Influence of clearance and velocity during blanking on the fatigue behavior of cellulose-based biocomposites

Abstract

Cellulose-based biocomposites, such as Cottonid, are a promising class of materials to improve the carbon footprint of products during their service life. Cottonid has high technological potential due to its physical and mechanical similarities to engineering plastics and light metals. To replace traditional metallic materials in industry, cellulose-based semi-finished products need to be formed and cut. In particular, blanking is the most cost-effective and industrially common cutting method for metals. However, this study investigates the influence of various blanking process parameters on the quality and the fatigue strength of the resulting cutting edges of Cottonid. The presented results give insights on how the relationships between process parameters during cutting and resulting material properties known from conventional materials can be transferred to cellulose-based biocomposites like Cottonid. The relative clearance was varied between 4 and 10% and the cutting velocity between 0.05 and 10 m/s. It was evident that slower velocities and smaller clearances resulted in visibly better cutting edges. In order to relate this effect to the mechanical performance of Cottonid, new 3-point bend specimens were taken from the blanked strips for fatigue testing. It was found that the fatigue strength was significantly affected by the velocity and clearance. Further, similar to metallic materials, clean-cut (smooth area) and a fractured zone can be clearly distinguished. A good cutting edge quality results in a higher resistance of the Cottonid component against crack initiation at process-induced defects. The knowledge gained may enable an efficient cutting process for cellulose-based materials with higher fatigue strength in the future.