Laser marking comes in two forms: heat marks and laser engraving. Let’s take a closer look at how these two differ.
Heat marks, also known as annealing, is a thermochemical reaction that occurs when a laser applies low heat to a part’s surface. This creates an oxide layer and results in a visible mark. Although there is no depth to the mark because material isn’t displaced, the mark is permanent.
Since there is no material displaced during the annealing process, there are no grooves in the mark where bacteria could potentially grow. It also eliminates the possibility of the mark corroding. Heat marks are commonplace in many industries, including Medical and Aerospace.
As with heat marks, laser engraving occurs when a laser applies heat to the surface of a part, resulting in a permanent mark. The difference is that material is displaced when it is engraved, giving the mark depth and edges that you can feel. Sometimes laser engraving only removes the coating of a surface; this is known as laser etching. Other times, it may go beyond the coating and displace the material of the part itself. Deeper laser engravings can be achieved with a high-wattage laser, though low-wattage lasers can make deep engravings if it makes several passes.
Engraving is ideal for parts that will experience a lot of wear or for parts that have been painted or coated. Automotive, Aerospace, Electronics, Firearms, Packaging, Heavy Construction Equipment and many more industries use laser engraving to identify and track their products.
It’s Shark Week so let’s celebrate by taking this shark vector image and putting it on a magnet with our GeoMARK Pro. We’ll use a 20-watt laser to make a heat mark and then switch over to a 100-watt laser for laser engraving.
As you can see, the laser engraving of the shark left grooves whereas the heat mark made a smooth fill.
It’s important to note that when it comes to marking depth, we’re not talking about depths measured in inches but rather, depths measured in thousandths of an inch. If you ran your finger over the laser engraving of this shark, you could feel the depth of the grooves but it would be difficult to actually see the depth without a close inspection. That said, with a strong enough laser and enough passes, you could get deeper engravings that are easier to see.
Which is better?
As is normally the case when discussing different kinds of marks, one mark isn’t generally better than another. It all depends on your application. As mentioned above, heat marks are great for the medical industry and laser engraving is great for heavy construction. If you’re unsure of what works for you, we offer sample marking to help you decide what kind of marking technology is best for your application.