Grinding of Thermal Spray Coated Aircraft Engine Parts

Abstract

Aircraft engines that must be certified separately from the platform should comply airworthiness and remain unchanged for all types of operations and in all environments. Together with this, they might only be preferred by airlines if they are competitive in terms of several aspects such as fuel efficiency, speed, and maintainability. These requirements are met by an interdisciplinary effort including engine design, component materials, manufacturing techniques and electronic control. An illustrative example to this is the critical components designed and manufactured of titanium or superalloys and coated afterwards to resist various wear causes and to facilitate easy, cost-effective maintenance by keeping the component itself only via renewing the coating after certain flight hours. Although this solution sounds reasonable and feasible, it needs a considerable know-how level to apply a proper coating and subsequently to size it to an acceptable level of dimensional quality and surface integrity. In order to meet researchers' and engineers' know-how needs on the subject, this paper presents a systematic review on grinding of thermal spray coated aircraft engine parts. In this paper, spray coatings, which offer the widest substrate material range are explained in detail regarding their materials, application methods and characterizations. Later on, grinding of these is narrated considering tools and process parameters such as cutting speed, feed, and depth of cut. Finally, the influence of grinding conditions on dimensions, surface quality, hardness, residual stresses, and microstructure is discussed. The paper is concluded with a state-of-the-art summary and emphasis on research gaps and future perspectives on the subject.