Introduction:

Laser surface micro-texturing offers precise control of the size, shape and density of micro-surface texture features. In this technology, a pulsating laser beam creates micro-dimples or grooves on the surface of materials in a very controlled manner. The International Advanced Centre for Powder Metallurgy & New Materials (ARCI) has developed ultrafast laser surface texturing technology, which can improve the fuel efficiency of internal combustion engines.

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Laser surface micro-texturing:

• In this technology, a pulsating laser beam creates micro-dimples or grooves on the surface of materials in a very controlled manner.
• Such textures can trap wear debris when operating under dry sliding conditions and sometimes provide effects like enhancing oil supply (lubricant reservoir) which can lower friction coefficients and may enable reduced wear rate.
• The texture surfaces were created on automotive internal combustion engine components, piston rings and cylinder liners using 100 fs pulse duration laser.
• The micro dimples of 10-20 μm diameter and about 5-10 μm deep which have been created with laser beams had a regular pattern.

Properties / advantages of micro-texturing using ultrashort pulse lasers are:

• Machining of extremely small features of down to 10 µm or smaller
• Very high depth resolution (sub-micrometer)
• Works on nearly every material, including very hard materials
• Negligible heat effects: no melt, burrs, or other damage
• Contact and force-free process

Significance:

• The created textures were tested in an engine test rig under different speeds and temperatures of coolant and lubrication oil, and it was observed that there was a 16% reduction in the lube oil consumption with the use of texture on the piston rings.
• The 10-hour lube oil consumption test shows that the blow-by substantially reduced with textured rings.
• Fabrication of a pattern of micro dimples or grooves on the surface of materials results in a change in surface topography which generates additional hydrodynamic pressure, thereby increasing the load-carrying capacity of the surfaces.
• These textures can become useful for trapping wear debris when operating under dry sliding conditions and sometimes provide effects like enhancing oil supply (lubricant reservoir) which can lower friction coefficients and may enable reduced wear rate.

Application areas: There are various applications for the types of textures that can be produced using laser micro-texturing:

• Decorative textures – Improving the look of parts by adding high definition / low relief textures or LIPSS / color effects to parts
• Tribology – Changing frictional properties, e.g., reducing friction on moving parts (seals, bearings) or creating soft-touch consumer or medical parts
• Wetting – Making surfaces super-hydrophobic (water repellent) or super-hydrophilic
• Optical properties – Altering the surface to reduce glare, change the absorption of light, or even act as a diffraction grating (using LIPSS)