Metal Engraving and Laser Engraving Difference

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Metal Engraving and Laser Engraving Difference

Dec 05, 2022

Laser engraving refers to placing information onto surfaces of components by evidently penetrating the surface of the material. On the other hand, laser markinginvolves putting legible information onto parts’ surfaces with little or no penetration.

Laser engraving on metal changes the structure of the metal surface as it removes material from it. By doing this, the technique causes lasting high-contrast marks that are easy to identify. In contrast, laser marking uses a concentrated laser beam to change the workpiece’s surface. The four common laser marking methods include foaming, coloring, carbon migration, and annealing.

Many manufacturers use galvanometer or fiber laser systems to mark bare metals and enhanced plastics. These lasers possess unidentical wavelengths to CO2 lasers that permit marking raw metals with the aid of a metal marking agent. While manufacturers often use laser engraving and marking interchangeably, they are different.

What Kind Of Metal Can Be Engraved?

Different engraving processes work better on different kinds of metal. However, it is essential to note that each metal has unique features that make it suitable for certain applications. While aluminum is the popular and commonly engraved metal, manufacturers also carry out engraving on many other metals. The following are the most commonly engraved metals:

1. Aluminum

Anodized or coated aluminum is a good material for making trophies and plaques. Machining grade aluminum is suitable for creating control panels, industrial applications, and interior and exterior signage. Permanent and high-contrasting engravings can be made on all types of aluminum, ranging from raw aluminum to aluminum and coated aluminum.

This metal works perfectly with various engraving technologies, including laser engraving and rotary engraving machines. Consequently, getting deep aesthetic engravings on aluminum is possible. Moreover, laser engraved aluminum parts are resistant to high temperatures and other surface treatments like shot blasting.

2. Brass

“Engravers brass” is a soft and readily available metal for engraving. Commercial brass is unusually thick and hard to engrave. For deep engraving, it is best to use brass with a thickness of 0.040 to 0.060 inches. This type of metal is best paint-filled to get high-quality contrast between the background and the engraved feature.

3. Stainless Steel

Stainless steel has many benefits, even though it is much harder to engrave. It is moisture-resistant, corrosion-resistant, and very durable. A collet spindle is a primary tool required to cut stainless steel. Collect spindles with a split collet delivers deeper cuts due to its extra rigidity and produces much lesser cut chippings.

Laser engraving is sometimes not suitable for cutting stainless steel because its laser may remove a vital protective layer. Therefore, manufacturers use laser annealing as the ideal substitute.

4. Silver, Gold, and Pewter

These are soft metals that are pretty easy to cut. They are the perfect material for making gift items in most engraving applications like the personalization of jewelry. Diamond-drag engraving provides the best results working with these materials. You can make deep cuts on these materials with the same tools used to cut brass. In most cases, you do not need cutting fluids to cut silver, gold, or pewter.

Laser marking steps

Cubes of various metals (Source: Educational Innovations Inc.)

Step 1: Preparing the Design

  1. The first thing to do is create the image you’re going to etch on the metal. Regardless of whether this is a photo or a vector image, it should be black and white or grayscale (if your laser supports it). This will give you an insight into how it will look after etching.

    • A rule of thumb: If it doesn’t look good on the screen, it won’t look good on the metal either.

  2. Scale the image to the desired size. Note that, if you’re etching on a non-planar surface, some image stretching may be required.

  3. Save your work in a format that your laser’s software will accept.

Step 2: Cleaning

  1. Clean your metal piece thoroughly using rubbing alcohol and a soft cloth.

    • Remove all dust and grease from the surface.

  2. If corrosion or rust has formed on the metal surface, use some fine-grit sandpaper to remove it.

    • Some metals don’t rust but do form oxides on the surface. For example, copper will oxidize and form a green patina, and aluminum will also oxidize and form a film on the surface. Regular, plain carbon steel will rust.

Dust and grease will interfere with the focus of the laser, while metal oxides and rust usually have a much higher melting temperature than pure metal. If not properly cleaned, these formations will interfere with the etching process and give you poor quality.

It would be a good idea to wear gloves during the cleaning and preparation process so that the oils and grease from your hands don’t contaminate the metal’s surface.

Step 3: Applying the Spray

  1. Leave your metal piece a couple of minutes to dry before applying the spray. Just before application, again ensure that the surface is perfectly clean.

  2. Using some masking tape, mark the borders of the surface you plan to etch. Apply etching spray evenly on the metal surface. If you’re using dry lube, spray two or three layers, leaving each time to dry before applying the next one.

Some sprays will give better results than others. For example, you can etch stainless steel with dry lube and get good results, but in order to etch aluminum, you should use something like markSolid 114 or equivalent. In either case, it’s a good idea to do some tests before etching the real thing.

Some laser-etched metal cups (Source: The Laser People via Etsy)

Step 4: Adjusting the Focus

  1. Power on your machine and prepare it for etching. Make sure you’re wearing the proper safety glasses!

  2. Put your metal part in the machine and make sure the height of the laser is properly adjusted.

  3. Tune your laser’s focus.

If you’re going to laser etch a flat piece of metal, everything is straightforward, so you can adjust the laser focus as usual.

