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All you need to know about metal engraving / etching / marking

Laser aluminum marking

A lot of people are looking for an efficient laser engraving/marking tool.

 

In this post, we will explain all you need to know about laser metal engraving and the difference between making and etching.

 

Now you do not need a new machine – you can simply install the laser emitter on your existing 3D printer / CNC router or XY plotter and be able to engrave / mark / etch at home or at your workshop.

 

Etching vs engraving

Laser engraving vs laser etching

 

Let’s get started.

Thermal conductivity, metal melting temperature, laser pulses.

First of all, you need to know that metals have a high temperature of melting and require high energy pulses to vaporize metal. So actual engraving/marking can be applied if your laser has a pulse mode with the good energy of a single pulse.

 

Once the laser pulse hits the metal it creases a bright flash.

Like this.

Metal flash
This is a shot of a plasma that flies away.

 

Most metals have a melting temperature of 1000C+ (see the appendix table below)

That actually requires high-energy pulses and some average power. In Endurance, we offer 4 watt DPSS laser module that is capable to do laser engraving / marking. 

 

 

Proceed with a fast and secure checkout. Free DHL shipment worldwide. Get your laser in 3-5 days.

Also, metals have high-temperature conductivity that requires a lot of power as well.

Materials thermal conductivity

As you see metals have 100-500 times more heat conductivity than wood, water, or glass.

That means that the temperature spreads inside the metal very quickly.

 

Metal thermal conductivity
Thermal conductivity for some types of metals

Copper, silver, gold and aluminum have the max thermal conductivity that is why most heatsinks are made out of aluminum or copper.

 

To get metal engraving /marking jobs done you need high ultra-short and high energy pulses.

Pulse width can vary 1-150 ns

Pulse energy should be at least 10 uJ

and the average power of the laser should be at least 4 watts.

(that is not necessary but according to our R&D those parameters work the best for fast and accurate metal engraving / marking)

Laser pulse width / average power / repetition rate

 

 

However, to get a metal etching you do not need laser pulses and you may do that with 5-15 watt laser power.

Metal etching is a bit different process and does not need pulses at all. It is more like a chemical reaction adding another element on top. Usually, it is an oxide of the original material.

 

 

Most laser marking machines do not have a lot of power (most of them have 20-50 watt average power output) but they do have pretty good energy in a short laser pulse (5-150 ns).

 

Laser engraving/laser marking is the actual process that removes (vaporize) part of metal from its surface.

High energy pulse heats up the metal creating a hot plasma. That plasma flies away leaving an empty space on its surface.

 

That allows getting in-depth laser engraving and you can watch the video of the process below

 

Some people consider etching the same as marking and engraving but there is a key difference between engraving/marking and the etching process.

Once you etch the metal  – you create an oxide file (oxidation). That oxide film can be thin and not very stable, Usually, it can be removed with acetone or using a solvent.

Usually, metal engraved or marked will remain a lifetime on the material.

Accurate laser engraving / marking

 

For example, you can etch on titanium and stainless steel with low CW power diode lasers. You may that those metals with 5-10 watt CW power output but you can not etch aluminum.

Some metals can be etched with a special engraving paste-like thermal grease, Dry Lube Moly, or Cermark engraving paste.

 

In this video, you see short pulses of laser engraving/marking.

Pulse width is about 7-9 ns and the average laser power is about 10 watt however laser pulse is about 40 uJ

 

In this video, you may see how Dry Lube Moly can be used in a laser etching process

 

However with 15 watt diode (DUOS) laser you can etch without any paste on titanium, steel, stainless steel

 

Another important thing is that metals have different wavelength reflections and absorption spectrums.

Absorption wavelength spectrum for different materials: glass, metal and others.

 

Diode lasers and DPSS laser can be installed almost on any 3D printer / CNC machine or engraving plotter.

 

A 10-watt DPSS laser module is installed on a CNC router.

Endurance 10 watt DPSS laser on CNC router

However, the fastest speed of engraving can be reached if the laser is installed on a galvoscanner (galvo)

An Endurance DIY marking machine with 4 / 10 / 30 / 50 watt DPSS / Fiber (Raycus) laser eddmiters with a Sino Galvo head.

