Table 2.

Descriptive statistics for the variable Temperature (with and without cooling) for each combination of parameters (in °C)

Parameter	N	MV ± SD	p  = 0.05*
Cooling
Without cooling	360	45.5 ± 3.6	52.7
With cooling	360	37.5 ± 1.0	39.5
Drill geometry
Standard	360	41.5 ± 4.9	51.1
Two-step	360	41.5 ± 4.8	50.9
Drill diameter (mm)
3.4	180	40.2 ± 3.4	46.9
4.5	180	42.9 ± 5.7	54.0
2.5/3.4	180	40.5 ± 3.7	47.8
3.4/4.5	180	42.5 ± 5.5	53.3
Feed (mm/rev)
0.02	80	43.8 ± 7.6	58.7
0.04	160	42.3 ± 5.2	52.4
0.10	240	41.4 ± 4.3	49.8
0.16	160	40.3 ± 3.1	46.4
0.18	80	40.7 ± 3.7	47.9
Cutting speed (m/min)
1.18	80	41.5 ± 4.7	50.8
10.68	160	41.2 ± 4.4	49.9
33.61	240	41.9 ± 5.6	52.8
56.55	160	41.4 ± 4.3	49.9
66.05	80	41.4 ± 4.2	49.5

N number of measurements, MV mean value, SD standard deviation

* 95% upper level of confidence