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Research Papers

# The Effect of Laser Beam Geometry on Cut Path Deviation in Diode Laser Chip-Free Cutting of Glass

[+] Author and Article Information
Salman Nisar1

Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M60 1QD, UK

M. A. Sheikh, Lin Li, Andrew J. Pinkerton

Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M60 1QD, UK

Shakeel Safdar

Department of Aerospace Engineering, College of Aeronautical Engineering, NUST, Risalpur 24090, Pakistan

1

Corresponding author.

J. Manuf. Sci. Eng 132(1), 011002 (Dec 23, 2009) (9 pages) doi:10.1115/1.4000695 History: Received April 20, 2009; Revised October 17, 2009; Published December 23, 2009; Online December 23, 2009

## Abstract

In laser cleaving of brittle materials using the controlled fracture technique, thermal stresses are used to induce a single crack and the material is separated along the cutting path by extending the crack. One of the problems in laser cutting of glass with the controlled fracture technique is the cut deviation at the leading and the trailing edges of the glass sheet. This work is about minimizing this deviation through an optimization process, which includes laser beam geometry. It has been established that the thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry. Experimental techniques are used to quantify cut deviation for soda-lime glass sheets under a set of conditions while finite element modeling is used to optimize the process and reduce (or eliminate) cut deviation. The experimental results of the effect of different laser beam geometries on cut path deviation have been presented in this study, along with the finite element modeling of the cutting process to simulate the transient effects of the moving beam and predict thermal fields and stress distribution. These predictions are compared with the experimental data. In comparison to other beam geometries, the triangular-forward beam at the leading edge and triangular-reverse and circular beam geometry at the trailing edge produces lower tensile stresses $(σxx)$ and hence minimizes the cut path deviation. The work also shows that beam divergence inside the glass plays a significant role in changing the cut path deviation at the bottom leading and trailing edges of the glass.

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## Figures

Figure 1

Schematic representation of the experimental setup (laser beam was delivered through an optical fiber cable)

Figure 2

Cut path deviation at (a) the leading edge and (b) the trailing edge

Figure 3

Cut path deviation for a rectangular-short beam at (a) top leading edge, (b) bottom leading edge, (c) top trailing edge, and (d) bottom trailing edge

Figure 4

Separation surface of the float glass using the controlled fracture technique

Figure 5

Average roughness Ra for different laser beam geometries

Figure 6

Illustration of the angular beam divergence inside the glass

Figure 7

(a) The coordinate system, (b) FE model with the constraints, and (c) cross-section view of the meshed domain

Figure 8

Illustration of angular divergence inside the glass

Figure 9

Illustration of angular divergence in the FE models: (a) circular and (b) triangular-forward beams

Figure 10

Experimental results of temperature versus time for different beam geometries at a point in the middle of the track defined by (x=25, y=25, z=0) measured using the thermal camera

Figure 11

Finite element modeling results of temperature versus time for different beam geometries at a point in the middle of the track defined by (x=25, y=25, z=0)

Figure 12

Temperature versus distance across the beam (FE model)

Figure 13

Temperature field across the depth (FE model)

Figure 14

Stress (σxx) versus time for different beam geometries at the top surface of 5 mm thick glass sheet at the leading edge

Figure 15

Stress (σxx) versus time for different beam geometries at the bottom surface of 5 mm thick glass sheet at the leading edge

Figure 16

Stress (σxx) versus time for different beam geometries at the top surface of 5 mm thick glass sheet at the center

Figure 17

Stress (σxx) versus time for different beam geometries at the bottom surface of 5 mm thick glass sheet at the center

Figure 18

Stress (σxx) versus time for different beam geometries at the top surface of 5 mm thick glass sheet at the trailing edge

Figure 19

Stress (σxx) versus time for different beam geometries at the bottom surface of 5 mm thick glass sheet at the trailing edge

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