This study experimentally investigates the influence of cryogenic CO₂ and dry cutting conditions on the performance of multi-coated PVD tungsten carbide ball nose inserts during high-speed milling of Inconel 718. The areas of focus were the tool life, surface roughness and wear mechanisms. For the cryogenic CO₂, a new cooling method approach was applied for a consistent cooling flow deep into the cutting point. The results revealed that the inserts under cryogenic conditions outperformed those under dry cutting where it was possible to improve tool life and surface roughness by an average of 75% and 142.8% respectively. It was also evident that the multicoated tools experienced a hardening effect under cryogenic cutting which increased its hardness as well as its wear resistance. Both cutting conditions showed similar tool failure modes which were dominated by notching and build-up-edge (BUE) on the flank face, as well as flaking on the rake face. However, dry cutting generated severe BUE which accelerated the notching and flaking, as well as the wear rate and caused the inserts to reach the end-of-life in a shorter time. The EDAX element mapping and SEM analysis on the worn inserts proved that adhesion, abrasion and coating delamination were the tool wear mechanisms under both conditions. Yet, the EDAX spectrum detected the presence of the oxygen (O) element which confirmed that the inserts experienced oxidation wear during the dry cutting process and caused them to weaken prematurely. The findings could provide other insights into different approaches of cryogenic cooling applications and their impact in high-speed cutting.

本研究通过实验研究低温 CO ₂和干切削条件对 Inconel 718 高速铣削过程中多层 PVD ​​碳化钨球头刀片性能的影响。重点领域是刀具寿命、表面粗糙度和磨损机制. 对于低温 CO ₂，一种新的冷却方法被应用于深入切割点的一致冷却流。结果表明，低温条件下的刀片优于干切削条件下的刀片，其中可以将刀具寿命和表面粗糙度分别平均提高 75% 和 142.8%。同样明显的是，多层涂层刀具在低温切削下经历了硬化效果，这增加了其硬度和耐磨性。两种切削条件都显示出类似的刀具失效模式，主要是后刀面上的缺口和积屑瘤 (BUE) 以及前刀面上的剥落。然而，干切削产生了严重的 BUE，加速了缺口和剥落，以及磨损率，导致刀片在更短的时间内达到使用寿命。磨损刀片的 EDAX 元素映射和 SEM 分析证明，粘附、磨损和涂层分层是两种条件下的刀具磨损机制。然而，EDAX 光谱检测到氧 (O) 元素的存在，这证实了刀片在干切削过程中经历了氧化磨损并导致它们过早减弱。这些发现可以为低温冷却应用的不同方法及其对高速切割的影响提供其他见解。