Laser hole cutting in aluminum foam: Influence of hole diameter on thermal stress

Laser cutting of aluminum foams avoids structural damages, which can be observed during mechanical cutting process. High thermal stresses can be formed in the laser cut sections due to high temperature gradients while limiting the practical applications of parts. In the present study, laser cutting of 2 mm and 8 mm diameter holes into aluminum foam is carried out. Geometrical changes in the cut section are examined using optical and scanning electron microscopes and oxide compounds formed at the kerf surface are identified by X-ray diffraction. Temperature and stress fields are predicted numerically in the cut section in the line with the experimental conditions. It is found that defect free cutting of small diameter holes is possible in 8 mm thick aluminum foam. Air trapped in the pores prior to laser cutting undergoes oxidation reactions with molten material while resulting in forming of Al ₂O ₃ and AlO compounds at the cut surfaces. von Mises stress predicted for 2 mm diameter hole is almost 3 times higher than that corresponding to 8 m diameter hole.