Four machines for structural steel marking
Permanent marking on metal comes down to depth, and depth comes down to what happens to the part next. Pick by where the piece is and where it goes after.
Structural Steel · Beams · Plates · Stampings · Castings
Marking Machines for Steel Fabrication
A piece mark has to be readable when the steel reaches the site — after cutting, welding, blasting and galvanizing. HeatSign builds machines that put the mark deep enough to get there.
Cordless Dot Peen · Battery
For beams you cannot move
$1,950 – $2,850
No cable and no air line. You carry it to the beam instead of moving the beam to a machine. An electromagnetic base holds it on the steel while it marks, which is what field structural steel marking actually needs.
Battery powered | bracket rubber base holds on steel
Works in the yard, on the rack, or up on staging
Works in the yard, on the rack, or up on staging
Beams . Columns . Girders . Trusses . On-site work
HS-PE01-P · Pneumatic portable
The deepest mark, for parts that get galvanized
$1800 ~ $2500
Compressed air pushes the pin harder than an electric motor. The machine sets the force, and how deep that force goes depends on how hard your steel is — softer structural grades take a deeper mark than hardened or high-strength steel.
Marking depth up to 1 mm on soft structural grades, less on hard steel | marking area 140 × 60 mm
Built-in touchscreen, no PC needed | Needs compressed air
Built-in touchscreen, no PC needed | Needs compressed air
Pre-galvanizing . Castings . Thick plate . Forgings
Bench Dot Peen · Electric
Bench work and marking on stamped sheet metal
$1900 ~ $2900
A fixed table and the same position every cycle. This is what most shops buy first for cleats, gussets, base plates and stamped brackets — the parts small enough to carry to a station.
Electric drive | No air line needed
Text, piece marks, heat numbers and Data Matrix from one file
Text, piece marks, heat numbers and Data Matrix from one file
Cleats . Gussets . Base plates. Stampings . Fittings
MOPA Fiber Laser
The only safe way to mark after galvanizing
$3500 – $6000
Once the zinc is on, a deep mechanical mark would break it. MOPA runs at a low, controlled power that marks the zinc surface without cutting through to the steel underneath — which is what stops rust starting at the mark.
Adjustable pulse, low power | Marks without breaking the zinc
Also used for fine Data Matrix on machined faces
Also used for fine Data Matrix on machined faces
Post-galvanizing . Machined faces . Nameplates . Data Matrix
About the depth figures. A dot peen machine sets impact force, not depth. How deep that force goes depends on how hard the steel is — the same setting marks A36 deeper than it marks a hardened or high-strength grade.
Tell us the grade and we will tell you what to expect, from having marked most structural grades many times over.
Galvanized steel marking: before or after the kettle
Steel structure marking has one question that changes everything: which side of the galvanizing kettle you mark on. Most suppliers only answer half of it.
Same plate, same kettle, two marks. The shallow mark filled in. The deep one did not.
Tell us which side of the kettle you mark on. It is the first question we ask, because the answer rules out half the machines before anything else is discussed.
Marking before galvanizing
Go deep. The zinc will cover it.
Zinc fills the mark but keeps its shape, so a deep mark is still readable through the coating.
marking depth up to 1mm (per material) Dot peen on soft structural steel — far deeper than the coating. Less on hard grades
- Use pneumatic dot peen for the deepest mark
- Zinc coating runs roughly 45–85 µm
- Character height matters more than depth alone
- Cheapest and most common route
Marking after galvanizing
Go shallow. Breaking the zinc starts rust.
A mechanical mark cuts through the zinc and leaves bare steel showing, and that spot starts to rust.
MOPA only Low, controlled power — not a standard fiber at high power
- Use a MOPA fiber laser, low power
- Do not use dot peen or a high-power fiber
- If the zinc is breached, the spot needs a zinc-rich repair coat
- That repair is manual labour, on every affected piece
What a steel fabrication shop marks
Piece marks and heat numbers are different jobs. Most shops need both.
Part | What goes on it | Where it is marked | Machine |
|---|---|---|---|
Beams, columns, girders | Piece mark · heat number · job number | On the rack or in the yard | |
Plate and thick sections | Heat number · grade · cutting list ID | After cutting, before fit-up | |
Stamped sheet metal partsbrackets, cleats, gussets | Part number · batch · material code | At a bench station | |
Cast steel and cast iron parts | Pattern number · heat · cast date | On the rough surface, as cast | |
Welded assemblies | Assembly mark · weld map ID · inspector stamp | After welding, before blasting | |
Galvanized finished pieces | Re-marked piece mark · shipping ID | After the kettle |
From the rack to the site
The operator carries the machine to the beam, loads the job file and marks. No cable, no air line, no lifting the beam onto a bench.
