Laser Engraving Tips and Tricks

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Laser Engraving has changed dramatically over the past decade or so. When I began working in this industry, if you wanted to have a laser at your factory or shop you have to have THREE THINGS: Highly Trained Personnel, Patience and very DEEP pockets.

In the past 10-years or so, computing power, solid-state lasers and deployment of systems has brought the prices down significantly, the required skill set to own and operate a system is very low and system maintenance has become seriously simplified.

So, let’s get to the meat of this Article.

Laser MARKING: TIPS and TRICKS

1. First and Foremost, have the correct Wavelength!

The Wavelength of the laser is critical to part marking.

ORGANICS:

For example, Let’s say your primary business is custom firearms. Most people start with a simple CO2 laser having a Wavelength of 10,600nM. These are low-cost, low-barrier systems meant for engraving and marking the ORGANICS. Wood, Paper, Glass and Stone to name a few. A CO2 is a GREAT choice for engraving and marking the Wood Butt Stocks and Polymer Grips, but isn’t going to do much in the way of engraving the metal portions of the firearm.

METALS:

In order to effectively mark and engrave with any depth in metals, we need to change wavelength. Here, the appropriate wavelength for MOST common metals is about 1uM. Why do I say about? Simply put, there is a number of variations for the 1uM laser, commonly clumped together as the ubiquitous “YAG”. In truth, the YAG is the Nd:YAG with a central emission of 1,064nM. But then there is the Nd:YVO4, the Nd:YLF and the mainstream FIBER laser with it’s proprietary glass-doped gain medium. Each of these lasers are 1uM lasers, but have slightly different wavelengths from 1,064nM, 1,057nM, 1,070nM and such. Additionally, each has different pulse characteristics and that can play a major role in the proper selection.

2: Why does Lens Selection matter?

You would be surprised at how many times I have to explain optics to people. It’s a basic and required step in choosing the right tool for the job and there’s a very core component everyone should understand. SPOT SIZE!

SPOT SIZE vs FOCAL LENGTH:

The Spot size of a laser is critical. Let me just repeat that. The Spot size of a laser is critical! Simply put, you need a certain amount of energy to do work. Remember as kids when some of us would take a magnifying glass outside and burn things? Remember how as we found focus, the wood would just start to smolder, and as the spot became smaller and smaller near the focal point the wood would really start to char and burn? And as we went too close, the spot would grow again and the burning stopped? That is a GREAT demonstration of fluence. Fluence is a term which equates in the simplest understanding of Energy for a given Area.

In our example above, the Sun’s energy was fixed (unless a cloud passed by). We adjusted the Energy/Unit of Area by focusing the lens to it’s tightest focus. If you think about a pizza. If you get a Large versus a Small pie, the diameter may double. Let’s say a Large is 20″ diameter and a Small is 10″. But you don’t get twice as much, you actually get quite a bit more because if the diameter doubles, the AREA goes up by a factor of 4!! This is the same for the laser. If we HALF the spot-size we INCREASE the energy density not by twice, but by a factor of 4!!

We’ll continue this and other selection tips in the next article.

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