Sometimes, we get confused about the metal annealing & engraving.
Laser annealing is a metal marking process of placing any designs or patterns on metal by changing the metal properties, not melting or removing layers. The main difference between annealing and engraving is that the engraving process involves melting or removing a layer of the metal and the annealing only changes metal properties.
In this article, we will clear your thoughts on metal annealing and engraving using examples and pictures.
What is laser color annealing?
In the annealing process, a laser beam heavily heats the upper layer of the metal which causes sudden changes of the metal atoms. Color annealing involves heating the metal at different temperatures that give the upper layer a colored pattern.
Normally, annealing is applied to Marking identification marks (serial numbers, brand name, date, etc) on the metal parts. The same process can also help to generate color engravings in the metal workpiece.
What are the advantages of laser annealing?
In summary, the core advantages of laser annealing include precision, fast processing time, environment-friendliness, and maximum compatibility.
The main advantage of laser annealing is that the process is purely contactless. Since the laser does not establish any contact with the material, it does not need any pigment to place any markings on the metal. This is why laser annealing is treated as an environmental concept.
Moreover, through laser annealing, the metal workpiece can be laser marked either with the designs or any specific pattern that makes us add value to the metal items.
For example, companies are now expanding their marketing budgets on stainless steel marking rather than incurring the costs of printed gift material. Alternatively, the laser annealing process helped an entire industry to grow. As a reference, there is a study that concluded that 66% of people are willing to pay premium prices for sustainable products and the metal marking is purely sustainable.
Additionally, metal marking through annealing ensures maximum precision. Remember, this is the only non-contact way of placing QR codes on the metal water bottles!
Lastly, metal marking is the fastest way of placing patterns on metal surfaces which allows the business owners to earn more utilizing their machinery at best.
Does annealing change color?
Yes, laser annealing changes the metal atoms through heavy heat and oxidization that gives a portion of the metal a separate appearance.
This is often referred to as the metal color engraving where most of us get confused.
However, annealing cannot bring vibrant colors like the printers because the color here is just a reaction of the metal properties alteration.
For stainless steel, for example, the colors typically observed (in order of increasing temperature) are pale yellow, gold, bronze, purple, blue, light blue, and dark blue.
So, you cannot make a natural picture with the annealing but you can surely engrave a photo or place a scannable QR on metal with this process.
Which steel can you laser anneal?
Laser annealing can be applied to several types of steel. Here’s a list of metal types that can be laser-marked using an annealing technique.
- Stainless steel
- Carbon steel
- Alloy steel
- Tool steel
- High-speed steel
Notably, annealing is the same process as how gold jewelry is engraved. So, you can apply this technique on any type of metal workpiece where the change in heavily heated metal properties can result in a different contrast.
Here’s a stainless steel annealing example done with an infrared laser.
How does laser annealing differ from engraving?
In a nutshell, laser engraving involves melting a layer of metal whereas annealing refers to changing metal properties to create the pattern or color.
So, if you can feel any metal engraving with fingers and notice depth then it is an engraving. Alternatively, you can see or slightly feel the metal marking done through annealing but there would not be any layer melted or burnt.
Below is a picture that illustrates the basic principles of annealing & engraving.
As you can see in the above picture, laser marking (performed through annealing) is not noticed towards any meeting/cutting of materials.
Another difference is the ability to bring color. Annealing can bring color by changing the metal properties whereas engraving cannot make colors. This is why people use MOPA fiber lasers for color engraving.
Additionally, the engraving is widely used for crafting purposes whereas the metal marking can only help with just marking the metal with some texts or patterns.
Annealing takes comparably less time than engraving since the engravers need to melt part of the workpiece which takes a bit of time.
Can you do annealing & engraving with the same laser machine?
Yes, this is possible. You may use fiber lasers that can engrave and anneal the metal.
You may also use the high-power CO2 lasers for annealing but CO2 lasers are not often used for this purpose since they generate powerful laser waves and the metal pieces reflect the laser beam in the opposite direction.
You may use the combination of (diode + infrared lasers) which effectively engraves and marks metal with the same machine.
Usually, fiber lasers are used for industrial purposes. You may take the example of Toyota which needs to mark all of its car parts with serial numbers. Whereas the other lasers can be used for crafting purposes.
Laser annealing is a straight way of applying a powerful laser beam (at 1090 nm wavelength) to alter metal properties and visualize a portion of it differently. Earlier, it was used by industrial manufacturers but nowadays it is commonly used mainly because of the easy availability of infrared lasers.