Machining of hybrid structures produced through cold spray technology: A preliminary study

Cold spray is a recently developed manufacturing technology for creating metallic layers on a variety of materials. Metallic particles are accelerated and strike the target surface using a pressurized gas flowing at supersonic speeds. In the last years, cold spray has gained increasing interest in different industrial scenarios, in particular, in the aerospace sector. Given the many fields of application, the need to understand how coated substrates behave when it is necessary to carry out machining operations arises. In this work, low-pressure cold spray equipment was employed to produce metal coatings on epoxy-based glass fibre-reinforced substrates optimized for cold spray deposition employing a layer of polypropylene on the composite surface. An automatic multi-purpose machine was used to drill 4mm diameter holes in the coated specimens considering the rotational speed fixed and varying the feed rate. The machined areas were then analyzed to assess the surface quality of the drilled holes and the burr morphology, considering different feed rate values and different entry surface of the drill-bit.