Machinability improvement in micro milling AlN after laser chemical milling

Processing microchannels inside laminated aluminum nitride high-temperature co-fired ceramics(AlN HTCC) packaging, a typical difficult-to-cut ceramic, can effectively solve the heatdissipation problem of integrated chips used in smart skin. In order to improve the processing efficiency and quality of AlN, the machinability of AlN after laser chemical milling(LCM) was studied through the milling force, machined surface quality, surface defects, formation mechanism, and tool wear. This study established a milling force model that can predict the milling forces of AlN and analyses the reasons for the improvements in the milling force based on experimental data and predicted data. The results from the model and experiments demonstrated that the milling force of the laser chemical milling assisted micro milling(LCAMM) decreased by 85%–90% and 85%–95%, respectively, due to the amount of removal of a single edge was more uniform and the actual inclination angle increased during the cutting process in LCAMM. Moreover, the machined surface quality improved by 65%–76% after LCM because of less tool wear, fewer downward-propagating cracks generated during each feed, and the surface removal mode transformed from intergranular fracture to transgranular fracture, which effectively reducing tool wear and improving tool life. Finally, when feed per tooth and depth of cut were 0.4 μm/z and 5 μm, the optimal machined surface quality was obtained, with a roughness of 64.6 nm Therefore, milling after LCM can improve the machinability of AlN and providing a feasibility for the high-quality and efficient machining of microchannels.

Optimization of Ti-5Al-2.5Sn Chemical Milling Process Parameters Using Taguchi Design for Enhanced Performance

One of the nontraditional manufacturing processes is the chemical machining that deals with the removal of material substances using acidic or alkaline chemical solutions. This study aimed to determine the maximum material removal rate(MRR), and minimum surface roughness(SRa) of Ti-5Al-2.5Sn alloy during chemical milling that is possible to achieve by varying the etching chemical milling parameters in terms of time, concentration of the chemical solution [hydrofluoric acid(HF) and nitric acid(HNO_(3))], and chemical milling temperature. The Taguchi method based on a statistical design of experiments(DOE) technique with an L_(16) orthogonal array is efficiently used to obtain the objective of this study and to detect optimal chemical milling parameters for the Ti-5Al-2.5Sn alloy. The experimental results were analyzed using ANOVA analysis to determine the importance of each system parameter on the response variables(MRR and SRa). The optimal process parameters were found to be at a chemical solution concentration of 22.5% HF and 17% HNO_(3), a temperature of 45 ℃, and a time of 60 min. These parameters resulted in a maximum MRR of 0.0842 mg/min and a minimum SRa of 0.30 μm. The ANOVA result signalized that the concentration of the etching acids has the most impact on both responses with contribution percentages of 81% and 67% respectively. This takes a look at the efficacy of the Taguchi technique in optimizing chemical milling procedures and offers precious insights for selecting process parameters to attain favored results.

END GRAIN ATTACK OF LD10CS PLATES DURING CHEMICAL MILLING

The end grain attack of LDIOCS aluminium alloy plates during chemical milling in hot aqueous solution of sodium hydroxide has been studied.The results show that the microsegregation of some components,i.e.Cu,Si etc.,is the main reason of the end grain at- tack,and it is affected by the conditions of heat treatment as well.The end grain attack significantly diminishes while some technical measures which are beneficial to the reduce of segregation were taken during melting and casting.