Determining Laser Cutting and Drilling Parameters for Glass Fiber Reinforced Polymer Composite Materials

Summary

Glass fibre is manufactured from materials such as silica, colemanite, aluminium oxide and soda. These raw materials are melted at high temperature in glass furnaces and glass fibre is produced by forcing the mixture through small openings at the micron level under pressure. Glass fibre is the most commonly used fibre type in the production of fibre-reinforced polymeric composites. Its strength is very high. Its thermal resistance is quite low. They are resistant to chemical materials. They have no moisture absorption properties. They have no electrical conductivity. Glass fibre-reinforced polymeric composite materials are obtained by joint moulding of the reinforcing material and the resin (matrix) used as a carrier. This moulding process is carried out in many different ways. What is important in this moulding process is the proper wetting of the glass fibre with the matrix. In this moulding process, the matrix performs the task of transferring force to the fibre and ensuring uniform distribution, protecting the fibres from environmental effects and impacts, increasing the toughness of the composite material and preventing cracks, fractures etc. in the materials. Glass fibre-reinforced polymeric composite material has high strength and is very lightweight, so it is used in many sectors such as aviation, space technology, automotive, food, construction, entertainment, technology and others. In the production of glass fibre-reinforced polymeric composites, after the moulding process, the removal of excess material, the levelling of the part as required by the production process, is carried out mechanically. This creates high costs, time loss and increases error rates. In this study, cutting and drilling operations were performed using laser. Optimum laser parameters and cutting speeds were determined. Cutting and drilling operations were successfully carried out on 5 mm thick glass fibre-reinforced polymeric composite plates in different colours using Nd:YAG lasers at different pulse widths and wavelengths, and optimum laser parameters were determined.

Introduction

Glass fibre is manufactured from materials such as silica (SiO2), colemanite, aluminium oxide (Al2O3) and soda (NaHCO3). These raw materials are melted at high temperature in glass furnaces and glass fibre is produced by forcing the mixture through small openings at the micron level under pressure. Glass fibre is the most commonly used fibre type in the production of fibre-reinforced polymeric composite (FRP) materials. Their thermal resistance is quite low, and they are quite resistant to chemical materials. They have no moisture absorption properties and no electrical conductivity. Glass fibre-reinforced polymeric composite (FRP) materials have high strength and are very lightweight, so they have become a popular industrial material in use in different fields today. While this material was initially used in the space and aircraft industry, its importance has increased as it has begun to be used in many different sectors such as automotive, food, construction, entertainment and technology. This use brings quite different requirements to the forefront on the material. Glass fibre-reinforced polymeric composite (FRP) materials are obtained by joint moulding of the reinforcing material and the resin (matrix) used as a carrier. This moulding process is carried out in many different ways. [1] Resin Transfer Moulding (RTM) Production Method: The material we used as test specimens is aquapark slide material produced using the RTM method. With products manufactured using gel coat, it is possible to produce FRP material with both surfaces having the same gloss, smooth and complex structures. The mechanical properties of 5 mm thick FRP material produced by RTM method are given in Table 1. Precise cutting and drilling of polymeric composite materials at the micron level is particularly important for medical applications[2,3]. In the literature, studies on laser micro-machining of polymers have increased recently[2-5]. The underlying reason for this is the production of micro-lenses from polymers and the formation of tissue-polymer-based membrane structures for medical applications. This is because the interaction between tissue and the pattern and pore structure to be created differs [2]. In this study, cutting and drilling operations were performed on 5 mm thick glass fibre-reinforced composite materials using lasers of different wavelengths, and optimum laser parameters were determined.

2. Method

Figure 1 shows schematically the production of glass fibre [1]. Table 1 shows the mechanical properties of the glass fibre-reinforced plastic composite (FRP) material used as test specimens. The experimental arrangements given in Figure 2 were used to perform cutting and drilling operations on the materials. Cutting operations were performed primarily on millisecond (ms) pulsed laser, while drilling operations were carried out on nanosecond (ns) pulsed laser. The laser parameters used are given in Table 2. Argon (Ar) was used as a protective gas in all cutting and drilling operations. Figure 3. Experimental arrangement. (A) shows the experimental arrangement used for drilling operations with ns-pulsed Nd:YAG laser, (B) shows the experimental arrangement set up for cutting and drilling operations with ms-pulsed Nd:YAG laser.

