Engraving is a mark where material is ablated or meltedand recast to create depth in the material. Metals, ceramics,and certain types of plastics can be engraved with thelaser. The power density of the laser beam is so intense
that the material partially vaporizes, developing a colorlessimpression in the material. Oxides may develop in theengraving causing the mark to be more visible. Materialremoval almost always results in debris produced, whichcan be beneficial in creating contrast or detrimental byobscuring the readability and appearance of the mark ordepositing unacceptable debris on sensitive parts such aselectronics. Engraving is typically done at high powerdensities and high peak power (low frequency). Etching is described as modifying the surface of thematerial to create a minimal depth mark with some
texture. Laser etching can be compared to a brushedor sandblasted type finish. This mark is typically createdusing high power densities and mid to high frequencies
and high writing speed. with a wide variety of images—from the simplest texts,symbols, and logos to photographs, bar codes, and high-precision scales. It also applies customized graphic designs.After an artwork file is entered and positioned, the laser isapplied to the keycap and/or
keyboard. The key or keyboardabsorbs the beam in the form of intense, localized heatand is subsequently burned or melted by the beam. A
programmable Z-axis allows the laser to mark complexobjects by perfecting the angle. Advanced Input Systems’manufacturing engineering team is versed at applying theright angle fit for your specific application. Foaming (only possible with particular plastics) is describedas the process where the laser beam melts the plasticlocally, creating small blowholes that occlude when thematerial cools. A raised mark is produced on whichincident light is reflected diffusely. This creates contrast
to the base material. Annealing (tempering) is described as a surface heatingbelow melting point, which causes an oxidizing effect onsteels, titanium, and some other metals— creating a blackmark with virtually no raised material, no depth, and no
debris. Annealing is done at lower power densities andslow writing speed to build up the heat necessary withengraving the material.
Laser-Marking Technology - 54730 Mark Functions and Types
For all intents and purposes, the laser beam is the catalyst.The laser beam is focused on the material for marking,and the interaction with the surface produces a change
in the material. The change can be related to either coloror material removal, which is defined by type of themarking function.Marking functions are defined by three main parameters:1) writing speed, 2) lamp current, which defines the laser
power, and 3) the pulse frequency of the beam. These
three parameters are interrelated such that the samemark can be produced with a variety of settings bymaintaining a linear increase in speed, power, and
frequency. The absorbed quantity of laser light governsthe ability to effectively heat or vaporize the material atthe surface. Determining the ultimate combination of lampcurrent, pulse rate, and beam velocity for your specificapplication is crucial in the appearance of your input device.The right sequence can improve the quality and attrac-
tiveness of your product. Mark type dependant, laserscan produce impressions that are waterproof, fade proof,non-aging, and highly resistant to chemicals, solvents,
fuels, oils, and grease. Keys of various colors can be markedin gray scales using specially formulated additives andcompounds in the base material. Color legends can also
be marked using these same compounds. For example,black keys can be marked to create a white legend.The many different effects that can be created on variousmaterials with the laser are called “mark types.” By varyingthe process parameters, an alteration of the surface
treatment depth is obtained. Choosing the right markfor your specific application and environment are crucial
elements to the look, touch, and protection of your inputdevice. Mark types are defined below. Ablation (removal) is described as removing a coating ofink/paint, plating, or insulation from a substrate material.
Usually it is desirable to remove the material withoutimpacting the substrate. Many paints ablate easily,however the color is an important factor to consider
when selecting ablation as a marking function.
