1 Introduction
2 Experimental
2.1 Stability investigations
2.1.1 Milling of Al7075 with solid carbide end mills
Diameter D | 16 mm |
Number of teeth Nt | 3 |
Corner radius rε | 1 mm |
Rake angle γ | 10 |
Clearance angle α | 10 |
Helix angle δ | 39; 40; 41° |
Feed per tooth fz | 0.1 mm |
2.1.2 Milling of AISI 4140+QT with a long cantilevered indexable insert mill
Diameter D | 20 mm |
Number of teeth Nt | 2 |
Corner radius rε | 0.8 mm |
Rake angle γ | 11 |
Clearance angle α | 9 |
Helix angle δ | 12 |
Feed per tooth fz | 0.08 mm |
2.2 Tool wear
2.2.1 Milling of Al7075 with solid carbide end mills
2.2.2 Milling of AISI 4140+QT with a long cantilevered indexable insert mill
3 Results of stability investigations
3.1 Milling of Al7075 with solid carbide end mills
3.2 Milling of AISI 4140+QT with a long cantilevered indexable insert mill
3.3 Calculated stability charts
Ktc | 600.71 N/mm2 |
Krc | 279.91 N/mm2 |
Kac | 130.58 N/mm2 |
Kte | 3.28 N/mm |
Kre | 17.89 N/mm |
Kae | 4.65 N/mm |
Ktc | 1310.2 N/mm2 |
Krc | 893.4 N/mm2 |
Kac | 148.76 N/mm2 |
Kte | 12.37 N/mm |
Kre | 46.8 N/mm |
Kae | 2.4 N/mm |
3.3.1 Milling of Al7075 with solid carbide end mills
3.3.2 Milling of AISI 4140+QT with a long cantilevered indexable insert mill
3.4 Wear stability map
3.4.1 Milling of Al7075 with solid carbide end mills
3.4.2 Milling of AISI 4140+QT with a long cantilevered indexable insert mill
4 Conclusion and outlook
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Higher process stability caused by process damping can be achieved with defined worn tools. The responsible mechanism is the larger contact area of the flank face and the workpiece, which leads to a damping force acting in the opposite direction of the tool oscillation.
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Even initial flank wear leads to a higher stability in certain areas of spindle speeds. This knowledge can be used to increase productivity in an early state of tool lifetime
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Stability peaks are reinforced by tool wear. With higher tool wear in milling aluminum new stability peaks emerge in different ranges of spindle speed.
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Wear stability maps can be used to visualize processes with a high potential to increase productivity due to process damping effects, which are the result of increased flank wear.
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A simulation based on the semi-discretization method was used to calculate the stability lobes of tools with defined wear in good agreement with experimental results.
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The results for milling aluminum Al7075 show that the stability can be increased for certain spindle speeds up to 300% compared to new sharp tools.