Laser Process

Laser Marking vs Laser Etching vs Laser Engraving

What is Laser Marking, Laser Etching, and Laser Engraving?

The above terms describe various methods of using a focused beam of light to permanently mark a given material. The process is typically carried out with a laser machine using an oscillator, a scanning mirror, and a focusing lens. Performance specifications for laser engraving and laser marking machines include wavelength, beam size, beam divergence, average power, operating current range, and operating temperature range. Beam size is the largest dimension of the beam while exiting the laser. Beam divergence is the change in beam diameter as a function of distance from the laser. For pulsed laser engraving and laser marking machines, specifications include pulse energy, pulse length and repletion rate. Pulse length is a measurement of time, not distance. Repetition rate is the number of pulses per second.

The type of material change observed when the laser interacts with the material can determine the difference between laser marking, laser engraving, and laser etching.

Laser Marking – a low temperature is generated at the material surface by the laser beam, changing the atomic structure of the material. The result is a change of the surface color that contrasts with the non-lasered material. This is considered an optochemical reaction.

Laser Engraving – a higher temperature is generated at the material surface by the laser beam causing holes in the material by evaporation of atoms where the laser beam touches the surface. The engraving depth depends on the laser power and engraving time. This is considered a thermal reaction.

Laser Etching – a milder process of laser engraving. The laser beam generates enough energy to modify the surface of the material to create a minimal depth mark with some texture.

The above terms describe the approach being used by the laser. The below terms describe in greater detail what is happening at the surface of the material.

Engraving: The laser beam penetrates the surface and removes material in the laser path through melting displacement and/or evaporation. As opposed to stamping, laser engraving produces no force on the rest of the piece and therefore no extra distortion.

Ablation: The laser beam removes a layer of coating such as black oxide, paint, anodization, chrome, etc., to reveal the base material or a second coating. This method creates very sharp and detailed characters and graphics due to the high contrast between the coating and the base material.

Color Change: The most common method for marking plastics such as polycarbonate and ABS. The laser beam produces a color change in the plastic material through carbonization or foaming.

Annealing: An excellent method for marking metals such as stainless steel and titanium, this process also relies on a color change to create characters and images. Annealing with the heat of the laser beam creates a dark, burr-free, permanent mark without noticeable surface penetration.