laser etching on stainless steel

There are many articles in the industry that provide information on the steps to use laser engraving on stainless steel. The truth is, you can’t just use any laser engraving machine to engrave stainless steel. Here’s why this metal alloy is different.

Laser engraving on stainless steel leads to corrosion

Engraving metal such as stainless steel, with a laser system, can cause the removal of a significant protective layer. In fact, any method that laser marks the surface (deep or shallow) will remove this protective layer from the metal.

This thin protective layer is made up of chromium oxide. Chromium oxide forms naturally when chromium reacts with oxygen. This process is a desired form of oxidation known as passivation. The resulting layer prevents corrosion by preventing oxygen from reaching the underlying steel.

When that layer is removed, oxygen causes a chemical reaction in the bare steel. That reaction is known as oxidation. The result is rust, which creates weak spots that gradually destroy the material. That’s what happens when laser marking stainless steel by inscription or laser engraving.

For stainless steel, laser annealing should be preferred and not laser engraving. 

To create markings such as logos, logo engraving, serial number or data matrix codes on stainless steel, you must rely on laser technology that does not remove the chromium oxide layer from the surface.

For such a need, only one technology leaves a permanent mark directly on stainless steel. This technology is laser annealing.

Compared to the CO2 laser, the fiber laser allows for annealing that chemically modifies the steel located under the chromium oxide layer. To do this, the surface is heated until it temporarily melts. During this short period of time (milliseconds), the oxygen travels below the surface. This creates a desired and controlled form of oxidation below the surface.

stainless steel laser engraving

  • BLACK MARKING

The black marking process heats the material locally to just below its melting point. This generates oxide layers on the workpiece surface that are associated with metallic annealing colors. It is also the preferred method when a precision fit is required or there is a need to avoid material bulging. It can only anneal metals that change color when under the influence of heat and oxygen, i.e. steels and titanium, but not aluminum or non-ferrous metals. The oxide layer is usually black, but it can also have other annealing colors.

Black marking is a marking process that produces very high contrast dark marks. This structured surface reduces the amount of light that is reflected, and the result is a deep, matte blackening of the mark, which appears the same when viewed from any angle. This makes marking non-abrasive.

  • Heat treatment process.
  • Aesthetic and high contrast marking.
  • Accumulation of a layer of oxide that darkens.
  • Low speed process.
  • Works only on stainless steel/other alloys.
  • High level of detail.
  • No cracks or bumps.
  • Possibility of obtaining a wide range of colors with optimized laser parameters.
  • Relatively slow dial times.

Micropercussion & Scratch Technology

MICROPERCUSSION :

The principle of the dot peen marking machine is based on creating depressions in the material using a vibrating tool. This creates a series of dots that form a high-quality, legible, permanent, direct mark on the workpiece. With dot peen marking technology, you don’t have to worry about adapting to the material, the marking results are consistent regardless of the type of steel or its hardness. Dot Peen technology offers a high quality, legible and permanent marking to resist erasing, fading, corrosion and all kinds of treatments. Dot peen marking is one of the most versatile technologies because it is possible to mark very fine marks, but also to make deep marks according to your needs. What’s more, this technology does not heat the material and does not create any breaking point in the material, whatever its thickness. Initial cost and operating cost are lower with this technology. Percussion technology enables stainless steel parts that are generally subject to high stress (specifically in the automotive and aviation industries) to have high temperature and heat resistant markings.

  • Pneumatic Point Punching – Our point punch marking machine is best for marking applications that require a very short cycle time to meet the speed requirements of industrial sectors. The wide range of styli available allows fine, wide, superficial or deep marking and adapts to irregular surfaces thanks to the 3D stylus that allows marking on complex parts with irregular shapes.
     
  • Electromagnetic Drilling – Best suited for applications that need high accuracy and consistency. It is particularly effective for marking DataMatrix codes. Electromagnetic dot peen technology is a high precision marking solution to meet traceability and identification requirements. Thanks to its panel of electromagnetic probes, it is possible to carry out all kinds of fine or deep surface marking.

TRACING TECHNOLOGY :

The scribing machine uses a carbide or diamond tip to apply a permanent mark directly to stainless steel (up to 62HRC). Unlike micropercussion, the tip does not vibrate, but glides across the surface; marking and drawing a continuous homogeneous line. The result is very clear and aesthetic. This process has the advantage of being very quiet, which is why it is particularly used to mark hollow parts with high resonance, tubes, sheets and to engrave identification plates, for example. Tracing marking technology offers the best marking depth/speed ratio and high quality marking to meet identification and traceability needs

Cnc Engraving Technology

The material is removed by cutting tools, “engraving cutters” of various sizes and shapes. Rotary machine engraving has very good adaptability to any type of stainless steel, even painted, and the possibilities are consequent, even the smallest and finest characters and logos can be engraved to create a durable and artistic engraving. This technology also brings out the shine of the stainless steel and the appearance of the engraving appears natural.

In addition, the constant and strong engraving depth guarantees a sustainable result and allows you to apply lacquer or paint afterwards to add color to your creation. It is very popular in the jewelry, machine shop and name tag industries. The hardness of stainless steel requires a collet shaft (including a high-frequency shaft) to hold the cutting tool firmly.

Tools for processing stainless steel have a specific sharpening: Percut range for drilling, Twincut range for engraving. When milling stainless steel, a lubricant system and a product adapted to stainless steel (part of the Gravotech range) is necessary to evacuate chips and increase the life of the cutting tool.