Review on mechanism and process of surface polishing using lasers

Abstract

Laser polishing is a technology of smoothening the surface of various materials with highly intense laser beams. When these beams impact on the material surface to be polished, the surface starts to be melted due to the high temperature. The melted material is then relocated from the ‘peaks to valleys’ under the multidirectional action of surface tension. By varying the process parameters such as beam intensity, energy density, spot diameter, and feed rate, different rates of surface roughness can be achieved. High precision polishing of surfaces can be done using laser process. Currently, laser polishing has extended its applications from photonics to molds as well as bio-medical sectors. Conventional polishing techniques have many drawbacks such as less capability of polishing freeform surfaces, environmental pollution, long processing time, and health hazards for the operators. Laser polishing on the other hand eliminates all the mentioned drawbacks and comes as a promising technology that can be relied for smoothening of initial topography of the surfaces irrespective of the complexity of the surface. Majority of the researchers performed laser polishing on materials such as steel, titanium, and its alloys because of its low cost and reliability. This article gives a detailed overview of the laser polishing mechanism by explaining various process parameters briefly to get a better understanding about the entire polishing process. The advantages and applications are also explained clearly to have a good knowledge about the importance of laser polishing in the future.

Laser polishing of additive manufactured Ti6Al4V alloy: a review

“…During this period, the molten metal evaporates less, so there is almost no material loss in the laser polishing process. [39][40][41] The diagram of laser polishing is shown in Fig. 1.…”

Influence of Overlap on Surface Quality in the Laser Polishing of 3D Printed Inconel 718 under the Effect of Air and Argon

“…For most metal CW-LP applications, Nd:YAG and fiber lasers are used due to their range of available power, initial and exploitation costs, and versatility. They generate a beam that is characterized by a satisfactory absorption for most metals [ 9 , 11 , 12 ].…”

“…The distance between neighboring tracks is kept constant and it is called the hatching pitch ( h ). When its value is less than the diameter of the laser beam ( D ), the overlap ( OL ) can be calculated while using Equation (1) [ 12 ]. …”

“…Because the energy density of the laser beam is not uniformly distributed on the surface, the overlap is needed in the case of LP based on re-melting [ 12 ]. However, the zigzag strategy is related to heat accumulation in the turning points, in turn causing the curb effect [ 16 ].…”

Theoretical and Experimental Study of Ultrasonic Vibration-Assisted Laser Polishing 304 Stainless Steel

“…Because of the high temperature of the laser beam, a molten pool is formed on the thin layer of the workpiece surface. Under the action of multi-direction forces such as gravity and surface tension, the molten material is relocated from peaks to valleys and re-solidified again [18]. Ramos and Bourell [19] proposed that laser polishing metal materials should be divided into two processes: shallow surface melting (SSM) and surface over melt (SOM).…”