This material has revolutionized the D series tool steels by providing higher toughness without compromising the hardness. On the same analogy of the tool geometry development, new workpiece materials have also been developed, with one example is DC 53 steel. In this context, a modified tool geometry named as Xcel insert has been developed for CBN tools.
Tool manufacturers are continuously developing new cutting tools with modified geometries/coatings/submicron grain size to improve the machinability. The use of conventional CBN tool is quite common for the said process, and it is considered as an ideal cutting material to machine hard and abrasive workpieces, due to high chemical and thermal stability along with red hotness. Hard part turning (HPT) is an established process due to its various advantages over grinding operation like high material removal rate, reduce cutting time, decrease manufacturing cost, and greater flexibility. Additionally, the turning process proved to be productive for this material along with a lower surface roughness value in comparison to the wire EDM process. The threshold value of the feed rate for the excellent performance of these inserts was less than 0.20 mm/rev.
The minimum surface roughness was 0.90 µm-Ra for the workpiece having a 40 HRC hardness level, and the same value was obtained for 60 HRC as well. The formation of a groove pattern was also noticed on the flank face. SEM images revealed complete delamination of the coating from the tool surface with adhesion and attrition wear identified as the main wear mechanisms.
At a 40 HRC hardness value, true crater wear was observed due to continuous chips sliding at the rake face while for the workpiece having a 60 HRC, discontinuous chip formation produced less prominent crater wear. Results show that the tool life, surface roughness, volume of material removed, and machining zone temperature are primarily affected by the hardness of DC53 with PCRs of ~ 96%, ~ 25%, ~ 62%, and ~ 25%, respectively. An analysis of variance (ANOVA) was conducted to statistically analyze the effect and contributions of input parameters on response variables namely tool life, surface roughness, volume of material removed, power consumption, and machining zone temperature. A two-level 4-factor full factorial design was employed entailing 16 runs. In the current work, turning of DC 53 steel was conducted via Xcel modified inserts by varying workpiece hardness levels (40 and 60 HRC), cutting speed (130 and 160 m/min), feed rate (0.07 and 0.112 mm/rev), and depth of cut (0.07 and 0.17 mm). DC 53 steel has emerged as a possible replacement of AISI D2 steel possessing competitive hardness and better toughness.
0 kommentar(er)
