Advanced Thermal Management Tooling System for Milling of Titanium Structures

The projected growth in titanium usage for commercial and military aircraft has elevated the importance of manufacturing strategies to improve machining productivity.  The high temperature strength, inherent chemical reactivity and limited thermal conductivity of titanium are the major factors contributing to poor machinability and excessive tool wear.  FEA metalcutting simulations indicate that tool surface temperatures are in excess of 1000°C at contact stresses of 3 GPa.  The metal cutting tool industry has improved tool performance by engineering the insert geometry, substrate materials, and coatings.  In addition, performance has been improved by directing metalworking coolant into the cutting zone with external nozzles to reduce tool temperatures and evacuate metal chips. Recently, an indexable milling tool system has been developed with internal coolant capability to directly apply metalworking coolants from beneath the tool/chip interface by incorporating coolant channels through the inserts.  The internally cooled tooling systems increase metal removal rates by at least 50%, while improving tool life up to 400% compared with the most advanced tooling today.  FEA metalcutting simulations indicate a significant reduction in tooling temperatures as a major factor in tool life extension.  The impact temperature reduction on fatigue of WC-Co tools and tool life extension will be discussed.  In addition, the implications for specific applications in machining titanium with these commercial tooling systems will be discussed.