What gets marked on engine parts
Engine plants mark almost every major part. Cylinder blocks and heads carry a casting code from the foundry and then a machining serial or 2D Data Matrix code (DMC). Crankshafts and connecting rods carry a serial and grade marks for bearing selection. Pistons carry a size grade and an orientation mark so they go into the right bore the right way round.
The grade marks drive selective assembly. A block's main bore grades and a crankshaft's journal grades decide which bearing shells are fitted, and the assembly station reads them from the parts. Connecting rods and caps are machined as a pair and are marked so a cap never ends up on the wrong rod.
A DMC on the block or head ties each machining operation and leak test result to one engine. Vehicle makers rely on that link when they trace a field complaint back to a machine or a shift.
Which laser marking machine suits engine parts
On machined faces of cast iron and aluminium blocks and heads, a fiber laser gives the DMC and serial that camera readers along the machining line need. A 30 to 50 W source is common for laser marking on engine parts, because the code has to survive washing and handling between stations, and a deeper engrave holds up better than a light surface mark.
At the foundry stage the casting surface is rough, with sand residue and scale. Dot pin marking, or a deep laser engrave on a cleaned pad, is the usual approach for the foundry serial, since a shallow laser mark on raw casting skin reads poorly.
Crankshafts and connecting rods are usually forged steel. Fiber marks on machined faces work well, kept clear of journals and fillet radii. Aluminium pistons take a light fiber mark in the area the drawing allows, normally away from the ring grooves and the bowl.
When dot pin marking is the better choice
For the foundry serial on a raw block or head casting, a dot pin mark is usually more dependable than a laser. It reads through sand residue and scale, and it survives shot blasting before the part reaches the machining line.
Setting up the job
In laser marking on engine parts for automated lines, the marker is usually a fixed station on the transfer line. An online laser marking machine mounted over a pallet stop is triggered by the line PLC, and a camera reader after it confirms the code before the part moves on.
Blocks and heads are large and heavy. Put the mark on a machined pad near a datum so the reader always finds it in the same place. Coolant on parts straight from machining spoils marks, so mark after the washer or at least after an air knife.
Grade codes to ISO/IEC 29158 and agree an acceptance grade with your customer. Check codes at the last station that reads them, such as the assembly line, and not only beside the marker, because handling and washing in between can damage a shallow mark. For rod and cap pairs, mark both halves in one cycle while they are still bolted together.
What to check before you buy
- Part list. List every part to be marked with its size and weight, from pistons to blocks, and decide which share one station.
- Process stage. Separate foundry marks on raw castings from machining line marks, since each may need a different method.
- Mark depth. Agree the depth needed to survive washing and handling up to final assembly.
- PLC interface. Confirm the marker accepts triggers and data from your line PLC and reports success or failure back.
- Grade marks. Check the software can take measured grades from the gauging station and mark them as variable data.
- Reader placement. Plan a reader immediately after the marker and another at assembly.
- Coolant and wash. Mark dry parts. Plan an air knife if the marker sits before the washer.
- Extraction. Marking cast iron gives off dust and fumes, so fit extraction at each station.
Laser marking on engine parts in Tamil Nadu
Engine and engine component manufacturing in Tamil Nadu is centred on the vehicle and engine plants in the Sriperumbudur and Oragadam belt and around Hosur, with a large supplier base for castings and forgings. Coimbatore's foundry cluster supplies automotive castings alongside its pump and motor castings, and Chennai's Ambattur and Guindy industrial estates have machine shops serving the automotive supply chain.
NMB Enterprises is based at Poonamallee in Chennai. Engine part suppliers across Tamil Nadu can call or WhatsApp 098417 60722 with photos of the part, marking the intended area on the photo, and a note on the process stage, and get a recommendation for laser marking on engine parts or dot pin as suits the job.