The influence of self-lubricating coating during incremental sheet forming of TA1 sheet

Incremental sheet forming (ISF) is an advanced sheet forming process featured with great flexibility, enhanced formability, and high efficiency especially for small batch production. However, the poor surface finish and the large forming load are the main shortages of ISF, especially for the difficult-to-form materials such as titanium sheets. In the present work, a self-lubricating coating was successfully prepared on pure titanium substrates by the atmospheric plasma spraying (APS) process before the forming process for improving the lubrication condition. It was found that the friction is significantly reduced during the forming process when using the self-lubricating coating compared with that with traditional mineral oil as the lubricant. In addition, the wear rate suggests that components' surface has self-lubrication coating after forming due to excellent wear resistance of the coating. Furthermore, a better external surface quality can be obtained when the friction resistance is lower since the friction plays a crucial role in material deformation. The tensile test suggests that the effect of heating on sheet mechanical properties is opposite to coating on that. Finally, the effects of coating on mechanical properties of the TA1 sheet were investigated and the appropriate parameters for spraying the self-lubricating coating were determined. The present work provides a novel method for enhancing the product quality in ISF through lubrication condition improvement.