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72 Mircea Cozmîncă et al.
40C10
γ=0°; λ=0°
s=0.1 mm/rev
Fig.4b – The influence of speed values for 40C10 steel
From the diagrams in Figs.1 – 4 result that Fz and Cd are decreasing when
the angles γ, λ and cutting speed values are growing. When the cutting feed is
increasing, the force Fz grows and the coefficient Cd decrease. For OL44 steel,
the Fz values are smaller and the Cd are larger than those resulted for 40C10
steel.
For OL44 steel, the mz exponent is relatively constant in the 1.2 – 1.4 range.
For 40C10 steel, the mz values are variable in a larger domain, 0.8 – 1.22. For
λ=0° and γ=0° the mz exponent may achieve even the value of 1.95 (Fig.2b).
This is the reason why mz it is necessary to be reached for every material type.
The chemical composition, the nature and the structural micro constituents´
distribution of the cut material determine the plastic deformation capability.
Consequently, the cutting forces level, the values of Cd and the mz values
through which Cd amplify the cutting forces values are indirectly influenced.
4. Conclusions
1. The experimental researches regarding the values of cutting force Fz and
coefficient Cd for the four steel types were stressing the known dependencies
from angles γ and λ, cutting feed and main cutting speed.
2. The level of influence of the constructive angles γ and λ, of cutting feed
and speed takes different values depending on the material being cut.
3. Experimental tests are necessary for each material, to determine the
values for mz, mx, my exponents in order to use the models in Eqs. (1)-(4) for
the force components Fz, Fx, Fy on a cutting tooth.