 304 and 305	85,000 psi	40,000 psi	Not stated
Brass	Lead-free 70-30	70,000 psi	50,000 psi	Not stated

Plating follows the same logic. Copper plating is standard on brass studs, and cadmium, zinc and nickel platings are available to ASTM A165 Type TS, A164 Type RS and B-456. One detail is worth internalizing: the welding end of a plated stud is deliberately left unplated, because zinc or cadmium under the arc causes contamination, porosity and a weak weld. The bare end is a feature, not an oversight.

Studs can also be annealed to increase ductility, which lets a stud bend during testing instead of cracking. Published targets are about 75 Rockwell B for low carbon steel and 90 Rockwell B for stainless steel.

Cross-references for ferrules, accessories and OEM part numbers live at studwelderaccessories.com, and the equipment side of the business is covered at Hanlon Equipment. Once you know which family a stud belongs to and what the base material can support, the next question is machine setup, where lift and plunge either make or break the weld.

I’ll write section 5 covering machine setup — lift, plunge, weld time, current, electrical setup, and the pre-weld checklist.

Setting the Machine Up Right: Lift, Plunge, Weld Time and Current

Talk to anyone who runs stud welding for a living and ask which adjustment gets messed up most often on a rental gun, and you will usually get the same two answers: lift and plunge. Everything else on a stud welding machine can be dialed in from a chart or a controller screen. Those two settings are mechanical, they live on the gun itself, and they get knocked out of position the moment somebody drops a gun off a truck or a tech opens the gun for a clean and forget to put it back exactly as it was.

Get lift and plunge right and the weld will look the same on the tenth stud as it did on the first. Get them wrong and you will spend a shift chasing spatter, incomplete fillets and inconsistent flash even though your machine settings are perfectly correct.

Lift: The Gap That Makes the Heat

Lift is the distance the gun raises the stud off the base plate before the arc strikes. On a drawn arc gun, depressing the trigger energizes a solenoid that pulls the stud up a small distance, creating an air gap between the stud base and the workpiece.

That gap is the whole point. An air gap raises the electrical resistance of the circuit, and resistance generates the heat needed to melt both the stud base and the parent metal. Without the gap, the stud sits on the plate, the circuit shorts to the base metal, and you do not get enough energy at the joint to produce a fusion weld. Stud welding accessory suppliers describe the same principle in slightly different words: the lift sets the arc power, and the arc power sets the weld.

Typical lift requirements run from 1/16 inch to 3/32 inch. One manufacturer currently recommends 3/32 inch for all stud welding applications, which is a useful default when you have no chart in front of you. The practical point is that lift rarely needs changing. Once the gun is set, it stays set until the gun is disassembled, cleaned or repaired.

Plunge: The Portion That Makes the Fillet

Plunge is the amount of stud that protrudes beyond the ferrule when the gun is in its normal, unloaded state. That protruding length is the material available to form the weld fillet around the base of the stud, and it is also what determines how much spring pressure drives the stud into the molten pool.

Plunge is a two-way compromise, and both failure modes are common enough to recognize on sight:

• Too much plunge and the stud is slammed into the pool hard enough to throw molten metal everywhere. You get excessive spatter, and paradoxically you can still end up with an incomplete or uneven fillet because the metal was displaced rather than shaped.
• Too little plunge and there is not enough material to build a proper fillet. The joint looks underfilled, and the flash will not wrap fully around the base.

Plunge is typically set at 1/8 inch, excluding the flux ball on the base of the stud. That flux ball and the ceramic ferrule are what protect the weld pool: the flux tip cleans the molten pool as it burns, and the ceramic ferrule contains and shapes the molten metal while shielding it from the atmosphere. When you are short on plunge, you are short on fillet material, and no amount of extra current will fix it.

Vertical wall stud welding needs more plunge than a flat application. Around 3/16 inch is the usual recommendation for vertical walls, because gravity works against you and the pool wants to run rather than wrap around the base.

Drawn Arc: Time and Current Have to Match the Stud

On a drawn arc machine the operator sets three things, plus gas where the process uses it: lift height, weld time, and current. Modern controllers store those values per stud size, so once you establish a good parameter set for, say, a 1/2 inch stud, you can recall it later and reproduce the chart exactly instead of guessing.

