Method for assessing the thermophysical properties of the contact pair ‘tool – steel workpiece’

To The analysis of methods for evaluating the properties of contact pairs “hard -alloy coated tool-steel billet” is carried out in order to use them to increase the reliability of the choice of turning modes in the generations of CNC systems equipped with technological intelligence. It is proposed to use the value of the thermo-emf of the test pass as an indirect indicator of the properties of contact pairs composed of a coated carbide tool and a processed steel billet. Models for calculating the cutting speed based on a given tool durability period of a coated carbide tool and predicting the actual cutting tool durability period for given processing conditions are proposed by introducing into their structure an additional informative value about the properties of each contact pair - the thermo-EMF of the test pass. The conducted resistance tests of various carbide plates during the processing of P-group steels showed sufficient reliability of the proposed dependences.

Machinability investigation and sustainability assessment in hard turning of AISI D3 steel with coated carbide tool under nanofluid minimum quantity lubrication-cooling condition

The present research addresses the machinability of hardened die steel (AISI D3, 61HRC) in hard turning using multilayer (TiCN/Al2O3/TiN) coated carbide tool under nanofluid based minimum quantity lubrication-cooling condition, where no previous data are available. Power consumption, flank wear, chip morphology and surface integrity (microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness) are considered as technological performance characteristics to evaluate the machinability. Combined approach of central composite design - analysis of variance, response surface methodology and desirability function analysis have been employed respectively for experimental investigation, predictive modelling and multi-response optimization. With a motivational philosophy of “Go Green-Think Green-Act Green”, the work also deals with energy saving carbon footprint analysis and sustainability assessment to recognize the green manufacturing in the context of safer and cleaner production. under environmental-friendly nanofluid assisted minimum quantity lubrication condition. The quantitative analysis revealed that the cutting speed influenced the power consumption during hard machining (75.78%) and flank wear of coated carbide tool (45.67%); feed rate impacted the surface finish of the machined part (68.8%) significantly. Saw tooth shapes of chip produced due to cyclic cracking. Due to low percentage contribution of error (5.32% to Ra, 6.64% to VB, and 7.79% to Pc), a higher correlation coefficient (R2) was obtained with the quadratic regression model, which showed values of 0.9, 0.88 and 0.92 for surface roughness, flank wear, and power consumption, respectively. Optimization with the highest desirability (0.9173) resulted the optimum machining conditions under NFMQL at the cutting speed of 57 m/min, depth of cut 0.1 mm, feed of 0.07 mm/rev, and insert’s nose radius of 0.4 mm. As a result, under NFMQL tool life was improved by 30.8% and 22.6% in respect of flank wear and surface roughness respectively than when machining with MQL technique by adapting the optimum machining condition. Therefore, using hard nanoparticles-reinforced cutting fluid under minimum quantity lubrication condition in practical manufacturing becomes very promising to improve sustainability.

Reliability and economic analysis in sustainable machining of Monel 400 alloy

Engineering field nurtures a variety of superalloys and its wide applications due to the inherent properties of such material. The prime concern of working engineers is to explore reliability, quality, economy, and machinability analysis of these superalloys. In this work, sustainable machining of Monel 400superalloy using PVD multilayer coated carbide tool under dry turning was studied. Surface roughness (Ra, Rz, and Rq), power (P) and cutting force (Fc) were addressed as responses. The subsequent effect of cutting speed, feed and depth of cut on the responses was explored through response surface methodology (RSM), statistical analysis of variance (ANOVA) and multiple regression analysis. Details of tool wear was observed via scanning electron microscope (SEM) to know the cutting behavior at interface. Further, the reliability and economic analysis were performed to substantiate the feasibility of cutting insert. The investigation reveals that surface roughness was affected by feed and cutting speed. The increase in cutting speed uncovers lower cutting forces with improved surface finish during dry turning which further reduces the power requirement. The economic analysis shows unit production time and unit production cost based on a single insert PVD coated carbide tool under optimum value condition. The reliability analysis exposes the meantime to repair (MTTR) (5 min), mean time between failure (MTBF) (28 min), availability (84.8%), failure rate (0.03), and reliability (80.5%) for the production system.