Fundamental Study on Electrode Performance of Diamond Composite for EDM
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-01-01 |
| Journal | International Journal of Electrical Machining |
| Authors | Shun-ichiro Tsuetani, Koki Yoshida, Akira Okada |
| Institutions | Okayama University |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond Composites for High-Precision EDM
Section titled âTechnical Documentation & Analysis: Diamond Composites for High-Precision EDMâExecutive Summary
Section titled âExecutive SummaryâThis study investigates the use of diamond composites (Cu-Dia, Ag-Dia) as high-performance electrodes for Electrical Discharge Machining (EDM), confirming the potential of diamond materials when surface quality and machining parameters are optimized.
- Core Challenge: Initial diamond composites exhibited extremely high surface roughness (up to 182 ”mRz), leading to unstable discharge and high electrode wear ratio compared to pure copper.
- Wear Mechanism Identified: The metal matrix (Cu/Ag) is preferentially removed by discharge heat, exposing diamond grains. These exposed grains graphitize, becoming conductive and causing discharge concentration.
- Surface Solution: Applying a thick copper layer (Cu-pack) reduced surface roughness to 1.6 ”mRz, stabilizing the discharge and matching the EDM characteristics of pure Cu.
- Optimized Performance: Under specific low-wear conditions (small discharge area, low current: 3A, 16 ”s), the Cu-Dia composite achieved an electrode wear ratio approximately 50% lower than that of pure copper.
- Material Practicability: Cu-Dia composite is confirmed as a practical electrode material for high-precision EDM applications requiring small discharge areas and low electrode wear.
- 6CCVD Advantage: 6CCVD specializes in providing highly polished Polycrystalline Diamond (PCD) and custom metalization, directly addressing the critical surface roughness and composite structure requirements identified in this research.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results, focusing on material properties and optimized EDM conditions.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Cu-Dia Thermal Conductivity (λ) | 380 | W/(mK) | High thermal sink capability. |
| Ag-Dia Thermal Conductivity (λ) | 580 | W/(mK) | Highest thermal conductivity tested. |
| Cu-Dia CTE (α) | 8.4 | 10-6/K | Low coefficient of linear thermal expansion. |
| Ag-Dia CTE (α) | 10.2 | 10-6/K | Low coefficient of linear thermal expansion. |
| Raw Cu-Dia Surface Roughness (Rz) | 87.7 | ”m | Initial, unpolished composite surface. |
| Cu-pack Surface Roughness (Rz) | 1.6 | ”m | Polished surface with thin Cu layer (required for stable discharge). |
| Optimized Discharge Current (ie) | 3 | A | Condition [II]: Small discharge area/low wear. |
| Optimized Discharge Duration (te) | 16 | ”s | Condition [II]: Small discharge area/low wear. |
| Optimized Discharge Area (S) | 10 | mm2 | Condition [II]: 2 x 5 mm, resulting in lowest wear ratio. |
| Open Circuit Voltage (V) | 90 | V | Used across all test conditions. |
| Cu-pack Layer Thickness | 200 | ”m | Thickness of the thin Cu surface layer applied to Cu-Dia. |
Key Methodologies
Section titled âKey MethodologiesâThe experimental procedure focused on synthesizing diamond composites and testing their performance under varying EDM conditions, followed by detailed surface analysis.
- Material Synthesis: Diamond composites (Cu-Dia, Ag-Dia) were produced by sintering metal powder (Cu or Ag) and insulated diamond grains (< 200 ”m average size) via pressing.
- Composite Composition: Cu-Dia was 60 vol.% diamond; Ag-Dia was 50 vol.% diamond.
- Surface Modification (Cu-pack): A specialized Cu-pack composite was created by pressing a thin copper plate (approx. 200 ”m thick) onto the Cu-Dia surface to achieve a lower surface roughness (1.6 ”mRz) and prevent initial diamond exposure.
- EDM Setup: A die-sinking electrical discharge machine (Sodick AP3L) was used to machine alloy tool steel (SKD11) in working oil.
- Test Conditions: Two primary EDM conditions were applied:
- Condition [I] (Wide Area/High Current): 10x10 mm2 area, 15A current, 3 ”s duration, Cathode polarity.