Current and weld time are not independent dials. They have to be matched to both stud diameter and base material thickness. Because the weld base area scales with the square of stud diameter, a modest step up in stud size means a large step up in required energy. Add base material thickness into the same equation and the answer changes again, since thicker plate absorbs more heat before it melts.

Never carry a setting over from one stud size to another. A parameter set that produces a textbook weld on a 3/8 inch stud will burn through a thin deck or spatter the joint on a 5/8 inch stud. Set every new diameter from the manufacturer chart, weld a coupon, and bend test it before you weld production.

Capacitor Discharge: One Setting and a Fixed Cycle

On a CD machine the routine adjustment is much simpler. The operator selects the charge voltage for the stud diameter, the capacitor bank charges, and the discharge itself determines the weld time. There is no separate time dial, because the weld time is a byproduct of the discharge through the ignition tip.

That makes CD less forgiving in one way and more forgiving in another. It is less forgiving because you cannot trim heat input the way you can with a drawn arc machine. It is more forgiving because a correctly set CD machine repeats the same weld cycle stud after stud, and Hanlon’s CD stud catalog keeps the size to voltage mapping straightforward.

Electrical Setup: Where Most Erratic Welds Come From

Use the correct gauge weld cable. Keep lead length as short as practical, because every extra foot of cable is resistance and inductance working against you. And use a dedicated ground clamp attached directly to the workpiece, not through a joint or through a length of decking.

A poor ground is one of the most common causes of erratic welds. It shows up as a stud that welds fine in one spot and not another, or as a flash that circles only part of the base. Clamp to the part you are welding, close to the weld, and add a second ground lead on larger or less conductive workpieces.

The Pre-Weld Checklist

The AWS D1.1 stud welding qualification form gives you the exact set of parameters worth recording before the first weld of the day. Mirror it:

• Machine make and model
• Stud gun make and model
• Weld time in seconds
• Current in amperage
• Polarity: DCEN (straight) for structural arc stud welding
• Lift
• Plunge
• Weld cable size and length
• Number of workpiece ground leads

Photograph those settings with your phone and record them in the log at the start of every shift. It takes two minutes, and it settles arguments on a job that has been running for three weeks, when nobody remembers which ferrule was used or whether the machine was on the 5/8 inch program or the 3/8 inch one.

Codes, Qualification and Certification: What AWS and ISO Actually Require

If an inspector shut down a stud welding job, it probably was not the welds. It was the paperwork. AWS treats stud welding as its own process, with its own clause, qualification forms and production test ritual, and D1.1 does not lump it in with shielded metal arc, flux shielded arc or gas shielded arc welding. It is handled separately for procedure qualification, personnel qualification and inspection, and each of the three can stop a job on its own.

The current edition is AWS D1.1/D1.1M:2025, approved by ANSI on March 19, 2025. It is the 25th edition of the Structural Welding Code-Steel, available through the American Welding Society, and stud welding gets its own clause. The 2025 summary of changes added provisions for Type D studs, the category covering the larger shear connector formats used in composite construction.

D1.1 is not automatically law. It is a consensus standard, enforceable only when a contract, project specification, building code adoption or owner’s quality plan references it. That reference is close to universal in structural steel work, so on commercial structural jobs “do I have to follow D1.1?” is almost always yes, while industrial or non-spec work is more discretionary. If the spec is silent, ask the engineer of record.

Prequalification: The Fast Track Most People Miss

The code is more generous here than most welders expect. Studs applied in the flat (down-hand) position to a planar and horizontal surface are prequalified by virtue of the manufacturer’s stud base qualification. If the stud maker already qualified that geometry and you are welding it flat onto flat horizontal steel, you skip your own qualification test. Flat position means a slope of 0 to 15 degrees; beyond that, you are on your own.

Contractor qualification testing is required when:

• Studs applied to non-planar surfaces, such as curved or sloped beyond 15 degrees.
• Studs applied to a planar surface in vertical or overhead positions.
• Studs welded through metal decking, which changes the heat path and the ability to inspect the root.
• Studs welded to steels outside Groups I and II in the code’s base metal table, including higher-strength grades.

For structural shear connectors, the U.S. Army Corps of Engineers UFC 3-320-01 describes requiring ten specimens that pass a 90 degree bend test with representative material and application, or alternatively a tension test method per D1.1. Ten specimens is a small program, but it still needs a qualified procedure and a place to pull coupons.