All of the prepared arrangements consist of systems with precise and controlled movements. Microscopic images were obtained from an Olympus microscope.3. Discussion 3.1. Drilling with Laser

Drilling operations were performed on glass fibre-reinforced composite material using ms and ns pulse width lasers available at the Laser Technologies Research and Application Centre (LATARUM) at Kocaeli University. The laser parameters used are given in detail in Table 2 (for ns laser). Similarly, microscopic images of the drilling operations performed are shown in Figure 4 and Figure 5 for different lasers.   As can be seen from Figure 2 and Figure 3, using ns pulse-duration laser, drilling operations can be performed on the material without combustion occurring. As laser power increases, there is approximately no change in hole diameter, but the diameter of the HAZ (heat-affected zone) formed in the gel coat portion increases. This is shown more clearly in Figure 6. In drilling operations performed with ms pulse-duration laser, combustion occurred. The reason for this is the magnitude of energy transfer resulting from the long pulse duration. Toxic gas emissions occur in laser operations on polymers. For this reason, such operations should be performed in ventilated environments. Additionally, since many polymers burn easily, operations should be conducted with low pulse-duration lasers. Figure 6 shows cross-sectional images of specimens where drilling operations were performed at different laser powers using ns-pulse-duration laser. As can be seen from the figure, the diameter of the crater formed in the gel coat area increases with increasing energy. The diameter of the hole formed inside the composite decreases as it goes deeper into the material. Uniform holes approximately 200 μm in diameter were formed inside the material.

3.2. Cutting with Laser

Figure 7 shows the cutting operation performed using ms-pulse-duration laser. Table 3 specifies the laser parameters used in the cutting operation. As can be seen from Figure 7, a smooth cut with sharp edges approximately 2 mm in depth was successfully achieved.4. Results

In this study, cutting and drilling operations were successfully performed on 5 mm thick glass fibre-reinforced composite materials using lasers of different wavelengths, and optimum laser parameters were determined. The results obtained are listed below. 1. On both lasers, holes approximately 500 μm in diameter were successfully created on the coloured gel coat layer of the composite material. In drilling operations performed using ms-pulse-duration laser, combustion of the gel coat portion was observed. 2. ns-pulse-duration lasers are more suitable for micro-level drilling operations to be performed on glass fibre-reinforced composite materials. Uniform channels approximately 200 μm in diameter were successfully created inside the composite material. 3. ms-pulse-duration lasers are more suitable for laser cutting operations to be performed on polymers. Mehtap Türkmen / Mechanical R&D / Polin Waterparks / FBE/Electro-Optical Systems Engineering / Kocaeli University Levent Candan / Senior Researcher / LATARUM Laser Technologies Research and Application Centre / Electro-Optical Systems Engineering / Kocaeli University Serçin Basut / Mechanical R&D / Polin Waterparks Ersin Kayahan / FBE / Electro-Optical Systems Engineering Department Chair / Kocaeli University / LATARUM (Laser Technologies Research and Application Centre) Deputy Director Ali Cansun / R&D Director / Polin Waterparks Acknowledgements We thank Polin Waterparks company (Kocaeli / Turkey) for their contributions.

References 1. Cam Elyaf Sanayi A.Ş. Bülten Sayı 6. 2. K.S. Tiaw, M.H. Hong, S.H. Teoh, Precision laser micro-processing of polymers, Journal of Alloys and Compounds, 449 (2008) 228–231. 3. M. R. H. Knowles, G. Rutterford, D. Karnakis andA. Ferguson, Micro-machining of metals, ceramics and polymers using nanosecond lasers, Int J. Adv. Manuf Technol. 33(2007)95–102. 4. V.N. Tokarev, J. Lopez, S. Lazare and F. Weisbuch, High-aspectratio microdrilling of polymers with UV laser ablation: experiment with analytical model, Appl. Phys. A 76(2003) 385–396. 5. N. Masmiati, P.K. Philip, Investigations on laser percussion drilling of some thermoplastic polymers, Journal of Materials Processing Technology 185(2007)198–203.