Innovative roughing approach for the footwear industry
One of the potentially critical footwear industrial processes is sole attachment where quality plays a significant role and seriously affects profitability. More specifically, poor and inconsistent surface preparation prior to sole attachment is responsible for wear failures. At the same time, the workforce is subject to health and safety risks related to leather dust found in the working environment as surface treatment is normally a manual process. Urged by these concerns, the IRIST project developed a novel process for surface treatment of leather and synthetic materials. This innovation is expected to improve the quality of surface preparation for both adhesive bonded and direct inject moulded constructions and consequently reduce warranty and scrap costs. Moreover, the IRIST results may contribute to a more efficient use of raw materials, while maintaining an eco-friendly and healthy working environment. Part of the project results involved a newly developed grit blasting technique for removing the upper layers of leather aimed for roughing purposes. Bond strength relies heavily on the resulting surface finish and the amount of leather removed. Special provision was given to the feasibility of the process to operate at those linear speeds that are required for roughing a complete shoe. With the aid of a simple linear test rig, experimental trials were conducted under variable conditions and parameters, such as differing blast angles, and grit speeds and densities. The viability of the technique was also tested for synthetic samples. All samples were examined in terms of the same order of bond strength with the aid of control sensors. The capabilities of the grit blasting method to remove the surface of the leather were demonstrated very effectively, showing that it can be employed for long-lasting shoe uppers. Moreover, the technique has the potential to be used in other sectors as well. Adoption of quality monitoring technology, developed by the project for application to any roughing system, could offer substantial cost reductions associated with quality monitoring when implementing automated systems.
