Study of correlation between scraps and main process parameters in flow-forming alloy wheels production

Flow-forming is a metalworking process that can be employed to produce lightweight, high-strength components by plastically deforming materials using circumferential and axial forces. This technique is employed in the automotive industry, particularly for wheel manufacturing, allowing a reduction of weight and an enhancement of the mechanical properties. The process has been extensively studied to investigate its influence on the final properties such as tensile strength, surface roughness, and fatigue resistance. However, challenges such as residual stress, defects, and micro-cracks remain crucial for optimizing final product quality. The study investigates the defects distribution after flow-forming of aluminium alloy (AlSi7Mg0.3) wheels. The process involves heating pre-formed wheels to a target temperature higher than 400 degrees C, followed by controlled plastic deformation using two rollers that reshape the material. Data on the process, such as spindle speed, material temperature, and machine downtimes, were collected from five flow-forming stations over a 23-week production period. Analysis of the data was conducted using the statistical methods ANOVA and DOE to correlate process variations with the occurrence of defects on products. Once the most impactful process parameters were identified, FEM methods were utilized to correlate the parameters with the temperature distribution in the parts and with the geometry achieved by the deformation. Furthermore, the numerical model of the process was utilized to investigate the effects of machine downtimes, defining a methodology to individuate and tackle the most relevant issues in flow-forming processes.