Fabrication marking: piece mark or heat number?
Metal component marking in a fabrication shop covers two different jobs, and the contract decides which one you need.
Level | What it means | Typically used on |
|---|---|---|
Lot identification | The material on a job traces back to a set of mill certificates | Most commercial work |
Piece-mark traceability | The heat number can be matched to each piece mark | Bridge main members |
Piece traceability | Every individual piece carries its own heat number | Nuclear and other critical work |
Traceability is not automatic under AISC. It applies when the contract documents call for it, and the level is chosen by the owner. Each step up costs more to run — so check the specification before you buy a machine sized for the hardest case.
Where marking goes wrong in a fabrication shop
Four things that send a piece back, or leave a crew on site guessing.
45–85 µm: Zinc coating thickness
up to 0.9 mm: Dot peen, soft steel
What we do
Ask about the coating before recommending a machine. Parts going to the kettle need pneumatic depth, not a lighter electric unit.
Deeper: Pneumatic beats electric here
Bigger: Larger characters read better
What we do
Recommend a larger character height and more impact force on castings, and tell you when a machined pad on the drawing would solve it more cheaply.
Cordless: no air line
Magnetic: Holds itself on the steel
What we do
Put a battery machine in the operator’s hand so the mark is the same on the rack as it is at the bench. Same file, same settings, same result.
Import: From a spreadsheet, not a keyboard
Auto: Serials and date codes increment
What we do
The software reads piece marks and heat numbers straight from a spreadsheet export, so the operator selects a job rather than retyping it.
How to choose a steel marking machine
Three questions. The first one rules out half the options.
Question 1
Do you mark before or after galvanizing?
Before → pneumatic dot peen, deep.
After → MOPA fiber, low power.
Question 2
Can the part come to the machine?
Yes → bench dot peen.
No → cordless, carried to the beam.
Question 3
Is the surface rough or machined?
As-cast or mill scale → dot peen.
Machined and clean → laser reads finer.
Where these machines fit. These machines are not built into a production line. An operator carries one to the piece, or brings the piece to the bench.
If your CNC line already marks every piece as it cuts, you do not need one. If your pieces come off the saw with nothing on them and someone stamps them by hand, this is what replaces the hand stamp.
Questions about structural steel marking
How big should the characters be on a piece mark?
Big enough to read from where people stand. In a yard that usually means 10 to 20 mm characters, because a crew reads the mark from a few metres away, not up close.
Larger characters also help after galvanizing, since the zinc softens the edges. Small characters that look fine on bare steel can close up once the coating is on.
Can it mark through mill scale and light rust?
Dot peen can. The pin pushes through mill scale, light rust and surface oil, so steel straight off the rack does not need cleaning first.
A laser cannot. It needs a clean, dry surface, which means an extra step before marking. On raw structural steel that step is usually not worth it.
What air supply does the pneumatic machine need?
A normal shop compressor is enough. It runs on clean, dry compressed air at standard workshop pressure, and it only draws air while it is actually marking.
What matters more than the compressor is the air quality. Water or oil in the line shortens pin life. Tell us your setup and we will confirm what you need.
How long does the battery last in a cold yard?
Cold cuts battery life, the same as with any cordless tool. In winter, expect less than the rated run time and keep a spare battery charging indoors.
Most shops mark a batch, swap the battery and carry on. If you mark all day outside in winter, ask about a mains-powered option instead.
Can we mark weathering steel and stainless?
Yes to both, with dot peen. Weathering steel marks like ordinary carbon steel. Stainless is harder, so the same setting gives a shallower mark — usually still enough to read.
On stainless that stays exposed, a mark can concentrate corrosion at that spot if the surface finish matters. Ask the engineer before marking architectural stainless.
Can we mark a piece after it has been welded?
Yes, and many shops do it that way so the mark goes on the finished assembly rather than on a part that will be cut again.
Keep clear of the weld and the heat-affected zone beside it. Mark on the parent metal, not on the weld itself, and follow whatever the fabrication drawing allows.
How much does a steel marking machine cost?
The pneumatic portable is $2,000 to $3,000. Cordless dot peen, bench dot peen and MOPA fiber are priced on how they are configured, because marking area, power and character height all change the price.
Tell us what you mark, where you mark it, and whether the pieces get galvanized. You will have a figure the same working day.