Table 6.
Analysis of variance (ANOVA)—Miniature tube A *.
| Source | Average Surface Roughness (Ra) | Back Wall Dross | ||||||
|---|---|---|---|---|---|---|---|---|
| DF | SS | F | P | DF | SS | F | P | |
| X1: Pulse fequency, f (Hz) | 1 | 0.06833 | 13.72 | 0.001 | 1 | 0.3336 | 1 | 0.328 |
| X2: Pulse width, τ (ms) | 1 | 0.05179 | 10.4 | 0.004 | 1 | 7.0369 | 21.01 | 0.000 |
| X3: Peak power, Ppeak (W) | 1 | 0.05132 | 10.31 | 0.004 | 1 | 2.7396 | 8.18 | 0.009 |
| X4: Cutting speed, v (mm/min) | 1 | 0.05239 | 10.52 | 0.003 | 1 | 31.5700 | 94.25 | 0.000 |
| X5: Pressure, P (bar) | 1 | 0.06097 | 12.25 | 0.002 | 1 | 7.8900 | 23.57 | 0.000 |
| X1X2 | 1 | 0.60109 | 12.07 | 0.002 | 1 | 2.4436 | 7.3 | 0.012 |
| X1X4 | 1 | 0.02198 | 4.41 | 0.046 | 1 | 0.4157 | 1.24 | 0.276 |
| X1X5 | 1 | 0.00237 | 0.48 | 0.497 | 1 | 2.4123 | 7.2 | 0.013 |
| X2X3 | 1 | 0.00043 | 0.09 | 0.772 | 1 | 0.0016 | 0 | 0.946 |
| X4X5 | 1 | 0.00388 | 0.78 | 0.386 | 1 | 0.0944 | 0.28 | 0.600 |
| Curvature | 1 | 0.32965 | 66.2 | 0.000 | 1 | 3.6300 | 10.84 | 0.003 |
| Residual error | 24 | 0.11950 | - | - | 24 | 8.0389 | - | - |
| Lack of fit | 21 | 0.11254 | 2.31 | 0.268 | 21 | 7.2449 | 1.3 | 0.475 |
| Pure error | 3 | 0.00696 | - | - | 3 | 0.7940 | - | - |
* Miniature Tube A: Annealed 1.8 mm OD and 110 µm wall thickness (p-values below 0.05 are bolded).