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 Al2O3 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.

► Hole circumference is free from large size thermal and mechanical defects.
► Formation of Al2O3 and AlO at kerf surface is evident.
► Locally scattered some small dross attachments are observed at hole exit.
► Thermal stress is almost three times higher for 2 mm diameter hole as compared to 8 mm diameter.
► von Mises stress attains high values in the mid-thickness region of the workpiece.