Qualify a NIR camera to detect thermal deviation during aluminum WAAM

Abstract

This paper proposes to qualify the minimal quality deviation that can be detected by a near-infrared camera during aluminum wire arc additive manufacturing. First, a review of the literature is done to highlight the interest in monitoring the melt pool in industrial condition for thermal management during manufacturing. It points out the relevance of the use of a near-infrared camera for steels, but it has to be demonstrated for aluminum alloys. Indeed, the melt pool of the aluminum is significantly dimmer and less distinct than the melt pool of the steels. An experimental design is proposed to qualify the minimal quality deviation that can be detected on a thin wall. The chosen default to correlate with the thermal deviation is the width of the wall. A method is proposed to extract a thermal metric from the camera image and to analyze its sensitivity to a width deviation of the wall. The paper shows the correlation between the width of the wall and the thermal metric for different heat conditions. Moreover, the thermal metric is sensitive to width deviation either on the wall scale or on the bead scale. It indicates the relevance of a near-infrared camera to detect heat accumulation-induced width deviation during wire arc additive manufacturing of aluminum alloy.