Feasibility study of a new approach to removal of paint coatings in remanufacturing

Environmental issues are recognised as being increasingly important, especially in the 21st century; researchers have thus proposed remanufacturing as a means of improving manufacturing sustainability. Cleaning the end-of-life products, that saves commercial values, is one of the most demanding steps and is usually one of the most polluting stages. Product surface coatings, are especially difficult to remove, in this process, because they have been designed to be robust during the service. Traditional methods, aqueous cleaning for instance, are either water consuming or use large amounts of chemical cleaning agents, which are obviously environmentally unfriendly. In this paper, a new approach to removing the paint layers on the surface of the retired product is proposed. The cleaning uses supercritical carbon dioxide (SCCO₂) as the pre-treatment, and then wet shot blasting cleaning removes the residues on the treated surfaces. It is difficult to get paint layers in the same condition and the real products are too big for the experimental platform. Experiments were thus carried out using metallic paint sprayed on the steel, with uniform dimensions, mimicking the real paint coatings on the products. The mechanism of SCCO₂ treatment was first analysed and specimens treated in different conditions were illustrated. Single-particle shot experiments were afterwards carried out to determine the proper cleaning parameter. The eventual cleaning results using wet shot blasting demonstrated that theoretical analysis was appropriate in this SCCO₂ treatment. The resultant cleaning, by use of these two methods, showed satisfactory removal results.