1 Introduction
2 Materials and methods
2.1 Materials
2.2 Methods
2.3 PECM process
2.4 Experimental setups
2.5 PECM structuring
Process steps | Voltage, \(\textit{U}\) (V) | Feed rate, \(\textit{v}\mathrm {_{f}}\) (mm/min) | Pulse width, \(\textit{t}\mathrm {_{p}}\) (ms) | Freq. \(\textit{f}\) (Hz) | Elect. Pressure, \(\textit{p}\) (Kpa) | Elect. flow rate, \(\textit{Q}\) (l/min) | Bip. Voltage, \(\textit{U}\mathrm {_{b}}\) (V) | Bip. Pulse, \(\textit{t}\mathrm {_{bp}}\) (ms) |
---|---|---|---|---|---|---|---|---|
Step 1 | 7.4 | 0.01 | 0.5 | 25 | 500 | 24 | 2.3 | 0.3 |
Step 2 | 15 | 0.4 | 0.3 | 30 | 650 | 29 | 2.5 | 0.3 |
3 Results
3.1 Surface topography measurements
Component type | \(\textit{Rz}\)_\(\textit{x}\)(\({\upmu } \mathrm{m}\)) | \(\textit{Rz}\)_\(\textit{y}\)(\({\upmu } \mathrm{m}\)) | \(\textit{Sz}\)(\({\upmu } \mathrm{m}\)) | \(\textit{Sa}\)(\({\upmu } \mathrm{m}\)) |
---|---|---|---|---|
Tool (HFM) | 0.962 | 2.05 | 13.1 | 0.15 |
Workpiece (HFM) | 0.834 | 0.895 | 4.5 | 0.148 |
Tool (MM) | 3.66 | 3.73 | 11.6 | 0.651 |
Workpiece (MM) | 1.4 | 1.92 | 2.96 | 0.108 |
3.2 Tribological tests of the PEMed structures
4 Conclusion and outlook
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By using a complex process chain that combines surface structuring processes such as micromilling or high-feed milling with a PECM process, a procedure was identified that has high potential for modifying surfaces with functional structures.
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With regard to the geometry of the observed structures extremely fine cavities (HFM) and rounded peaks (MM) demonstrate a uniform and reproducible quality. Deviations in height as well as particles and pores on the resulting surface indicate the need for further improvement of the specific process. In addition, the study of tool cleaning to precisely remove the dark layers of dissolved material formed on the tool surface is necessary to increase process stability.
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The friction properties for the developed structures were determined in a ring compression test. The strong influence on the friction factor, with reduced values for the HFM and increased values for the MM structures, showed the potential of these new structure variants for material flow control, e.g. in forming processes.
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The investigated process chain is a promising approach for the development of new complex-shaped structure variants by means of reverse engineering. In particular, structure geometries that are difficult to machine by cutting can be processed with PECM. In addition, PECM can increase productivity for large areas or quantities compared to structuring with micromachining processes, which makes this process chain economical and thus potential attractive for mass production in industrial applications.
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In further investigations, the process limits in terms of structure shape and scale are to be determined and, based on this, new structure variants such as bionic structures could be developed and produced. In addition, the potential transfer to industrial applications is to be demonstrated on the basis of the application on complex shaped forming tools such as gears.