Surface Texturing with Laser Ablation

Much of a product’s appeal to the consumer has to do with its look and feel—literally, the texture of its visible surface. The pattern of tooled leather, the weave of a rich fabric or the grain of weathered wood pleases the eye and gratifies the touch. Reproducing such textures on metal workpieces is one of the primary applications for a line of laser-powered machine tools from GF AgieCharmilles (Lincolnshire, Illinois). The three- and five-axis models in this line use a high-powered laser beam that impinges on the workpiece surface under high speed computer control to remove material by ablation, thus creating virtually any surface texture that can be digitized. Ablation can be described as a method to melt and vaporize a workpiece material with high heat.

In addition to texturing, this process can be used to engrave, mark, label or render a microstructure on a surface in 2 or 3D. According to the company, this process can be applied to aluminum, copper, steel, graphite, carbide, brass, ceramics and other materials. Laser ablation is said to be more flexible, predictable and environmentally benign than acid etching or other conventional surface treatment.

The line consists of four models, the Laser 500, 600, 1000 and 1200. All share the same workpiece capacity (a 700-mm cube) and machining travel (1,200 by 900 by 1,200 mm in X, Y and Z), but they differ in the configuration of the laser head. The Laser 500 has a three-axis head for 2D or 2½D work and can be considered an entry-level model. In contrast, the Laser 1200 is a high-end model with a five-axis head for full 3D work. A pulsed, 20-watt fiber-optic laser is standard, but 50- and 100-watt lasers are optional.

Lenses with different focal lengths can be exchanged quickly to produce the desired spot size on the workpiece surface. Intricate designs at a shallower depth require a more finely focused laser spot, whereas heavier patterns can be produced more quickly with a wider focus. The choice of lenses provides this flexibility.

Other features common to all models include a camera for fine positioning, a 3D touch probe for laser positioning, an exhaust nozzle for vapor removal and an air gun to clear the laser contact zone. The machines can be integrated into an existing automated system or equipped with an add-on carousel pallet changer (with System 3R or Erowa pallets).

Although process efficiencies are part of the company’s main message about the series, which will be introduced to the U.S. market at IMTS 2010, GF AgieCharmilles is also focusing on the creative, imaginative possibilities that this technology opens up to product designers, mold makers and engineering studios. For example, the virtual texture to be formed on the workpiece surface can be created in 2D graphic software such as AdobePhotoshop or generated by a 3D scanner in a reverse engineering process.

This means an element of artistry can be infused into the design and manufacturing process that enables innovative users to differentiate themselves in the marketplace. The texture or pattern produced by the laser can be easily modified or varied, so an element of customization can also be introduced into the production process.

Interestingly, laser ablation supplements and complements other manufacturing processes in the company’s portfolio, such as wire EDM, die sinker EDM and high speed milling. For example, an otherwise finished plastic injection mold can be textured directly, or an electrode can be textured to modify the mold surface with the EDM process.