24th EUSPEN International Conference & Exhibition

Our yearly presence at the EUSPEN International Conference is always filled with great insights into the current developments in precision engineering and nano-manufacturing technologies. This year, the conference was held in Dublin, Ireland, where our esteemed delegates, Dr Zhang Jiong (currently Assistant Professor at City University of Hong Kong) and Mr Guo Yunfa (our penultimate year PhD candidate), were warmly welcomed by the University College of Dublin that hosted the prestigious conference.

Dr Zhang Jiong gave an oral presentation in Session 1: Digital Manufacturing and Automation in Precision Engineering on the topic titled Non-destructive measurement method for internal surface roughness based on a magnetic tool and machine learning model.

Surface quality evaluation of internal surfaces is vital while challenging. In this paper, we proposed a novel and non-destructive method for internal surface roughness measurement based on a magnetic tool and a data-driven model named fuzzy broad learning system (FBLS). The magnetic tool is placed on the workpiece’s inner surface and dragged by an external magnet. The force between the tool and the workpiece is recorded and used as input for the FBLS. FBLS combines the logical reasoning ability of a fuzzy system with the self-learning ability of a neural network. It is suitable for nonlinear and uncertainty modelling, and the computational efficiency is high. Experiments show that this method is suitable for workpieces with surface roughness (Ra) larger than 1 μm and its average measurement error is only 10.1%, which is adequate for the quality control of most engineering surfaces. This method may be further applied to surface quality evaluation of additively manufactured internal surfaces and complex channels.

Mr Guo Yunfa gave a poster presentation in Session 4: Mechanical Manufacturing Processes on the topic titled Effect of electric fields on micro-scratching of calcium fluoride.

Electric field assistance has shown positive effectiveness in facilitating the machining of conductive materials (e.g., metals and alloys). However, the electric field effect on the manufacturing performance of non-conductive materials is less studied. In this study, an external electric field is employed in micro-scratching of a non-conductive ceramic material, single-crystal calcium fluoride (CaF2). The electric field effect on the machinability of non-conductive CaF2 was assessed by characterizing scratched surface morphology, critical load, scratch profile, and acoustic emission (AE) signals. Compared to conventional scratching, the scratched surface quality was improved with fewer cracks and surface defects after applying the electric field. The critical load that quantitatively identifies the position of ductile-brittle transition and crack formation was larger with the electric field. A smoother cross-sectional scratch profile and larger residual depth were observed with the assistance of an electric field. The lower AE amplitude with the electric field further suggests that the application of the electric field can effectively suppress brittle material removal of single-crystal CaF2 in micro-scratching. The mechanism responsible for enhanced machinability of CaF2 in the presence of an electric field was discussed based on the theory of electro-plasticity and further revealed by molecular dynamics simulations. This study deepens the comprehension of electric field-assisted machining technology in non-conductive materials and opens a novel path for improving the manufacturing efficiency of ceramic components.

Yunfa awarded the Heidenhain Scholarship

We express our congratulations to Mr Guo Yunfa for being one of the ten outstanding candidates to have received the prestigious Heidenhain Scholarship, which is exclusively awarded to Masters/PhD student researchers who have displayed significant potential in the field. The scholarship earns candidates travel bursaries and complimentary euspen conference registration fees.