 

Usually, industrial laser metal marking takes a few seconds to make a company name or a logo

 

An interesting fact is that with different types of lases you may do a color metal engraving (called tint colors)

Color metal engraving

 

The basic theory is that different laser pulses (energy), different power can create different colors on metallic surfaces.

Usually, those laser markers are very expensive and require adjustable energy pulses and adjustable laser power.

However, you can still get different colors by changing laser engraving speed, laser power, laser beam focusing and amount of repeats and we describe it in detail in the following article >>>

What you can do with different laser types

Power
Diode lasers<5 watt5-10 watt10-15 watt
Stainless steeletchingetching
Steeletching
Copperwith thermal grease / dry lube molywith thermal grease / dry lube moly
Brasswith thermal grease / dry lube molywith thermal grease / dry lube moly
Titaniumetchingetchingetching
Anodized aluminumetchingetching
Painted aluminumRemoving paintRemoving paintRemoving paint
Polished aluminum
Power
Co2 laser<40 watt40-80 watt80-150 watt
Stainless steeletchingetching
Steeletchingetching
Copperwith thermal grease / dry lube molywith thermal grease / dry lube moly
Brasswith thermal grease / dry lube molywith thermal grease / dry lube moly
Titaniumetchingetchingetching
Anodized aluminumetchingetching
Painted aluminumRemoving paintRemoving paintRemoving paint
Polished aluminum

 

 

Power
DPSS/Fiber laser4-10 watt10-30 watt30-50 watt
Stainless steelengraving/markingengraving/markingengraving/marking
Steelengraving/markingengraving/markingengraving/marking
Copperengraving/markingengraving/markingengraving/marking
Brassengraving/markingengraving/markingengraving/marking
Titaniumengraving/markingengraving/markingengraving/marking
Anodized aluminumengraving/markingengraving/markingengraving/marking
Painted aluminumengraving/markingengraving/markingengraving/marking
Polished aluminumengraving/markingengraving/markingengraving/marking

Conclusion

It is obvious the with lasers you can do an effective laser engraving / marking / etching.

Diode lasers and Co2 laser can do metal etching and DPSS and fiber lasers can do metal engraving / marking

 

If you have any more questions – you are welcome to ask in our Livechat!

 

Appendix: Metal melting temperature

METAL

MELTING POINT

(oC)(oF)
Admiralty Brass900 – 9401650 – 1720
Aluminum6601220
Aluminum Alloy463 – 671865 – 1240
Aluminum Bronze600 – 6551190 – 1215
Babbitt249480
Beryllium12852345
Beryllium Copper865 – 9551587 – 1750
Bismuth271.4520.5
Brass, Red10001832
Brass, Yellow9301710
Cadmium321610
Chromium18603380
Cobalt14952723
Copper10841983
Gold, 24K Pure10631945
Hastelloy C1320 – 13502410 – 2460
Inconel1390 – 14252540 – 2600
Incoloy1390 – 14252540 – 2600
Iron, Wrought1482 – 15932700 – 2900
Iron, Gray Cast1127 – 12042060 – 2200
Iron, Ductile11492100
Lead327.5621
Magnesium6501200
Magnesium Alloy349 – 649660 – 1200
Manganese12442271
Manganese bronze865 – 8901590 – 1630
Mercury-38.86-37.95
Molybdenum26204750
Monel1300 – 13502370 – 2460
Nickel14532647
Niobium (Columbium)24704473
Palladium15552831
Phosphorus44111
Platinum17703220
Red Brass990 – 10251810 – 1880
Rhenium31865767
Rhodium19653569
Selenium217423
Silicon14112572
Silver, Pure9611761
Silver, Sterling8931640
Carbon Steel1425 – 15402600 – 2800
Stainless Steel15102750
Tantalum29805400
Thorium17503180
Tin232449.4
Titanium16703040
Tungsten34006150
Yellow Brass905 – 9321660 – 1710
Zinc419.5787

 

Learn more about wiring the laser to  CNC machine and different 3D printers

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