Pre-Production Testing: The Two Studs at the Start of the Shift

Qualification proves you can weld. Pre-production testing proves you still can, at 7 a.m. on the third day, on a different deck panel. The AWS D1.1 procedure is simple: at the start of each day or shift, the operator welds two studs and checks them.

• The weld must show a full 360 degree flash of uniform shape around the base.
• The stud must be bent at least 30 degrees with no crack or fracture of the stud or of the heat-affected zone.

A failure is not a paperwork problem. You stop production and troubleshoot. Common culprits are a dirty base metal, a degraded gun spring, a loose ground connection, or parameters borrowed from a different stud diameter.

Stud Material: What the Code Expects From the Fastener

Codes put a floor under the fastener too, since an understrength stud fails no matter how good the weld is.

Stud Type	Minimum Tensile	Minimum Yield	Elongation
Type B (shear connectors)	65,000 psi (450 MPa)	51,000 psi (350 MPa)	20%
Type A (general purpose)	60,000 psi (415 MPa)	50,000 psi (345 MPa)	20%

Type A studs are general purpose fasteners. Type B shear connectors carry the higher requirement because they transfer shear through composite beams, so the fastener has to hold up to both the weld and the thread.

The Supporting Documents: C5.4, ISO 13918 and ISO 14555

D1.1 tells you when you are qualified. The other standards tell you how the process works.

ANSI/AWS C5.4, the Recommended Practices for Stud Welding, is the most useful document for a working operator. It covers process variations, stud design, equipment, procedures, quality control and safety for both arc and capacitor discharge stud welding. The C5.4 errata and preview shows its structure.

ISO 13918:2017 specifies studs and ceramic ferrules for arc stud welding, including dimensions, materials and mechanical properties. It is what your supplier and inspector reference when debating whether a ferrule suits a given stud diameter and material.

ISO 14555:2025 is in its fifth edition, published in July 2025, covering arc stud welding of metallic materials: procedure specifications, qualification of procedures, operator qualification, production testing and examination methods. The 2025 edition adds a simplified production test and a ring test provision, giving shops more field flexibility. Details are at iso.org, and the companion stud and ferrule specification is ISO 13918.

For shops working in aluminum or stainless rather than carbon steel, base metal preparation drives everything downstream. This guide to prepping aluminum for welding is worth reading before a CD job on sheet aluminum, because capacitor discharge leaves the reverse side unmarked, with no visual cue that the surface was cleaned.

How to Keep the Paperwork Straight

Most code disputes are administrative rather than technical, and a simple habit set prevents nearly all of them:

1. Keep the current code edition on site and know which edition the spec names. A 2021 contract may still reference the 2020 edition of D1.1.
2. Record machine and gun make and model, weld time, current, polarity, lift, plunge, cable size and length, and the number of ground leads.
3. Log every pre-production test: date, shift, operator, stud type, base material and thickness, and the result.
4. Confirm stud certification. Type B shear connectors should arrive with material certification matching the 65,000 psi and 51,000 psi requirements.
5. Keep a record of gun repairs and adjustments, since a changed spring or rebuilt gun can invalidate earlier settings.

The bottom line on codes is reassuring. Weld clean, match parameters to the stud diameter, ground properly, bend-test two studs every shift, and you are doing exactly what the codes ask. The paperwork proves you did those things; it does not complicate them. This stud and accessory catalog shows how the parts and consumable supply chain fits together, and which sizes and materials you will be certifying against.

Inspection and Quality Control in the Field

Stud welding puts an arc on the workpiece for a fraction of a second and then hides the result under a steel pin. You cannot see the joint, so you judge it by what shows around the base and confirm it by loading it until something breaks. A supervisor who knows what a good stud weld looks like can catch a bad gun setting before the crew welds two hundred more.

What a Good Stud Weld Looks Like

A sound drawn arc weld shows a full 360 degree flash of expelled metal around the base of the stud, continuous and reasonably uniform in shape and size. No undercut into the stud, no gaps in the ring, and no sign of incomplete fusion where molten metal failed to wet the parent metal.

See a clean crescent of flash on two sides and bare base metal on the other two and you know the arc was not circling the stud evenly. That usually means the gun was not seated square, the ground was weak, or the base metal was too dirty to conduct the heat properly.

