What gets marked on gauges
A plug or ring gauge usually carries its nominal size, the tolerance class (for example H7, or 6H for a thread), the GO or NO GO end, the maker's name and a serial number. Snap gauges carry the same data on the frame. Calibration labs and in-house quality rooms add an identification number to every gauge so that each calibration certificate can be tied to one physical instrument, and many plants now add a small QR or Data Matrix code that opens the gauge's calibration history in their software.
Measuring instruments add a second kind of mark: graduations. Steel rules, vernier scales, caliper beams and depth gauges need fine lines and numbers placed accurately along their length. A laser is good at this because line position comes from the software and the scanner calibration rather than from a mechanical dividing setup, and line width can be held very fine.
Which laser marking machine suits gauges
For laser marking on gauges, a fiber laser is the usual choice. Gauges are commonly made of hardened tool steel, sometimes chrome plated or tipped with tungsten carbide, and a fiber laser marks these surfaces without any contact. That avoids the main risk of stamping or dot pin marking on a hardened gauge, where impact can raise a burr or disturb a finished, lapped surface. A dark oxide mark is often enough on the handle of a plug gauge, while a slightly engraved mark lasts longer on gauges that are handled daily with oily hands and wiped with solvent.
On stainless steel rules and caliper beams, a MOPA fiber laser gives sharp black graduations with little heat spread, which keeps thin scales flat and small numbers crisp. Chrome plated surfaces also mark well, but trial the settings so the mark does not cut through the plating into the base steel, where it could later stain. CO₂ lasers do not mark bare metal and have no role on metal gauges, though a UV laser can mark plastic gauge handles and storage cases.
When electrochemical etching is still used
Many gauge rooms still mark occasional gauges by electrochemical etching through a stencil. It works on hardened steel without heat, but each new text needs a new stencil and mark quality depends on the operator. Once gauge marking becomes regular work, a fiber laser is the more practical tool.
Setting up the job
Gauges are small and mostly cylindrical, so a V-block or a collet fixture that holds the plug gauge handle at a fixed height is the first thing to make. Text on the flat face of a ring gauge is easy; text along a plug handle may need a rotary attachment or a short text block placed on a machined flat. Good laser marking on gauges never touches the gauging diameters or lapped faces.
For scales, the main question is length. A galvo marker covers a limited field, often around 100 x 100 mm, so a 300 mm rule needs either a long lens with lower detail or a motorised axis that moves the scale and marks graduations section by section. Section marking has to be checked against a reference scale, because any error at the joints shows up as a step in the line spacing. For calibration ID marking on existing gauges, prepare a template per gauge type so the operator only enters the ID number, and read each code back with a scanner before the gauge returns to the rack.
What to check before you buy
- Hardness and plating. List the gauge materials, especially chrome plated and carbide-tipped gauges, and get each one trial marked.
- Smallest text. Check the smallest character height the machine holds cleanly, since thread gauge data often has to fit on a narrow handle.
- Graduation accuracy. For scales and caliper beams, ask how line spacing is verified across the full length and how section joints are handled.
- Field and lens. Match the lens field to your longest single mark; a smaller field gives finer detail.
- Legibility under oil. Gauges are handled with oily fingers and cleaned often, so check that trial marks still read after a solvent wipe.
- Calibration codes. If you use calibration management software, confirm the marker can produce QR or Data Matrix codes from your ID list.
- Holding fixtures. Plan V-blocks and collets for each gauge size range before the machine arrives.
Laser marking on gauges in Tamil Nadu
Gauge use in Tamil Nadu follows its machining base. Component suppliers in the Ambattur and Guindy industrial estates, the auto belt around Sriperumbudur and Hosur, Coimbatore's pump and motor shops and BHEL-linked fabricators around Trichy all keep gauge rooms, and each needs gauges with readable, lasting identification. Laser marking on gauges is useful both to gauge makers who mark new gauges in batches and to quality teams that re-mark worn or unlabelled gauges during a calibration drive.
NMB Enterprises in Poonamallee, Chennai, is an authorised distributor of IndoForeign Technologies fiber laser systems. Send photos of your gauges with their sizes and the text you need by WhatsApp to 098417 60722, or call the same number, to discuss a suitable marker.