- Condition [II] (Small Area/Low Current - Optimized): 2x5 mm2 area, 3A current, 16 ”s duration, Anode polarity.
- Wear Measurement: Electrode wear ratio was calculated by subtracting the weight of the electrode before and after EDM.
- Surface Analysis: Discharge waveforms were monitored. EDMed surfaces were analyzed using optical imaging, height mapping, and Laser Raman Spectroscopy (532 nm excitation) to confirm the graphitization of exposed diamond grains.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the high-quality diamond materials and precision engineering services necessary to replicate, optimize, and extend the findings of this research into industrial applications requiring low-wear EDM electrodes.
Applicable Materials
Section titled âApplicable MaterialsâThe successful implementation of diamond composites for EDM relies on controlling the surface quality and ensuring high thermal properties.
| Research Requirement | 6CCVD Material Solution | Technical Rationale |
|---|---|---|
| Composite Structure (PCD) | Polycrystalline Diamond (PCD) | MPCVD PCD offers high thermal conductivity and mechanical robustness suitable for composite electrode structures. |
| High Thermal Conductivity | Optical Grade SCD | For applications requiring the absolute highest thermal performance (λ > 2000 W/(mK)) or extreme purity, SCD wafers are available up to 500 ”m thick. |
| Conductive Surface Layer | Metalized PCD/SCD | We offer custom metalization services to apply conductive layers (e.g., Au, Pt, Ti, Cu) directly onto the diamond surface, mimicking the successful Cu-pack structure. |
Customization Potential
Section titled âCustomization PotentialâThe research highlights that precise dimensions and superior surface finish are critical for stable EDM performance. 6CCVDâs capabilities directly address these needs.
- Surface Roughness Control: The paper noted that raw composites failed due to roughness (87.7 ”mRz). The successful Cu-pack required 1.6 ”mRz. 6CCVD guarantees superior polishing:
- SCD: Ra < 1 nm
- Inch-size PCD: Ra < 5 nm
- This ultra-low roughness ensures immediate discharge stability, eliminating the need for extensive pre-grinding or thick sacrificial layers.
- Custom Dimensions and Thickness: The electrodes tested were 10x10 mm and 2x5 mm. 6CCVD provides custom plates and wafers up to 125 mm (PCD) and offers precise laser cutting services to achieve any required electrode geometry.
- Metalization Services: We offer in-house deposition of critical metals (Au, Pt, Pd, Ti, W, Cu) to create custom conductive layers or bonding pads, essential for integrating diamond electrodes into complex EDM systems.
Engineering Support
Section titled âEngineering SupportâThe transition from fundamental research to industrial EDM tooling requires expert material selection to balance thermal, electrical, and mechanical properties.
- Application Expertise: 6CCVDâs in-house PhD engineering team specializes in material selection for high thermal management and extreme environment applications, including high-precision EDM and micro-machining projects.
- Process Optimization: We assist clients in selecting the optimal diamond type (SCD for purity, PCD for large area/composite structure, BDD for intrinsic conductivity) to achieve the lowest possible electrode wear ratio for similar High-Precision EDM projects.
- Global Logistics: We ensure reliable, global shipping (DDU default, DDP available) for time-sensitive research and production schedules.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond composites which are made of diamond grains and metals has high thermal conductivity and low coefficient of linear thermal expansion. Therefore, a possibility of diamond composite as electrode for EDM was highly expected. In this study, tool electrode performances of copper-diamond (Cu-Dia) composite and silver-diamond (Ag-Dia) composite in EDM die-sinking were experimentally investigated. The results show that the metal around the diamond grains in the electrode is preferentially removed during EDM under large discharge current condition, which causes the diamond grains to expose on the electrode surface. Consequently, the undulation of electrode surface increases and the discharging state becomes unstable. In order to exert maximum effect of high thermal conductivity of diamond grains and prevent its sign ificant exposure, EDM performance was investigated under the conditions with small discharge current and small discharge area. As a result, the electrode wear ratio of Cu-Dia became lower than that of pure copper. Therefore, Cu-Dia composite has a possibility as an electrode for EDM with small discharge area.