The Four Production Checks

The AWS D1.1 stud welding qualification form carries a standard set of acceptance options, and they map onto four checks:

• Visual examination. Look for flash continuity, fillet shape around the base, and any sign of undercut or cracking. The fastest check, and the one that catches most problems.
• Bend testing. The stud is bent 30 degrees and must not fracture at the weld or in the heat-affected zone. AWS D1.1 pre-production testing requires two studs welded at the start of each day or shift, each bent at least 30 degrees, with no cracking in the weld zone or heat-affected zone. If either one fails, troubleshoot before production continues.
• Tensile testing. The stud is pulled off the base metal to failure and the ultimate strength is recorded. The destructive test used for qualification, and the only way to measure actual strength rather than infer it.
• Torque testing. For threaded studs, this checks thread-holding performance under twist. On the AWS qualification form, torque testing is optional for threaded fasteners only.

The ISO 14555 Framework

ISO 14555, the fifth edition published in July 2025, gives arc stud welding its own production testing framework. It separates the production test from the simplified production test, giving fabricators a defined path depending on the application and its risk level. The standard also lists macro examination, radiographic examination and the ring test as supplementary methods.

Macro examination is worth understanding even if you never cut one yourself. The technician sections a test weld and examines it under magnification, checking the fusion zone and the depth of penetration into the base metal. It tells you something visual inspection cannot: whether the weld melted into the base plate deeply enough to carry structural load. The ring test works from the other direction, checking a stud that has been sectioned to reveal the same information without a destructive pull.

For structural shear connector work, the U.S. Army Corps of Engineers guidance in UFC 3-320-01 points toward ten specimens that pass a 90 degree bend test with representative material and application, or an alternative tension test method. AWS C5.4, Recommended Practices for Stud Welding, covers the quality control requirements for both arc and capacitor discharge work in detail.

The Shift QC Workflow

A competent contractor runs the same routine every shift, and it takes less time than the welds it protects:

1. Confirm settings match the WPS. Gun and machine settings are checked against the procedure specification before the first stud. Current and time carry over from one stud size to another only by accident, and that is how a whole run of undersized fillets gets made.
2. Verify studs and ferrules. Correct diameter, correct material for the base metal, correct ferrule size for that stud.
3. Check the base metal surface. Mill scale, paint, primer, oil and moisture all cause poor welds, and they all cause cracking later.
4. Run the pre-production test. Two studs, both bent 30 degrees, both clean.
5. Inspect a sample of production welds visually. Not every stud, but a defined sample, with the flash checked on all sides.
6. Bend test on a defined frequency. Write the frequency into the inspection plan rather than leaving it to memory.
7. Record everything. Settings, lot numbers, test results, and any corrective action taken.

When a Test Fails

Any failed bend, tension, or torque test triggers the same sequence: stop production, quarantine the welds made since the last passing test, find the cause, correct it, and re-qualify before resuming. The cause is usually one of three things: dirty work, wrong settings, or a tired gun. Chasing those three first resolves most failures without pulling apart equipment.

At shift end, the inspector expects the pre-production test results, the visual inspection log, the bend test log with dates and initials, and a record of any parameter changes made during the shift along with the tests that justified them. Sheets like the one described in the AWS D1.1/D1.1M:2025 stud welding forms exist for exactly this purpose, and keeping them current is often the difference between a clean sign-off and a three-day argument about who welded what.

If your work involves aluminum or stainless fasteners rather than plain carbon steel studs, the same visual and mechanical logic applies, but prep discipline matters even more. Guides on cleaning aluminum for welding and on practical aluminum MIG welding cover the surface preparation side of that problem in more detail.

Troubleshooting the Stud Welds That Go Wrong

Studs that look fine from ten feet away and fail the moment somebody hits them with a pry bar will derail a shift fast. Stud welding is repeatable with few variables, so nearly every failure lands in one of three buckets: dirty work, wrong settings, or a tired gun. Diagnose by symptom, not guesswork.

No Flash or No Bond

No ring of expelled metal around the stud base means the arc never formed or the pool never fused to the plate. Paint, primer, oil, mill scale, and heavy galvanizing all insulate the joint, so check contamination first. Then check current: too little for the stud diameter leaves the base barely melted, and a stud beyond machine capacity behaves the same way. Finally, confirm the gun was seated firmly against the work and the workpiece was grounded.