The tricky part is if you’re etching a curved surface, like a pot or a cup. In that case, you should find the lowest and the highest points, and adjust the focus in the middle. This step will require some trial and error on your side to figure out the best focus for your machine.

Tip: Adjust the position of the metal piece you’ll etch and add some markers in the machine so that you can put back your piece in exactly the same place in the event that you need to remove it again.

If you’re planning to laser etch round objects, it’s worth considering the purchase of a rotary attachment. It’ll make your life much easier, and you’ll get much better laser etching quality.

Step 5: Etching

  1. Load your file from Step 1 into your laser’s control software.

  2. As a starting point, you should set the maximum power and a low speed for the best results.

    • It’ll likely take some trial and error to find the best setup for your machine and metal.

  3. If you’re not happy with the first etching, it’s possible your laser isn’t powerful enough.

    • If this is the case, try running the same file two or three times in the same place.

Step 6: Finishing Up

  1. When the laser is done, remove your metal piece from the machine and clean it.

    • You can use the rubbing alcohol and soft cloth from earlier to remove unused spray and other residues from the metal piece.

    • Aluminum and copper may be more difficult to etch. If you’re concerned about the durability of the markings, you can apply a layer of sealant for protection. (This isn’t a bad idea for easily oxidized metals.)

Materials you should not process with a laser

There are some materials you should not engrave or cut with a laser becuase of their chemical make-up. Processing these materials creates dangerous gases or dust. These materials include:

  • Leather and artificial leather that contains chromium (VI)

  • Carbon fibers (Carbon)

  • Polyvinyl chloride (PVC)

  • Polyvinyl butyrale (PVB)

  • Polytetrafluoroethylenes (PTFE /Teflon)

  • Beryllium oxide

  • Any materials containing halogens (fluorine, chlorine, bromine, iodine and astatine), epoxy or phenolic resins

Care should be taken with the following materials:

  • Manganese

  • Chromium

  • Nickel

  • Cobalt

  • Copper

  • Lead

Caution with the addition of "flame-retardant"

Be especially careful when processing "flame-retardant" materials because they often include of bromine. For flame-retardant materials, it is best to ask the manufacturer about the exact ingredients.

Why are these materials unsuitable for laser engraving and cutting?

If the aforementioned materials are laser engraved or laser cut, dusts or gases may be produced that endanger the laser user or the functionality of the laser machine. For this reason, we do not recommend using these materials.

Why choose laser marking?

1.  It’s Versatile

A huge reason why lasers have become the go-to for manufacturers is because of the versatility of laser marking machines. Parts or products might be tagged with a variety of materials. Lasers have the capability to mark virtually any surface that might be utilized as a barcode tag, including:

  • Stainless Steel

  • Brass

  • Titanium

  • Aluminum

Not only can lasers mark a variety of materials, but they can also mark curved surfaces and can be customized to mark the largest parts down to the smallest with intricate detail. Other marking devices like inkjet or dot peens are not capable of marking unique parts while maintaining a high-quality level of contrast.

2.  It’s Cost Effective

Nobody likes wasting time or money. When it comes to the automotiveor aerospace industry, for example, parts need to be identified immediately in the instance of a recall or part failure. The ability to quickly obtain critical information is of the essence, and laser marking ensures that parts won’t need to be re-marked or replaced in the future, saving money for manufacturers.

Laser marking machines are also capable of barcoding metal parts in bulk, again proving themselves to be the superior choice.

3.  It’s Durable

Not only does the material of a component need to withstand harsh environments, but so does the part’s etched barcode. Markings need to be legible for their entire life cycle, but oftentimes this means withstanding repeated exposure to chemicals, the outdoors,  and temperatures of up to 1200° F.

These extreme conditions eliminate most marking devices from contention, but laser etched barcodesstand the test every time.

4.  It’s High Quality

Some other methods of marking can withstand extreme conditions. Take the dot peen machine. This machine stamps dots into metal to create codes, but the nature of the markings means the level of legibility suffers. Laser marked barcodes can be read quickly by machine, ensuring greater efficiency in many industries.

Laser barcode engraversensure that marks will maintain consistently high levels of contrast throughout the part’s life. The accuracy of laser markings is unmatched and is why most manufacturers won’t bother with anything less.

How Long Does Laser Engraving Take?

Laser engraving typically takes from 5 seconds to a couple of hours. The time it takes to engrave metal depends on the complexity of the design, image, or text to be engraved, material type, and the laser’s power capacity.

Will an Engraving Wear Off Eventually?

Engravings are often permanent, and removing them is often near impossible. This is because the laser engraving machine cuts into the object’s surface, not printing on its surface. However, it is possible that an engraving can be eroded after a long time. In some rare cases, a laser engraved metal may require refinishing.

If you’re interested in learning more about lasers and their amazing capabilities in projects big or small, contact us today!