Phenomenological model for drilling operation

Drilling is the oldest, most widely used manufacturing operation, but it is also quite misunderstood. As drilling accuracy and cost become crucial, a better understanding of tool behaviour is required. Unlike operations such as milling and turning, where cutting phenomena are easily observable, during drilling, the tool is confined to the material. Using a six-component dynamometer (Couetard Y (1993) Capteur de forces a deux voies et application a la mesure d'un torseur de forces. Brevet francais 93403025.5) enables the complete identification of forces and torques applied by the tool to the workpiece (Couetard Y, Cahuc O, Darnis Ph (2001) Mesure des 6 actions de coupe en fraisage grande vitesse. Third International Conference on Metal Cutting and high speed machining, Metz, 27-29 Juin, pp. 37-42). Therefore, it is possible to take into account radial components (forces and moments) which are usually neglected in models and experimental approaches (Yang et al. in Int J Mach Tools Manuf 42(2002): 299-311, 2001; Chen et al. in J Mater Process Technol 58(1996): 314-322, 1995; Joseph Mazoff. Drill point geometry. http:// www. newmantools. com/ machines/ drillpoint. html). Tool behaviour during critical phases (tool entry and exit) which impact hole quality has been studied. Correlations between six-component dynamometer signals and hole metrology (roughness and geometry specifications) imply that all of six components must be considered to interpret completely drilling phenomena. This way of characterising drill behaviour will ensure optimisation of the tool point geometry and coating according to roughness and geometry specification criteria.