The fix is unglamorous: grind back to bright metal with an angle grinder, attach a dedicated ground clamp directly to the workpiece, check settings against the published chart or WPS, and confirm the stud and ferrule match the base metal. On aluminum, surface prep deserves extra care, and how to prep aluminum for welding covers the oxide removal that keeps arc-type fasteners from bonding reliably.

Spatter and Burn-Through

Spatter flying off the pool or a hole punched through thin deck is nearly always a heat-input problem: too much current or too much weld time for the base thickness, or too little plunge to control the pool. Weld time must be matched to stud diameter, so a timing set up for a 7/8 inch stud burns clean through 10 gauge sheet.

Drop current or time to the chart value for that diameter and thickness, raise plunge to roughly 1/8 inch so the ferrule shapes the fillet, then re-test before returning to production. The aluminum MIG welding guide shows how low-heat settings behave on thin sections, and a capacitor discharge process may suit the job better.

Incomplete or Partial Fillet

A partial sweep of fillet around the stud, or a flat collar instead of a cone of flash, points to mechanics rather than chemistry. Too little plunge leaves the ferrule off the work, excessive lift starves the joint of heat, a worn gun spring drives the stud in unevenly, and a worn or mismatched ferrule cannot contain the pool. Reset plunge and lift, service the spring, and fit a new ferrule. Ferrules are single use and must match the stud diameter and weld parameters, and AWS C5.4 recommended practices for stud welding lists ferrule defects as its own troubleshooting category for arc and CD work.

Cracks in the Weld or Heat-Affected Zone

Cracking usually means contamination or moisture got into the molten pool, or the stud was welded into heavy rust where scale acts as a stress concentrator. Clean back to bright metal with a grinder, dry it thoroughly, and let it cool naturally before handling. Since the joint was made under unqualified conditions, re-run the pre-production test and treat those studs as suspect until they pass a bend test.

Arc Blowout or Erratic Arc

An arc that wanders, spits sideways, or refuses to hold is an electrical problem, not a welding problem. Culprits are a poor ground, a workpiece too small to carry the current, long or undersized ground leads, and a workpiece that is not electrically continuous, such as a deck panel floating over a non-conductive spacer. Clamp directly to the workpiece near the weld, add a second workpiece lead on long jobs, and upsize the cable if the leads run long, which is standard practice for stable arc stud welding.

Stud Not Sinking, Stubbing, or Lifting Off

A stud that sits proud of the surface after the cycle finishes has not been plunged. Check the gun spring, which weakens with age and use, and the plunge setting, often too short on rental guns. Weld time set too long for the stud diameter is the other culprit, since the pool cools before the stud arrives. A stud that sticks to the base plate or lifts off on removal points to contamination, or to a lift mechanism that failed to separate the stud. Check the lift solenoid and plunger, clean the surface, and re-test. Service a gun that has been long in service rather than compensating with settings.

Slow or Inconsistent Weld Cycle on CD Equipment

Capacitor discharge machines fail in a few ways. If the cycle is slow, the capacitor bank may not be fully charged, or a capacitor has begun to fail. If the cycle runs normally but the weld is inconsistent, suspect the ignition tip on the end of the stud: a dirty or worn tip produces erratic ignition and a poor bond. Charge fully, fit a new-tip stud rather than reusing one, and service the machine if performance does not return. Consumable suppliers stock replacement tips, ferrules, and charge accessories.

Symptom	Likely cause	Fix
No flash	Contamination, low current, no arc	Grind bright, ground to workpiece, verify settings
Spatter, burn-through	Too much current or weld time	Cut current or time, raise plunge, re-test
Partial fillet	Plunge, lift, worn spring or ferrule	Reset plunge and lift, new ferrule
Crack in weld or HAZ	Contamination, moisture, rust	Clean bright, dry, bend test
Arc blowout	Poor ground, long or small leads	Clamp near weld, add lead, upsize cable
Stud will not sink	Weak spring, short plunge, long weld time	Service gun, fix plunge, shorter weld time
Stud sticks or lifts off	Contamination, failed lift	Check lift, clean base metal
Slow or erratic CD cycle	Uncharged bank, bad capacitor, dirty tip	Charge, new-tip stud, service

Strip away the specific diagnosis and nearly every stud weld failure comes down to dirty work, wrong settings, or a tired gun. Clean to bright metal every time, keep the ground clamp on the workpiece, match current and weld time to stud diameter and thickness, and change one variable at a time before re-running the bend test.

