Most factories mark serial numbers on metal with a dot peen marker or a fiber laser marking machine. Dot peen punches dots into the metal that still read after paint or blasting. A fiber laser is faster and finer, for finished parts and small text.
A serial number has to outlive everything the part goes through, and someone has to read it right years later. So choose the method by what happens to the part after marking, and choose the format so nobody misreads it. At HeatSign we build both kinds of serial number marking machine for industrial serial number marking, from nameplates to frames. This page covers:
A dot peen serial number on a machined steel part.
Which method should you use to mark serial numbers?
Use dot peen if the part will be painted, blasted or coated, or if the surface is rough. Use a fiber laser for finished parts, small text and Data Matrix codes. Use hand stamps only for a few parts with short numbers. Inkjet and paint pens are not permanent.
Mark: anything the machine puts on the part: text, a serial number, a barcode or a Data Matrix code (a small square barcode, a bit like a QR code).
Dot peen marking
Fiber laser marking
Steel stamps
How it works
A hard pin punches a row of small dots into the metal
A laser beam changes the surface color or removes metal
A hammer or press drives steel letters into the metal
Under paint or after blasting
Still reads, if deeper than the coating
Light marks are lost; deep engraving survives
Reads after blasting; thick paint can hide it
Next number
The software counts up by itself
The software counts up by itself
Swap the stamps by hand
Speed
1–3 characters a second at 2 mm high (handheld)
A 10-digit serial number in a few seconds
One character per blow
Looks
Dotted, slightly rough
Smooth and sharp; black, white or engraved
Solid letters, often uneven by hand
Machine price
From about $1,300
From about $1,950
A set of stamps costs little
Dot peenSize, serial number and date along a steel pipe.Fiber laserA stainless nameplate. The serial number, bottom right, starts with the year.
Hardness matters too. Dot peen works on metal up to about 60 HRC (Rockwell C hardness); harder tool steel needs a laser.
Steel, stainless steel or aluminum: does the method change?
Metal
Dot peen
Fiber laser
Carbon steel
Marks through rust, scale and paint
Dark mark on clean steel; engrave for depth
Stainless steel
Clean dotted mark, nothing added to the surface
Smooth black mark with no metal removed; ask how it affects corrosion if the part is passivated
Aluminum
Soft metal, so the pin goes deep with little force
Light gray engraving; on anodized aluminum the laser removes the color layer and leaves a white mark
How deep should a serial number be?
Deeper than whatever will cover it or wear it away. Parts that will be blasted, painted, powder coated or galvanized need a pneumatic dot peen mark or a laser mark engraved in several passes, or a mark added after coating. Parts that stay bare need only a light laser mark.
After marking, the part is…
Mark it with
Avoid
Left bare, or only machined
A light fiber laser mark or an electric dot peen marker
Nothing special
Shot or grit blasted
Pneumatic dot peen, or laser engraving in several passes
Color-change laser marks
Painted or powder coated
Deep pneumatic dot peen, or mark after coating
Fine marks under thick paint
Hot-dip galvanized
Deep pneumatic dot peen or stamps
Laser marks and light dot peen
Heat treated
Dot peen or engraved laser marks
Laser annealing (color change only)
Marked after painting: the pin goes through the paint into the steel.
Painted parts give you a second choice: mark after painting. The pin goes through the paint into the steel, so the number shows bright against the coating.
Keep it short, fixed-length and in capitals, and leave out letters that look like digits. US vehicle identification numbers (VINs) skip I, O and Q for that reason, and a VIN inside the cab must be at least 4 mm tall. Add a date if you want the number to point to a build record.
1Use the same length every timeWrite 0001, not 1. Fixed-length numbers line up on the part, sort correctly in a spreadsheet and fit the same marking window.
2Skip I, O and QThey are easy to read as 1 and 0. The VIN letter set leaves them out (49 CFR 565.13). Do the same in your own serial numbers.
3Build in the dateThe inspection report for one of HeatSign’s MOPA laser marking machines carries a serial number made of the build date, then a 4-digit count for that day. The number alone tells you when it was built.
4Add a check digit if people type itPosition 9 of a VIN is a check digit, worked out from the other 16 characters. It exists to catch copying mistakes (49 CFR 565.15).
5Mind the length limit of the barcodeA GS1 serial number, the kind used in GS1 Data Matrix codes, holds up to 20 characters. A US military UID string holds up to 50: capitals, digits, dashes and slashes only (MIL-STD-130).
6Make it big enough to read by eyeVIN characters inside the cab must be at least 4 mm tall (49 CFR 565.13). That is a sensible floor for any serial number someone reads off a part.
