Marking Stainless Steel Gauge Pins

Machinists frequently use precision ground gauge pins as Go / No-Go indicators during the manufacture of close-tolerance components. Here at Synrad, we use precision gauge pins during tube assembly in the clean room to ensure that our lasers' optical resonators meet exacting quality standards.

Because several different gauge sizes are used in the manufacturing process, our Applications Lab was asked to mark each gauge pin with its corresponding diameter. Our marking setup consisted of a Firestar t-Series 100 W laser, an FH Series marking head, and our WinMark Pro laser marking software. The FH head was equipped with an 80 mm lens that provides a 116-micron (0.005") focused spot with a 0.8 mm (0.032") depth of focus over a 33 mm × 41 mm (1.3" × 1.6") mark field.

We marked 2-mm (0.080") high text on this
stainless steel gauge pin using 100 watts of
power in a cycle time of 0.34 seconds per piece.

A close-up photograph showing the array of
0.015" deep grooves we engraved in a boro-
silicate glass tube using 140 watts of power
at a scan speed of 150 inches per second
after 150 passes.







This microscopic view shows detail of a
0.055" wide groove after engraving the
glass to a depth of 0.015".

Marking Polyimide Labels

High-temperature polyimide labels are commonly used in the circuit board industry where product labeling must withstand high temperatures, cleaning solvents, fluxes, and wave soldering processes. Polyimide labels are also specified for many aerospace and military applications where long-term component temperatures do not exceed 180 °C (356 °F), but short-term temperatures could reach a maximum of 280 °C (536 °F).

The product labeling requirements for this project called for laser-marking a 2D Data Matrix code, a Code 3 of 9 barcode, and an 8-digit human-readable text string. Based on a polyimide label size of 25.4 mm x 6.35 mm (1.0” x 0.25”) and a need to represent only eight characters, we used our WinMark Pro laser marking software to create a 12 × 12 2D code object with an overall size of 3.83 mm (0.1509”), which equates to a single cell size of 12.6 mils (0.32 mm).

We created high-contrast readable text and
barcodes on this high-temperature polyimide
label using just 10 W of CO2 laser power.

Next, we added a Code 3 of 9 barcode sized to a Barcode Height of 2 mm (0.08”) and a Barcode Thick to Thin Ratio of 2.1. For the human-readable text string, we used WinMark’s built-in Simple stroke font to create a text string measuring 1.8 mm (0.07”) high with 0.25 mm (0.01”) of Extra Character Spacing to enhance readability.

To mark the 0.11 mm (0.0044”) thick polyimide label, we set a Power value corresponding to 10 watts, a Resolution value of 300 for text and 2D code objects, and a Resolution of 200 for the Code 3 of 9 barcode. We then set a marking Velocity of 1651 mm/second (65 inches per second—IPS) for the 2D code, 889 mm/sec (35 IPS) for the 1D barcode, and 1143 mm/sec (45 IPS) for the text object.

Our 48 Series 10-watt laser / FH Series marking head combination was equipped with a 125 mm lens that provides a 180-micron (0.007”) focused spot with a 3 mm (0.118”) depth of focus. Using the mark parameters described above, we achieved high-contrast marks on the polyimide labels in an overall cycle time of 0.69 seconds per label. Both 2D and 1D barcodes were scanned and verified using an RVSI CM4000 vision system.