Color laser engraving opens up the laser engraving field to a whole new world of possibilities. Whether you want to add some vibrancy to your company logo or print a bold image on your wedding rings, you can make it possible through color laser engraving.
But what exactly is color laser engraving?
Color laser engraving is a laser engraving technology that adds color to engraved objects. This is usually achieved by heating the surface of the material to form an oxide layer after which visible light can be reflected on it. This light is what creates the appearance of color. In some cases, a color dye powder is spread over the object then melted into the engraving using an engraving machine.
You can color engrave a variety of materials including plastics, rubber, coating materials, electroplating materials, engineering plastics, ABS, Pes, PVC, and epoxy resin, acrylics and metals (steel, titanium, transition metals, and chrome plates).
How color laser engraving works
The principle behind laser color engraving is surface oxidation. Scientifically, many material surfaces react in the air to form thin oxide layers. When the surface of a material is heated using a laser beam, it forms a thin oxide film. The actual thickness of this film is achieved by altering the scanning velocity, power, and line spacing. Other essential parameters for the technology include marking direction, marking speed, focal spot diameter, pulse length, and repetition rate.
Once a constant material surface temperature has been maintained, a uniform color can be created. The thin oxide layer will grow in thickness until it forms a thin film effect. This is what determines the reflection of white light and hence the appearance of other colors. A thick oxide layer is beneficial because it protects the material against corrosion and scratching. For acrylic, color laser engraving is achieved through the addition of a color dye powder. This begins with traditional engraving then pressing a special powder on the engraved parts using a laser machine.
Color laser engraving using MOPA fiber
The MOPA (Amazon link), which is an acronym for Master Oscillator Power Amplifier, is a type of laser fiber used in color engraving projects. This machine uses a modulated seed laser that promotes effective pulse parameters while on function. It is also popular for high peak powers and pulsing frequency ranges that are lacking in standard designs. Furthermore, the laser can work in a continuous wave mode.
The MOPA arrangement is possibly the best thing that happened to the world of laser engraving. It allows for better control over peak power and pulse width through its PulseTune functions thereby enhancing high repetition rates at high peak powers. In short, the new MOPA fiber laser allows for separate tuning on varying laser parameters. This process is often optimized for the production of quality colors and a better visual appearance.
Applications of color laser engraving
Adding a burst of color on engraved objects may seem like a new idea but the technology has actually been around for decades. It was introduced as a way to some life to jewelry and craft metalwork. Although the technique didn’t take off at first, it is now quite a sensation. Organizations and individuals now utilize color laser engraving for various purposes including;
- Marketing – e.g. creating product customizations for customers
- Branding – e.g. color marking of a vast collection of products including firearms, bathroom fittings, electronic equipment, automobiles, aircraft, and medical products
- Jewelry – e.g. adding a touch of beauty to watches, jewelry, and craft metal works
- Design – e.g. creating eye-catching designs, graphics, and images on products
These are only a handful of the commercial applications of color laser engraving. There are countless possibilities for a creative mind. Some of the practical ideas of color laser engraving include mobile phone keypad, laptop keyboard, iPhone back logo, TV controller keyboard, plastic translucent keys, etc.
Materials for color laser engraving
Not every material that is ideal for laser engraving is a good fit for color laser engraving. Thankfully, with the constant rise in laser technology, the future looks promising. In the meantime, here are some of the materials that can work with color laser engraving.
Metal, especially stainless steel, is arguably the most widely used material in color laser engraving. Color laser engraving changes the outer layer of the metal and introduces a range of colors on the engraved parts. Raw or untreated metal surfaces are particularly great to work with as you have many colors to choose from. The actual color on the metal depends on the laser frequency, focal distance, speed, and power. Other metals that are color laser engravable include chrome, titanium, and steel. There are four main processing strategies for color laser engraving on metal. These are;
The line-by-line approach produces color in a single line rather than a marked area. The lines are created in uniform widths to ensure the appearance of a uniform color.
- Line overlapping
This is achieved by scanning a spot in a manner that the marking lines overlap. Here, the oxide layer occurs through energy accumulation of two or more lines ultimately creating visible color.
- Cooling and solidification
When using this technique, a high laser velocity is needed so that the surface can be heated uniformly and long enough to create the oxide layer without melting the material.
- Grating with oxide
grating with the oxide is not as common as the other three techniques. In this technique, when re-solidified, each laser pulse creates an equivalent melt pool which results in a diffracting surface of the melted pool.
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Unlike metals, color laser engraving on plastic still has a long way to go. Presently, engraving on plastic is mainly done in essentially the same color family as the mother material, except with light and dark variations. A good example is a blue plastic material that cannot be engraved with yellow, green, or other bold colors. That said, a few shade variations can be made possible where dark plastic materials are altered to a lighter shade or vice versa. Some of the plastic materials that can be color laser engraved include polyethylene plastics, ABS plastics, glass-filled plastics, and other plastics.
Acrylic is one of those metals with endless alteration possibilities. From adding metal discs and foil appliques to enhancing its detail using black dye, there’s a lot you can do to add vibrancy to your acrylic materials. Additionally, acrylic is quite fun and easy to work with since it allows for a good markup and ultimately looks fantastic in the end.
Color laser engraving on acrylic takes on a different angle from the previous materials. It is actually quite straightforward. Once you have your laser engraved parts, all you need to do is fill it with colored paint then squeegee and wipe using a moist porous paint thinner to permanently add color. The new technology, however, uses some form of color dye powder to achieve this. Here, you run the laser after filling your engraved parts with sufficient powder. Be sure to operate at high speed and low power.
Why add color to your engraved objects?
Laser engraving using two colors day in day out can get quite boring because let’s face it: color sells. Even the tiniest burst of color can transform an ordinary product into a breathtaking masterpiece. In this color-oriented society, you stand a better chance by adding some color to your laser engraved objects. Be it your company’s logo, picture, a badge, a humdrum plaque, or any other product on sale, color can dramatically make it spectacular. Your customers will surely appreciate the effort and reward you with massive profits.
If you are getting into laser engraving as a business, you should totally take advantage of the available color laser engraving technologies. Not only will it help your laser engraved products to look prettier but the products will fetch a better price too. Granted, you may not be able to make color laser engraved objects on all materials but you can still make great designs on stainless steel, plastics, and acrylic. As the technology keeps improving, we might soon get laser engravers that can color laser engrave on other materials too.