Danijela Rostohar

Low-pressure cold spray (LPCS) and medium-pressure cold spray (MPCS) provide field-deployable alternatives to stationary high-pressure cold spray (HPCS) for lightweight metallic component repair, although lower particle velocities and narrower process windows restrict the range of compatible repair materials. This review evaluates portable LPCS and MPCS repair as a distinct class of cold spray application using HPCS as the reference baseline. The article synthesises evidence on process windows, critical velocity, particle velocity ratio, deposition efficiency, deposit build-up capability, substrate preparation, porosity, oxide disruption, ceramic-assisted densification, interfacial bonding mechanisms, adhesion strength, hardness, residual stress, tensile behaviour, and fatigue performance. Attention is given to repair geometry, including blend-out depth, taper angle, aspect ratio, spray angle, and stand-off distance, because these factors govern particle impact conditions and interfacial integrity across practical repair geometries. Available evidence indicates that LPCS can achieve dimensional restoration, surface protection, and, in some cases, fatigue performance comparable with that of the substrate. However, structural qualification remains constrained by limited portable system fatigue data, few direct LPCS–MPCS comparisons under equivalent conditions, and inconsistent reporting of powder characteristics, surface preparation, porosity, and repair geometry. MPCS may extend the range of compatible repair materials while maintaining field deployability, but its peer-reviewed evidence base remains limited. Future work should prioritise controlled LPCS–MPCS comparisons, geometry-sensitive fatigue testing, standardised deposit quality metrics, and qualification procedures linking process window control with repair integrity.

With the rapid advancements in Information and Communication Technologies (ICT) and the widespread enthusiasm of both theoreticians and practitioners, the broader transition to Industry 4.0 (I4.0) in major industries appears imminent. This empirical study analyzes business data from 1140 automotive companies operating in Europe, utilizing various business intelligence platforms and employing decision tree analytics to establish connections between enablers, drivers, company size, and financial resources. The goal is to identify persistent barriers hindering the rational transition to Industry 4.0. The findings reveal an uneven transformation within the industry nexus. While larger companies possess the financial means to allocate collective intelligence, technical resources, and drive necessary for fulfilling I4.0 requirements, smaller members of the nexus lag behind despite their enthusiasm and intent. This imbalanced evolution poses a threat to the comprehensive transformation required for realizing all the benefits of Industry 4.0 within the sector. The primary discovery indicates that small to medium-sized enterprises do not exhibit the same rates of Industry 4.0 adoption, a lag highly correlated with their available financial and human resources for digital transition. The decision tree proposed in this study offers guidelines for achieving an Industry 4.0-compliant nexus. Given its diversity and substantial global impact, the case study from the automotive industry proves intriguing and may later be generalized to other sectors. The study’s outcome could empower engineering managers and researchers to implement, execute, and assess the impact of digital strategies based on the financial capabilities of industrial institutions.

Laser shock peening (LSP) uses plasma shock waves to induce compressive residual stress at the surface of a component which has the potential to improve its fatigue properties. For AM parts, the existence of internal defects, surface roughness, and tensile residual stresses leads to noticeably lower fatigue strength compared to materials produced through conventional processes. Furthermore, there is a tendency for greater scatter in the fatigue behavior of these parts when compared to traditionally manufactured components. In this study, the effect of LSP on the roughness and fatigue behavior of Ti-6Al-4V alloy constructed through Laser Powder Bed Fusion (L-PBF) technique was investigated. Two types of samples were designed and tested: as-built surface air foil samples for four-point bending tests and machined surface straight gage samples for uniaxial fatigue testing. Two sets of process parameters, optimized and non-optimized, were also used for the fabrication of each sample type. It was found that LSP had negative effects on the smooth (i.e., machined) surface samples, whereas for as-built surfaces the roughness was enhanced by decreasing the sharpness of the deep valleys and partially remelting the loosely bonded particles on the peaks. It was found that the scatter of the fatigue data decreased for optimized machined samples, while no clear improvement was observed in their lives. However, all non-optimized samples showed improvements in fatigue lives after the LSP process.