Advances in micro cutting tool design and fabrication

Microcutting is a precision technology that offers flexible fabrication of microfeatures or complex three-dimensional components with high machining accuracy and superior surface quality.This technology may offer great potential as well as advantageous process capabilities for the machining of hard-to-cut materials,such as tungsten carbide.The geometrical design and dimension of the tool cutting edge is a key factor that determines the size and form accuracy possible in the machined workpiece.Currently,the majority of commercial microtools are scaled-down versions of conventional macrotool designs.This approach does not impart optimal performance due to size effects and associated phenomena.Consequently,in-depth analysis and implementation of microcutting mechanics and fundamentals are required to enable successful industrial adaptation in microtool design and fabrication methods.This paper serves as a review of recent microtool designs,materials,and fabrication methods.Analysis of tool performance is discussed,and new approaches and techniques are examined.Of particular focus is tool wear suppression in the machining of hard materials and associated process parameters,including internal cooling and surface patterning techniques.The review concludes with suggestions for an integrated design and fabrication process chain which can aid industrial microtool manufacture.

Magnetohydrodynamic‑based Internal Cooling System for a Ceramic Cutting Tool:Concept Design,Numerical Study,and Experimental Evalidation

The efective removal of the heat generated during mechanical cutting processes is crucial to enhancing tool life and produc-ing workpieces with superior surface fnish.The internal cooling systems used in cutting inserts employ a liquid water-based solvent as the primary medium to transport the excess thermal energy generated during the cutting process.The limitations of this approach are the low thermal conductivity of water and the need for a mechanical input to circulate the coolant around the inner chamber of the cutting tool.In this context,this paper proposes an alternative method in which liquid gallium is used as the coolant in combination with a magnetohydrodynamic(MHD)pump,which avoids the need for an external power source.Using computational fuid dynamics,we created a numerical model of an internal cooling system and then solved it under conditions in which a magnetic feld was applied to the liquid metal.This was followed by a simulation study performed to evaluate the efectiveness of liquid gallium over liquid water.The results of experiments conducted under non-cooling and liquid gallium cooling conditions were analyzed and compared in terms of the tool wear rate.The results showed that after six machining cycles at a cutting speed Vc=250 m min−1,the corner wear VBc rate was 75µm with the coolant of and 48µm with the MHD-based coolant on,representing a decrease of 36%in tool wear.At Vc=900 m min−1,the corner wear VBc rate was 75µm with the coolant of and 246µm with the MHD-based coolant on,representing a decrease of 31%in tool wear.When external cooling using liquid water was added,the results showed at Vc=250 m min−1,the diference between the tool wear rate reduction with the internal liquid gallium coolant relative to the external coolant was 29%.When the cutting speed was increased to Vc=900 m min−1,the diference observed between the internal liquid gallium coolant relative to the external coolant was 16%.The study proves the feasibility of using liquid gallium as a coolant to efectively remove thermal energy through internally fabricated cooling channels in cutting inserts.