A small nameplate with fixed-length numbers, marked on an electric nameplate marker.
Many of our buyers build equipment: machines, trailers and vehicle frames. The serial number goes on a data plate, on the frame, or on both. If your buyers call it “serialize” or “put the serial on”, they mean the same job.
Planning a Data Matrix or QR code too? Read Data Matrix vs QR code before you fix the format.
Which serial number marking machine fits your parts?
If the part fits on a bench, use a benchtop dot peen marker or a desktop fiber laser. If it is too big or already assembled, like a frame, beam or valve body, take a portable or handheld dot peen marker to it. For batches of nameplates, use a nameplate marker.
Yes. HeatSign’s dot peen and laser software builds each serial number from a prefix, a start number and a step, and counts up after every part. It can add the date and shift, or read the next number from an Excel or TXT list.
Method
How it works
Best for
Count up
Prefix + start number + step, e.g. HS2610-0001, HS2610-0002
Simple runs
Read a list
Takes the next line from an Excel or TXT file
Numbers set by your ERP (business software) or your customer
Live link (laser)
Gets the number from your MES (the software that tracks each part on the line)
Inline lines with full traceability
An order and serial number, height and standard on a 48 mm steel pole.
Most serial numbers are alphanumeric, letters plus digits, and both machine types handle any mix. For marking text and numbers in general, see alphanumeric marking machines.
A repeated serial number is a traceability failure. Lock the counter so no one resets it by mistake, keep a log of every number marked, and check the first part of each batch.
You can also mark a Data Matrix code that holds the same number, right next to the text, so a scanner reads it in one shot. See dot peen Data Matrix marking for which metals work.
A HeatSign handheld marker dot peen marks a serial number on an iron plate.
How much does a serial number marking machine cost?
HeatSign’s dot peen markers cost about $1,300–2,900, rotary systems for flanges and shafts $3,000–5,000, and desktop fiber laser marking machines $1,950–5,000. Pick by part size and depth first; the price follows.
Machine
HeatSign price
Fits
Nameplate marker (electric)
$1,300–1,900
Tags and data plates
Benchtop pneumatic dot peen
$1,500–2,800
Deep marks on parts at a bench
Handheld dot peen
$1,600–2,850
Pipes, brackets, installed parts
Portable pneumatic deep marker
$1,800–2,500
Frames, beams, castings
Rotary dot peen system
$3,000–5,000
Flanges, shafts and pipes
Desktop fiber laser
$1,950–5,000
Finished parts, small text, Data Matrix codes
Price ranges are HeatSign’s prices at the time of writing and depend on the configuration. Shipping is extra.
Avoid I, O and Q, which read like 1 and 0. US vehicle identification numbers leave out exactly these three. Keep every number the same length and in capitals.
Is a dot peen marker the same as a serial number stamping machine?
It does the same job with no stamps to swap. Many people who search for a serial number stamping machine want numbers punched into metal. A pneumatic dot peen marker punches them as dots, and its software changes the number for every part.
Which laser is best for serial numbers: fiber, UV or CO2?
Use a fiber laser marking machine for metal; it is also the fastest choice for serial numbers on metal parts. Use a UV laser for plastics, glass and circuit boards. A CO2 laser marks wood, paper and coatings, but not bare metal.
Is inkjet or a paint pen good enough for serial numbers?
No, not for a part that must be traced for years. Ink sits on top of the surface, so blasting, solvent or wear takes it off. Dot peen and laser marks change the metal itself.
Can I mark a serial number and a Data Matrix code together?
Yes. Dot peen and laser machines both mark the text and a Data Matrix code in one run, from the same number. Laser-marked Data Matrix codes are smaller and sharper; dot peen ones hold up better under paint and blasting.
How do you mark serial numbers on pipes and curved parts?
For a few pipes, a handheld dot peen marker marks along the pipe. For many round parts, a rotary axis turns the part while the machine marks around it. Tell us the diameter and the wall thickness.
Does HeatSign test my part first?
Yes. Send a photo, the material and what happens to the part after marking, and HeatSign replies within one business day. If you mail sample parts, we mark them and usually send photos or a video within one business day.
How fast is serial number marking?
A handheld dot peen marker marks about 1–3 characters a second at 2 mm character height. A desktop fiber laser marks a 10-digit serial number in a few seconds.
Tell us what you need to number
Send a photo of the part, the material, what happens to it after marking, and how many parts you mark an hour. We will reply with one method, one machine and a delivered price.