Safety: Fume, Hexavalent Chromium and Working Around Hot Work

Stud welding looks like clean work: a stud, a shot of current, a flash of orange, and the fastener is part of the steel. But that flash puts an electric arc on the workpiece, often galvanized deck, stainless or structural steel, in a mechanical room with no window to open. The plume off that arc is a real exposure, not a formality.

Here is what is in it. Welding fume contains metals including aluminum, antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, silver, tin, titanium, vanadium and zinc. It also carries gases such as argon, helium, nitrogen, carbon dioxide, nitric oxide, nitrogen dioxide, carbon monoxide, ozone, phosgene and hydrogen fluoride. OSHA’s welding safety fact sheet is a handy one-page job site reference.

Short exposure is unpleasant: eye, nose and throat irritation, dizziness, nausea, and that metallic taste that sends welders to the cooler. Breathing welding fume over time can cause lung damage and cancers of the lung, larynx and urinary tract. Metal fume fever, stomach ulcers, kidney damage and nervous system damage are documented outcomes, and manganese exposure is linked to Parkinson-like symptoms. A cough that lingers days after a shift means you breathed too much.

The Chromium Problem

Stainless steel and chrome plating contain chromium that converts to hexavalent chromium, Cr(VI), when welded. Cr(VI) fume is highly toxic: it burns the eyes, skin, nose, throat and lungs, and it causes cancer. NIOSH treats all hexavalent chromium compounds as occupational carcinogens, which is why the limits below are enforceable, not advisory. They come from OSHA’s dedicated standard: 29 CFR 1910.1026 for general industry and 29 CFR 1926.1126 for construction.

• Permissible exposure limit: 5 micrograms per cubic meter as an 8-hour time-weighted average.
• Action level: 2.5 micrograms per cubic meter as an 8-hour TWA.
• Monitoring: if initial monitoring shows exposure at or above the action level, periodic monitoring is required at least every six months.

Controls in the Order OSHA Wants Them

Respiratory protection is the last line, not the first. The hierarchy is engineering controls, then work practice controls, then PPE:

1. Clean the surface first. Remove paint, primer and solvent residue. Grinding back to clean metal kills the hazard at the source.
2. Get out of the plume. Stay upwind outdoors. Wind direction matters more than people expect on a deck pour.
3. Use general ventilation. Open the doors, run the fans, move fresh air through the space.
4. Use local exhaust ventilation. Fume extractors with the nozzle close to the source, not across the room. Distance kills capture efficiency fast.
5. Consider a lower-fume process. Substituting a process or consumable that generates less fume is a legitimate control, often the cheapest one. Capacitor discharge work on light gauge puts far less heat into the workpiece than a drawn arc weld.
6. Never weld in a confined space without ventilation. Confined spaces fall under 29 CFR 1910.146, and the atmosphere must be tested before you strike an arc.
7. Use respirators when ventilation cannot bring exposure below the limits, then follow the program under 29 CFR 1910.134: medical evaluation, fit testing and cartridge change schedules.

Hazard communication sits over all of it. Under 29 CFR 1910.1200, workers must be told what the hazards are, trained, and given labels and data. Welding, cutting and brazing is covered by 29 CFR 1910.252.

PPE and Fire Prevention

29 CFR 1910.252(b)(2)(i)(A) requires a welding helmet with the correct shade of lens for the process and amperage. Stud welding puts a very bright, short arc on the workpiece, and the flash is still a UV and infrared burn risk, so the helmet is not optional even on a two-second cycle.

• Long leather gloves, full clothing, no polyester. Melted synthetic fabric bonds to skin and has to be cut off.
• Keep the welding area at least 35 feet from flammable and combustible materials. On a deck job that means moving fuel tanks, cylinders and cardboard.
• Keep a fire extinguisher within reach.
• Keep a fire watch on the area for at least 30 minutes after welding finishes. Deck fires start behind the rib, under the deck, where nobody looks.

Stud welding on light gauge and aluminum has its own hazards for the pre-job plan. Aluminum brings different fume and different fire behavior. If aluminum studs are in scope, read our practical aluminum MIG welding guide first, and how to prep aluminum right covers the solvent and oxide removal that keeps fume down and the arc stable.

