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Laser Ablation of Automotive Composite Panels for Adhesive Strength after Environmental Exposure

BLAIR E. CARLSON, SAUL S. LEE, CHRIS BASELA, BRUCE GREVE, GEORG HEIDELMANN, JEFF BATES

Abstract


Adhesive bonding of SMC composite materials traditionally requires scuff sanding pretreatment to achieve adhesive strength and fracture mode specifications. Scuff sanding is a manual operation that adds cost and generates undesirable dust. Pulsed laser ablation pretreatment was identified as an alternative method having the advantages of an automated, relatively low-cost surface pretreatment method. In contrast to conventional continuous lasers, modern pulsed infrared lasers (=1064 nm) have lower average power output but can deliver each shot within a very short period of time (~ 100-200 ns) resulting in high peak power output which can remove surface contaminants without the risk of heat damage. A feasibility study including environmental exposure was conducted to investigate the effectiveness of the laser ablation surface pretreatment for adhesive bonding of several SMC composites. Results show that with sufficient pulse laser energy, laser ablation pretreated substrates met the GMW 15921 specified average lap shear strength and failure mode requirements at room temperature and after water soak conditioning. Furthermore, laser ablated substrates exhibited comparable adhesive bonding performance compared to scuff sanded substrates. This suggests that laser ablation is a feasible alternative to sanding while offering the potential for automation and repeatability.

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