Laser marking and engraving of aluminum oxide surfaces.

Laser engraving is one of the most modern ways of marking metal parts, which is used in many areas to mark manufactured parts for easier identification. Most of the company's customers request the marking of their ordered parts, which usually only need to be provided with an article number/drawing number, barcode and/or QR code, or possibly the manufacturer's company logo. The purpose of the procedure is to ensure that the product can be identified months or years after production/installation in the event of a possible quality complaint, as to who manufactured it and when. In many cases, the product is delivered to the Customer's warehouse after production, and its installation is only carried out later, where dimensional deviations and other errors may also occur.

In addition to product marking, other engraving tasks are also typical, e.g. engraving vernier scales on flat and cylindrical surfaces, graphic marking of decorative objects, removal of corrosion from steel surfaces, etc.

The quality of laser marking can be controlled by fine-tuning several parameters. The primary consideration is the quality of the material to be engraved, different settings are used for steel, aluminum, anodized aluminum, other non-ferrous metals, plastics, glass, etc. in case.

The parameters to be set:

• Frequency
• Pulse width
• Speed
• Power
• Hatch delay

The company conducted the research on a TowerMark LX type industrial, high-performance, extremely versatile and configurable laser engraving machine.
The equipment can be equipped with different types of laser sources (CO2, FIBER, FLYAIR, FLYAIR GREEN, GREEN FIBER, UV), in this case a fiber laser was used.

It provides a large working space considering the actual area occupied by the machine, and yet it works as a stand-alone unit, offering the possibility of installing different accessories inside the unit according to specific needs.

The The working surface measures 950 mm x 530 mm and is made of heat-treated, anodized, scratch-resistant aluminum. The surface is perforated for easier positioning of workpieces and faster pre-marking.

The main feature of the TowerMark LX is that it offers an innovative system where the laser moves along the X and Z axes, allowing the marking of individual workpieces of different sizes and, more importantly, the use of pallets up to 600 mm x 170 mm long. The system does all this in a way that does not obstruct the working area of ​​the marking machine at all and utilizes all available space.

The X and Z axes can be fully controlled with the FlyCAD marking software. The motors with built-in encoders can also be controlled using a joystick, which allows instant focusing thanks to SmartFocus technology. The operator can quickly find the right position for perfect marking, both on flat surfaces and especially on surfaces with complex geometry. The door with a large viewing window providing an excellent view of the marking area can be operated pneumatically.
The work area also has a rotary axis for marking cylindrical workpieces.

The main parameters of the machine:

• visible laser guide light for positioning and simulating the engraving operation
• intelligent autofocus
• 250 mm electric table lift
• front and side material loading (even for fiber materials of several meters)
• LaserStyle graphical user program in Hungarian
• exhaust device
• cylinder rotator
• Fiber laser 1.064 nm
• Power 30 W

Thanks to the wide range of adjustable parameters of the fiber laser, it is possible to mark and engrave any metal (shown in the pictures below: brass, steel, aluminum), and within certain limits, glass and some types of plastics can also be marked.

The process of laser engraving

The first step in laser engraving is to position the workpiece in the machine's workspace.

After this, a new project is started and the logo, text, etc. that you want to engrave are created within the working area (yellow square):

A pre-saved parameter must be associated with the text or logo. The values ​​recorded in the parameters can be adjusted for each material by trial engravings, modifying different values ​​(speed, power, frequency, pulse width, delay).

Within the framework of the project, the applicable parameters were determined experimentally for different materials, which are as follows:

After this, the head position is adjusted in the X and Z directions. (The head cannot move in the Y direction).

By projecting the set position onto the piece, the position and size of the area to be marked can be checked, which is marked by the machine with a bounding rectangle.

If the placement is correct, engraving can begin:

In the case of a sequence of numbers, the process is complete in a few seconds (3-6 s).

Within the framework of our R&D project, the cutting technologies of typical automotive component materials and component groups that fit into the production profile of Török Gépipari Kft. were defined and developed. The machining and surface treatment (anodic oxidation - anodizing) parameters of the most common materials, such as the optimal cutting parameters, machining type technologies, surface treatment, preparation methods and processes, were examined. The wear resistance of hard anodized surfaces was examined according to existing methodologies. Finally, the post-treatment options of typical raw materials and their aluminum oxide surfaces were determined in terms of laser marking and engraving. The company has also incorporated all of this into its daily production profile, so the results of the development can be immediately applied in the daily routine. At the same time, the theoretical and physical results of this dissertation can also be freely utilized by companies dealing directly or indirectly with machining and surface treatment (e.g. engineering offices, product designers, etc.).