What gets marked on gears
Gears for gearboxes and axles are usually marked with a part number and a heat-treatment batch or furnace load number. Transmission plants increasingly add a 2D Data Matrix code (DMC) with a unique serial, so each gear can be traced from the forged blank through hobbing, heat treatment, grinding and final inspection.
The reason is failure analysis. If gears from one lot show pitting or a tooth fracture in the field, the plant needs to know the forging lot and the furnace load behind them. A heat code alone narrows the search to a batch, while a part-level DMC narrows it to a single gear and its own gauge readings.
Marks always go on non-functional surfaces, usually the gear face or the hub. Tooth flanks and bearing journals are never marked.
Which laser marking machine suits gears
A fiber laser is the standard tool for laser marking on gears. On hardened and ground faces it gives a dark, high-contrast mark that camera readers handle well. Hardness itself is not a problem for the laser. What matters is surface finish, and whether the mark will survive the process steps still to come.
Timing is the main decision. A shallow laser mark made on a soft blank before carburising usually fades in the scale that forms during heat treatment, and shot blasting or grinding then removes what is left. There are two common answers. Mark after heat treatment and finishing, which gives the best contrast. Or, if traceability must start at the soft stage, put a deep fiber engrave or a dot pin mark on the blank so it survives carburising and quenching, and add the final DMC after grinding.
Laser heat input is small but not zero. Most gear makers accept marks on faces away from the teeth. If your customer limits surface tempering on hardened faces, mark a sample and have your metallurgy lab check it before releasing the process.
When dot pin marking is the better choice
If a gear must be identified from the soft blank stage, a dot pin mark on the blank usually survives carburising and shot blasting better than a shallow laser mark. Many plants use dot pin for the early process mark and a fiber laser for the final DMC.
Setting up the job
For laser marking on gears in volume, fixturing comes first. Gears are round with a bore, so a locating mandrel or expanding arbor on the marking table puts each gear in the same place. Text can be laid out on an arc around the face, and the DMC goes on the widest flat band between the bore chamfer and the tooth root.
Ground faces are close to a mirror finish and can confuse readers. A dark oxide mark usually reads better on them than a shallow bright engrave. Set the DMC cell size to suit the reader distance and verify codes to ISO/IEC 29158, checking samples from each furnace load when the process is new.
In a transmission machining line, the On-line Fiber Laser fixed over a conveyor or a Desktop Fiber Laser fed by an operator can mark gears after the final wash, with a reader checking each code before the gear moves on. Parts must be dry, since washer residue on the face spoils the mark.
What to check before you buy
- Process stage. Decide whether the first mark goes on the soft blank or after heat treatment. That decides whether a deep engrave or a dot pin mark is needed.
- Mark location. Agree the mark area with the gear drawing owner so it stays clear of teeth and datum faces.
- Face finish. Run trials on your actual ground and shot-blasted faces, since each gives different contrast.
- Code size. Measure the flat band available on your smallest gear and confirm a readable DMC fits inside it.
- Furnace records. Check the software can include the furnace load or heat code as a variable field.
- Part range. List bore sizes and outside diameters so the fixture can be adjustable rather than one mandrel per gear.
- Metallurgy approval. Plan a metallurgical check of a marked sample if your customer specifies limits on hardened surfaces.
- Reader check. Fit a reader after the marker so a poor code is caught at once instead of at assembly.
Laser marking on gears in Tamil Nadu
Gear and transmission component production in Tamil Nadu sits close to the vehicle plants, in the Sriperumbudur and Oragadam belt near Chennai and around Hosur, a major centre for two-wheeler and commercial vehicle manufacturing and their suppliers. Coimbatore has gear cutting shops serving textile machinery and pump makers, and Chennai's Ambattur and Guindy estates have job shops that hob and grind gears for local customers.
NMB Enterprises is based at Poonamallee in Chennai. Gear makers across Tamil Nadu can call or WhatsApp 098417 60722 with photos of the gear and a note on the material and the stage at which marking is planned, and get a recommendation for laser marking on gears in their process.