Cutting fluid application plays an important role in the improvement of cutting performance during machining processes. However, controlling the amount of the coolant used is important in terms of its effects on the environment, human health and also on the total cost of production. Another important concern is to avoid lowering the product quality and cutting tool life when the amount of coolant is decreased. The minimum quantity lubrication (MQL) method that has been developed in recent years is suitable for meeting these needs. In this study, the MQL technique was applied in the turning of AA7075 and AA2024 aluminium alloys. The samples were subjected to four different cutting speeds (150, 187.5, 240 and 300 m/min), two different feed rates (0.1 and 0.2 mm/rev) and four different flow rates (0.25, 0.45, 0.90 and 3.25 ml/min). At the end of experiments, it was observed that increased feed rate and cutting speed had a negative effect on surface quality, while increased flow rate exhibited a positive effect on surface quality.
Direct-Powder Bed Selective Laser Processing (D-PBSLP) is considered a promising technique for the Additive Manufacturing (AM) of Silicon Carbide (SiC). For the successful D-PBSLP of SiC, it is necessary to understand the effects of process parameters. The process parameters are the laser power, scanning speed, hatching distance, and scanning strategies. This study investigates the effect of scanning strategies on the D-PBSLP of SiC and ensures that other process parameters are appropriately selected to achieve this. A numerical model was developed to obtain the proper process parameters for the investigation of scanning strategies in this work. Different scanning strategies available in the commercial Phoenix 3D printer manufactured by 3D Systems, such as concentric in–out, linear, inclined zigzag, and hexagonal, have been investigated. It was concluded that the zigzag strategy is the best scanning strategy, as it was seen that SiC samples could be printed at a high relative density of above 80% without a characteristic pattern on the layer’s top surface. SiC samples were successfully printed using different laser powers and scanning speeds obtained from the numerical model and zigzag strategy. Additionally, complex geometry in the form of triple periodic minimum surface (gyroid) was also successfully printed.
Machining processes are known to drastically impact the performance and lifetime of a component subjected to fatigue in service. Therefore, understanding the effect of manufacturing processes on surface integrity is vital to determine their suitability for any given application. As part of a wider study investigating multiple production operations, results are presented here which characterise the fatigue performance and failure mechanisms of Ti-6Al-4V specimens subject to conventional (end milling, surface grinding) and non-conventional machining processes (abrasive waterjet machining, wire electrical discharge machining, large area electron beam melting).Post process shot peening was then applied on each of the 5 different surfaces generated and the resulting fatigue response similarly evaluated. The abrasive waterjet machined specimens generally exhibited the longest fatigue life, particularly at higher applied stress (³ 700 MPa) irrespective of surface condition. Despite the difference in process mechanisms, fatigue results for the milled and wire electrical discharge machined surfaces were comparable. Examination of the fatigue specimen fracture surfaces however, revealed that the locations of crack initiation were inconsistent for the different processes and conditions assessed. In general, post process shot peening increased the fatigue strength / life of all the evaluated specimens, regardless of the base machining operation.
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