What gets marked on metal parts
Most marks on metal parts carry identity rather than decoration: a part number, a drawing revision, a heat or batch number and, more and more often, a serial number or a 2D Data Matrix code that links the part to its inspection record. Automotive and engineering customers commonly ask suppliers for part-level traceability, so that if a lot fails in the field the supplier can isolate it by date, shift, machine or raw material heat.
Laser marking on metal parts suits this work because it needs no consumables such as ink or stencils, and the content can change for every part from a spreadsheet or a PLC signal. The mark can also be placed in small, awkward areas on a turned shaft, a flange face or the web of a pressing where a label or a hand stamp would not fit.
Which laser marking machine suits metal parts
For most laser marking on metal parts the answer is a fiber laser at 1064 nm. On carbon steel and alloy steel it gives a dark oxide mark or a shallow engraving, and with more passes it can engrave deep enough to survive light shot blasting. On stainless steel it can make a black annealing mark that sits under the surface with no material removed, which suits parts that must not be roughened. Plain aluminium marks as an engraved grey or white mark, and on anodised aluminium the laser removes the dyed layer to show a bright mark. Brass and copper reflect more of the beam, so they need correct focus and parameters, but a fiber marker in the usual 20 to 50 W range handles text and codes on them.
A MOPA fiber laser is worth choosing when the shop works a lot on stainless steel and anodised aluminium. Because it can vary pulse width, it can make dark marks on anodised aluminium and colour marks on stainless steel, with less heat effect on thin parts. On plated or painted parts, any fiber laser removes the coating to expose the metal, which gives good contrast, but the exposed spot loses its coating protection, so check whether the part will face a corrosive environment.
A CO₂ laser does not mark bare metal and is not a choice here. For castings, forgings and parts that will be painted after marking, a dot pin marker is often the better tool, as the note below explains.
When dot pin marking is the better choice
Dot pin marking makes a physical indentation, so it reads on rough castings, forgings and oily surfaces where a laser mark may lack contrast. It also survives later painting or coating better than a surface laser mark. NMB's Compact Dot Pin Marker and Pneumatic Marking System suit such parts.
Setting up the job
Repeatability starts with the fixture. A simple nest or V-block that puts every part at the same height keeps the mark in focus, because a galvo marker has a limited depth of focus and a shaft sitting a millimetre lower will give a weaker mark. Round parts can be marked on the flat of a shoulder, or turned on a rotary attachment when text has to run around the diameter. The standard field is often around 100 x 100 mm, which covers most turned and machined parts; larger lenses cover a bigger area with lower detail.
Decide early whether the mark is a surface mark or an engraving. A dark surface mark is fast and fine for text and codes on faces that will not be machined again, while an engraving takes longer per part but survives later deburring or blasting. If a Data Matrix code is part of the customer requirement, plan the cell size to suit the reader and check codes with a verifier that grades to ISO/IEC 29158, the grading method for direct part marks.
What to check before you buy
- Material match. List every metal and finish you mark, including plated, blackened and anodised parts, and send real samples for a trial before choosing between a standard fiber and a MOPA source.
- Mark depth. State whether the mark must survive blasting, tumbling, painting or heat treatment, because that decides engraving depth and cycle time.
- Field size and lens. Measure the largest marking area on your parts. A 100 x 100 mm field suits most components, while flange faces and plates may need a larger lens.
- Code requirements. If your customer asks for Data Matrix or QR codes, confirm the software generates them with serial numbers and that your reader decodes them reliably.
- Data link. Ask how the software imports data from Excel or your ERP and whether it accepts I/O signals from a PLC.
- Dust and fumes. Engraving steel and stripping coatings produce fine dust, so plan an extractor near the marking head.
Laser marking on metal parts in Tamil Nadu
Tamil Nadu has a deep base of metal component work. The Ambattur and Guindy industrial estates in Chennai have many machine shops and press shops supplying larger plants, and the automotive and component belt around Sriperumbudur, Oragadam and Hosur draws heavily on forged and machined parts. Coimbatore's pump and motor makers machine shafts and impellers in large numbers, while fabrication shops around Trichy handle work linked to BHEL's supply chain. In all of these places, laser marking on metal parts is usually driven by customer traceability requirements rather than by appearance.
NMB Enterprises is based at Poonamallee, Chennai, and is an authorised distributor of IndoForeign Technologies laser systems. Buyers anywhere in Tamil Nadu can call or WhatsApp 098417 60722 and share photos of the part along with the metal, its finish and the text or code they need. NMB will then suggest a suitable machine from its product range.