Laser Structuring

 

Process Steps

Laser Structuring (2.5D machining) starts with a CAD model.  The model is converted to its negative form which represents the material to be removed by the laser.  Intricate geometries can be machined as long as the features are ‘top-down’.

positivenegative1

The negative form of the CAD model is sliced along the Z-axis at even intervals.  Each slice represents the amount of material removed by each pass of the laser.  Raster lines are automatically generated for each slice with spacing determined by the laser spot size and desired results.  Each line represents a scan path of the laser.

raster

The part is aligned in the machine through vision and laser measurement systems and the laser machining operation is performed.  Process parameters such as pulse repetition rate, focal distance, laser scan speed, and pulse duration are carefully controlled based on the material and desired results.  Different process parameters may have different tradeoffs.  For example, it may be possible to drastically increase the material removal rate at the expense of resolution and surface finish.  Intricate features can be created with fine detail.

 

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A 5x3mm test form machined into a flat piece of graphite (top) and  tungsten carbide (bottom).

Applications

Laser structuring is often used in conjunction with conventional machining operations.  Some examples of laser structuring applications combined with conventional techniques include:

  • Applying a radius or chamfer to small holes, slits, or otherwise small intricate geometries especially in hard, difficult to machine materials
  • Precision de-burring of small or delicate geometries
  • Applying a controlled surface texture such as in mold cavities or for other cosmetic or functional reason
  • Selectively removing material in difficult to machine areas or on parts difficult to fixture or hold
  • Selectively removing a coating on intricate geometry
  • Creating chip breaking geometry and rake angles on end mill inserts
  • Micro-Machining features on electrodes used for sinker EDM processes

Materials

Laser machining performance for different materials is highly dependent on the wavelength of the laser and other process parameters such as laser pulse duration.  Some materials may also require secondary operations to remove debris generated during the machining process.  Example materials with excellent machining properties include:

  • Aluminum
  • Steel
  • Tungsten Carbide
  • Zerconia Ceramic
  • Alumina Ceramic
  • Silicone Carbide Ceramic
  • Graphite

Other material can be evaluated on request.

 Capability

Laser structuring is a very capable and cost effective process for creating small features on traditionally difficult to machine materials.  Typical capability includes:

  • Flatness of machined surface to <5um
  • Surface finishes below 1um RA
  • Depth of surfaces accurately held to <5um
  • Spatial feature resolutions <25um
  • Draft angles <15 degrees on ‘vertical’ walls

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A 5x5mm test form machined into a flat piece of tungsten carbide and YTZP (Zeroconia Ceramic)

Trade-offs

Laser structuring is not a replacement for conventional machining and is best used in conjunction with other techniques.  Several process tradeoffs include:

  • Relatively low material removal rate
  • Inability to create vertical walls
  • Secondary operations needed to clean some materials