The takeaway is unglamorous. Clean the metal, control the plume at the source, keep the fire watch honest, and know what the fume is made of before you light the gun. A short arc still leaves a long cloud.

Choosing, Renting or Buying Your Stud Welding Setup — and the Bottom Line

Stud welding gear gets bought in a hurry, for reasons unrelated to the job in front of you. A 3,000 amp supply is a lot of machine to own if your largest stud is a quarter inch and your thinnest base material is 16 gauge sheet. Before you talk to a supplier, answer three questions and get the answers on paper before anyone shows you a price.

• Largest and smallest stud you will ever weld? This sets your process family and machine class. Small studs on thin material point to capacitor discharge; big structural studs point to drawn arc. Hanlon lists more than 1,000 CD stud sizes and more than 600 drawn arc sizes in its stud catalog.
• Thinnest base material or deck you must attach to? Half-millimeter sheet and a 1/2 inch composite deck are different worlds: one is a capacitor discharge job, the other an arc job through metal deck.
• How many studs per day and per project? Volume decides whether you own equipment, borrow it or fix what you already have.

Rent it when the work is short, uncertain or one-off

Renting is right for a trial project, a single specialty job, a deck retrofit with a date attached, or any time you are not sure which studs you will weld. Hanlon’s rental fleet runs from small CD systems up to full ARC systems, with weekly and monthly terms, plus a diesel generator stud welding rig for Chicago-area jobs without adequate site power. A machine needing 440 volts will not run off a temporary panel, and waiting on an electrician is an unpriced schedule hit.

Repair it when the machine still has life in it

Most stud welding problems are a tired gun spring, a worn contactor, a bad capacitor pack or a corroded connector, not a dead machine. Repairing is almost always cheaper than replacing. Hanlon services most makes of stud welding equipment, including Truweld, Midwest Fasteners, AGM, Proweld International, H.A. Jones and Erico, with a typical turnaround of one to two days and rentals to cover the downtime.

Send the power supply, the gun, the extension cables and the ground cables back together: faults that look like a machine problem are often a cable or clamp problem.

Buy it when volume is steady and somebody runs it

Ownership pays off when the same machine is in use every week and a named operator understands lift, plunge, current and time. A machine nobody owns internally gets its settings changed by six different people and produces inconsistent welds. Before you buy, work through this checklist.

• Range coverage: does it cover your full stud diameter range, or only part of it?
• Parameter storage: can the controller store per-stud parameter sets? That lets a crew reproduce a qualified parameter chart shift after shift.
• Serviceability and support: are the gun, lift mechanism and trigger serviceable, are parts easy to get, and will the supplier train a new operator and take a call from a job site?
• Capacitor bank size: is it sized for your largest CD stud, with headroom?
• Calibration and maintenance path: documented program, or are you relying on hope?
• Consumables and accessories: what does the supplier stock, and how fast do they ship? Running out of ferrules on a Thursday stops a project. Our buyer’s guide to welding supplies and gases covers consumables and shielding gas ordered separately from the machine.

The real cost of ownership

The sticker price on a power supply is a minority of the machine’s real cost over its life. Build the number out loud:

• Studs and ferrules, consumed per weld. Ferrules are single use and must match stud diameter and weld parameters.
• Weld cable and clamp replacement, because cables are chewed, burned and clamped into ruin like consumables.
• Capacitor service life on CD machines, a scheduled cost rather than a surprise.
• Routine maintenance and calibration, plus bench time for the gun.
• The cost of a failed weld, the biggest line: ground-down base metal, a rejected connection, an inspector’s stop-work, an unpriced delay.

How to evaluate a supplier

Judge the supplier the same way whichever route you take: stock depth across the sizes and materials you use, the ability to cross-reference OEM part numbers, technical support that understands both capacitor discharge and drawn arc well enough to tell you which one you do not need, repair turnaround you can plan around, and advice about the job in front of you rather than an upsell to the largest machine on the shelf. A supplier like Hanlon Stud Welding, family-owned in Elk Grove Village, Illinois since 1960, shows what good looks like: deep catalog, rentals and in-house repair under one roof.

