High-power picosecond laser drilling/machining of carbon fibre-reinforced polymer (CFRP) composites

A Salama,A Sabli,P Mativenga,L Li

doi:10.1007/s00339-016-9607-8

Abstract

The large differences in physical and thermal properties of the carbon fibre-reinforced polymer (CFRP) composite constituents make laser machining of this material challenging. An extended heat-affected zone (HAZ) often occurs. The availability of ultrashort laser pulse sources such as picosecond lasers makes it possible to improve the laser machining quality of these materials. This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system. Small HAZs (<25 µm) were obtained on the entry side of 6-mm-diameter hole drilled on sample of 6 mm thickness, whereas no HAZ was seen below the top surface on the cut surfaces. Multiple ring material removal strategy was used. Furthermore, the effect of laser processing parameters such as laser power, scanning speed and repetition rate on HAZ sizes and ablation depth was investigated.

Highlights

The increasing use of carbon fibre-reinforced polymer (CFRP) composites, because of their unique properties, in a wide range of applications including aerospace, automotive and sport equipment [1,2,3] has necessitated the development of effective and lowcost machining processes to process these materials with high quality and efficiency
This paper reports an investigation on the drilling and machining of CFRP composites using a state-of-the-art 400 W picosecond laser system
Since the heat-affected zone (HAZ) is influenced by the laser–material interaction time, the release of high pulse energy in a very short time, as in the case of ultrashort pulsed laser sources such as picosecond and femtosecond lasers, the laser beam directly evaporates the materials and leaves little time for the heat to propagate to the adjacent substrate, limiting the HAZ extension [11]

Summary

Introduction

The increasing use of CFRP composites, because of their unique properties, in a wide range of applications including aerospace, automotive and sport equipment [1,2,3] has necessitated the development of effective and lowcost machining processes to process these materials with high quality and efficiency. Machining of CFRP composites differs considerably from machining conventional metals due to their inhomogeneity properties, heat sensitivity and the carbon fibre being very abrasive [4]. CFRP composites exhibit various forms of damages during mechanical machining and water jet machining. Such defects include carbon fibre pull-out, delamination, excessive tool wear, abrasive penetration, acoustic noise and abrasive slurry disposal [5,6,7]. The large differences in physical and thermal properties of the CFRP constituents make laser machining challenging. Laser processing of these materials often leads to an extended HAZ, which is considered as the major obstacle for its wide industrial applications. Since the HAZ is influenced by the laser–material interaction time, the release of high pulse energy in a very short time, as in the case of ultrashort pulsed laser sources such as picosecond and femtosecond lasers, the laser beam directly evaporates the materials and leaves little time for the heat to propagate to the adjacent substrate, limiting the HAZ extension [11]

Methods

Results

Discussion

Conclusion