Vibration and casting surface finish

The authors have recently established that die vibration can be used to polish surfaces as they form during solidification [J. Man. Sci. Eng. 124 (2002) 435–443]. Evidence in the form of experiments performed on a purpose built rig has established that tangential vibration at certain frequencies and amplitudes influences surface finish. Micrographs combined with Talysurf readings show that die vibration can be used to generate surfaces with a quality significantly superior to that of the die. This is particularly important to the casting industry, as variable surface quality is common with existing casting technologies. The competitiveness of the casting process is affected by surface quality because secondary finishing operations are required, i.e. machining, polishing, plating, etc. This paper is concerned with an investigation into the feasibility of applying die vibration to commercial dies and processes. The feasibility of using piezoelectric translators in a casting environment is examined. Special design features are presented that serve to protect the translators from relatively high temperatures and lubricant contamination, whilst at the same time ensure good signal transmission. Boundary element models are presented that simulate the complex vibrational behaviour of arbitrary shaped dies. Numerical simulation is used to establish the conditions that prevail at the die surface. Although the research presented is at an early stage the numerical and experimental results provide evidence that this new technology is potentially applicability to commercial casting processes.