Coin Etching Process on 60W MOPA Laser (OMG-X)

I wanted to share the coin etching process I follow on my 60W MOPA laser (OMG-X). Some may find it useful—others, maybe not—but this is what works for me. — Grant Hiebert

Step 1: Centering the Coin

The most important part for me is ensuring the etching is perfectly centered. There’s nothing worse than a coin that “missed the middle.” Take your time to locate the exact center.

My approach:

1. Run 2 passes of a deep cleaning layer to prepare the surface.
   
   • Speed: 2000 mm/s
   • Power: 90%
   • Frequency: 80 kHz
   • Q Pulse: 200
   • Line interval: 0.13 mm

This cleans the surface and ensures it’s ready for the etching process.

For more detailed guidance on Fiber Laser Settings & Parameters, you can check this page.

Step 2: Initial Etching Pass & Alignment Check

I start the etching process but pause after the first pass to inspect if it’s centered.

• If the image is off-center:
  
  1. Correct the position.
  2. Run the deep cleaning layer again to resurface the coin.
  3. Restart the etching pass.

I repeat this cycle until I’m confident the etching is perfectly centered.

Step 3: Etching Layers

Once centered, I perform the main etching process:

Etching settings:

• Speed: 2000 mm/s
• Power: 80%
• Frequency: 45 kHz
• Q Pulse: 200
• Line interval: 0.045 mm

Layer cleanup: Every 10 layers, I perform a quick cleanup:

• Speed: 3000 mm/s
• Power: 20%
• Frequency: 100 kHz
• Q Pulse: 200
• Line interval: 0.045 mm

I aim to stretch the histogram of the greyscale depth map to use the full 256-bit range and then etch 256 layers. This method seems logical to me, though going slightly more or fewer layers probably doesn’t make a huge difference.

Step 4: Coin Flip & Repeat

After finishing the first side:

1. Run 2 passes of the deep cleaning layer.
2. Flip the coin.
3. Repeat all the same steps for the other side.

By following these steps, I ensure a clean, precise, and centered etch every time.