The bottom line

Hanlon Stud Welding is a long-running Chicago-area supplier of studs, accessories, rentals and repairs covering capacitor discharge and drawn arc work. Your process choice follows from stud size, base material thickness and required penetration; weld quality follows from setup discipline on lift, plunge, current and time, plus clean work and a sound ground. AWS D1.1/D1.1M, AWS C5.4, ISO 13918 and ISO 14555 set qualification and inspection expectations, and fume, hexavalent chromium and fire controls are not optional.

Next steps, by where you are

• You already own a machine: record settings for your top five stud sizes, run a pre-production bend test, and rule out contamination, settings and a worn gun first.
• You are renting for the first time: ask for a parameter chart for your stud diameter and base thickness, and request a demo weld on your own material.
• You are buying: take the checklist to the supplier and insist on a demo on your base metal, not a showroom sample.
• You have a project in front of you: get code requirements in writing before the first stud, and confirm the inspection and test frequency.

Frequently Asked Questions

What is Hanlon Stud Welding?

Hanlon Stud Welding is a family-owned supplier of stud welding equipment, weld studs and insulation fastening products based in Elk Grove Village, Illinois, in business since 1960. It is not a manufacturer of welding guns; it sells, rents and repairs equipment from brands such as Nelson, Truweld, Proweld, Midwest Fasteners and Image Industries, and stocks more than 1,000 CD stud sizes and more than 600 drawn arc sizes.

Should I rent or buy a stud welder?

Rent for short-duration or unpredictable work, trial projects and one-off specialty jobs, since weekly and monthly rental terms avoid tying up capital. Buy once you have steady weekly volume and a dedicated operator. If you already own a machine, repair is often the cheapest option, with typical shop turnaround of one to two days and rentals available to cover the downtime.

How do I know whether I need capacitor discharge or drawn arc?

Capacitor discharge is the right choice for thin sheet and small studs up to about 3/8 inch, where you need minimal heat input, no back-side marking, 110 volt power and high cycle rates. Drawn arc is required for larger structural fasteners, deeper penetration into heavier base material, and composite construction shear connectors, and it needs DC power at 220 or 440 volts.

How long does a single stud weld take?

AWS cites about 0.13 seconds for a 10 gage (0.134 inch) stud and about 0.92 seconds for a 7/8 inch stud in drawn arc work. Average application rates run around six studs per minute, with fifteen per minute common in many applications, and capacitor discharge machines can reach up to 20 welds per minute.

Do I have to be AWS certified to weld studs?

AWS D1.1 does not issue a welder certificate for stud welding; instead it requires a pre-production test at the start of each day or shift to qualify the operator, equipment and setup for that shift. Longer-term procedure and application qualification testing is required for studs welded through decking, on curved or vertical surfaces, or to steels outside the code’s listed groups.

What does the 30 degree bend test prove?

The bend test is the field proof that the stud fused properly to the base metal. Two studs are welded at the start of the shift and bent at least 30 degrees; if the stud fractures, or a crack appears in the weld zone or heat-affected zone, the setup must be corrected before production welding continues.

Can you stud weld aluminum or stainless steel?

Yes. Aluminum, stainless and brass studs are available in the standard sizes, and each material has its own published tensile and yield values, so settings and filler must match the base metal. Stainless work means welding fume containing hexavalent chromium, which OSHA regulates with a permissible exposure limit of 5 micrograms per cubic meter as an 8-hour time-weighted average.

Why am I getting spatter and burn-through on thin material?

The most likely causes are too much current or weld time for the base metal thickness and too little plunge, which is typically set at 1/8 inch excluding the flux ball. Reduce current or time to the published chart for the stud diameter, increase plunge slightly, confirm lift is around 1/16 to 3/32 inch, and re-run the pre-production bend test.

What is the correct ferrule for my stud?

Ferrules are matched to stud diameter and are single-use consumables that concentrate heat, shield the molten pool and shape the visible fillet. A ceramic ferrule is generally recommended above 12 mm stud diameter in drawn arc work, and using a worn, cracked or mismatched ferrule is a common cause of incomplete fillets, spatter and erratic arcs.

Is stud welding safe to do on galvanized steel deck?

It can be done safely, but zinc-coated surfaces generate zinc fume, so the surface must be cleaned of contaminants and the area ventilated. OSHA requires welding surfaces to be free of solvent residue and paint, local exhaust ventilation with the nozzle close to the plume, and respirators where ventilation cannot keep exposure below the limits.