Micromachining of polycrystalline CVD diamond-coated cutting tool with femtosecond laser
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-01-01 |
| Journal | Journal of Advanced Mechanical Design Systems and Manufacturing |
| Authors | Xiaoxu Liu, Kohei Natsume, Satoru Maegawa, Fumihiro ITOIGAWA |
| Institutions | Nagoya Institute of Technology |
| Citations | 14 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Femtosecond Laser Micromachining of CVD Diamond Tools
Section titled âTechnical Documentation & Analysis: Femtosecond Laser Micromachining of CVD Diamond ToolsâExecutive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates the use of femtosecond Pulse Laser Grinding (fs-PLG) for sharpening CVD diamond-coated cutting tools, offering a critical advantage over traditional nanosecond (ns) laser processing.
- High-Quality Edge Formation: fs-PLG achieved an extremely sharp tool edge with a radius of curvature of approximately 1 ”m, comparable to ns-PLG results.
- Thermal Damage Suppression: The primary finding is that fs-PLG effectively suppresses negative microstructural changes (graphitization and crystallinity deterioration) caused by the thermal impact inherent in ns-PLG.
- Microstructure Preservation: Raman spectroscopy confirmed that the diamond peak of the fs-PLG processed surface showed almost no negative change, maintaining crystal quality, unlike the ns-PLG surface which exhibited clear graphitization (increased G band).
- Optimal Processing Parameters: The most suitable conditions identified for high-quality fs-PLG were 7 W laser power, 60 mm/s scanning speed, and a 20° processing angle.
- Surface Roughness Reduction: Under optimal conditions, the surface roughness (Ra) was reduced by approximately half, achieving a value of 0.045 ”m.
- Future Direction: The study suggests that using a femtosecond laser in the ultraviolet (UV) range with a lower repetition rate could further improve processing efficiency and surface smoothness.
Technical Specifications
Section titled âTechnical SpecificationsâThis table summarizes the key quantitative data and processing parameters extracted from the research paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Material | Polycrystalline CVD Diamond (PCD) | Coating | Thickness approx. 20 ”m on cemented carbide |
| Initial Edge Roundness | 20 | ”m | As-deposited tool edge |
| Final Edge Radius (fs-PLG) | ~1 | ”m | Achieved sharpness |
| Optimal fs-PLG Power | 7 | W | Highest quality surface (Specimen 1) |
| Optimal fs-PLG Scanning Speed | 60 | mm/s | Highest speed tested |
| Optimal fs-PLG Processing Angle | 20 | ° | Required for sufficient fluence/ablation |
| Optimal fs-PLG Roughness (Ra) | 0.045 | ”m | Reduced by half from as-deposited state |
| Nanosecond PLG Roughness (Ra) | 0.024 | ”m | Smoother surface, but thermally damaged |
| Femtosecond Pulse Width | 700 | fs | Ultra-short pulse duration |
| Femtosecond Wavelength | 1045 | nm | Infrared range |
| Femtosecond Repetition Rate | 100 | kHz | High rate |
| Nanosecond Pulse Width | 7 | ns | Standard short pulse |
| Nanosecond Wavelength | 355 | nm | Ultraviolet range |
| fs-PLG Input Energy Fluence (Single Pulse) | 3.6 | J/cm2 | Low fluence, minimizing thermal effects |
| ns-PLG Input Energy Fluence (Single Pulse) | 40.8 | J/cm2 | High fluence, causing graphitization |
| Diamond Raman Peak | 1330 | cm-1 | Characteristic sharp peak in as-deposited and fs-PLG samples |
Key Methodologies
Section titled âKey MethodologiesâThe experiment focused on Pulse Laser Grinding (PLG) using ultra-short pulses to achieve cold ablation and high-precision edge shaping.
- Material Selection: Commercial cemented carbide tools coated with approximately 20 ”m thick Polycrystalline CVD Diamond (PCD) were used (CVDD tool).
- Laser System: An ultra-short pulse fiber-based femtosecond laser was utilized, operating at 700 fs pulse width, 1045 nm wavelength, and 100 kHz repetition rate.
- Focusing and Beam Geometry: A long focal distance lens (100 mm focal length) was used to create a longitudinal focused laser processing area (depth of focus ~1.25 mm). The focused spot diameter was approximately 50 ”m.
- PLG Process Kinematics: The tool edge was repeatedly scanned at a small processing angle (10° or 20°). The process involved 30 reciprocating scans per feed step.
- Feeding Mechanism: The tool was moved horizontally in the x-y direction with a feed step of 2 ”m, repeated 5 times, to gradually grind the diamond coating.
- Comparative Analysis: The optimal fs-PLG condition (7 W, 60 mm/s, 20°) was compared against a conventional nanosecond Nd:YAG laser PLG condition (7 ns, 355 nm, 3 W, 30 mm/s, 4.5°).
- Characterization:
- Edge sharpness and straightness were evaluated using Scanning Electron Microscopy (SEM).
- Surface roughness (Ra) and processed angle (Ξ) were measured using Laser Microscopy (LEXT OLS4100).
- Microstructural changes (graphitization) were detected using Raman Spectroscopy (532 nm excitation).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the foundational MPCVD diamond materials necessary to replicate, optimize, and scale the high-precision micromachining techniques demonstrated in this research. Our capabilities directly address the material quality, dimensional control, and surface finishing requirements for next-generation diamond cutting tools.
| Research Requirement / Challenge | 6CCVD Solution & Capability | Value Proposition for Engineers |
|---|---|---|
| Material: High-Quality Polycrystalline CVD Diamond (PCD) | PCD Plates/Wafers: We supply high-purity MPCVD PCD plates up to 125mm in diameter. Thicknesses range from 0.1 ”m to 500 ”m, suitable for thick coatings or free-standing tool inserts. | Guarantees consistent, high-purity PCD material optimized for demanding laser ablation processes, minimizing defects that lead to premature tool failure. |
| Surface Quality: Achieving ultra-low roughness (Ra 0.045 ”m) | Precision Polishing Services: Our standard PCD polishing achieves Ra < 5 nm (for inch-size wafers). We offer SCD polishing down to Ra < 1 nm. | Provides a superior starting surface, reducing the necessary material removal steps during PLG and enhancing the final tool edge quality and lifespan. |
| Dimensional Control: Need for custom tool geometries and precise shaping. | Custom Dimensions & Laser Cutting: We offer custom dimensions and in-house laser cutting services for precise shaping, dicing, and fabrication of complex tool inserts. | Enables rapid prototyping and production of custom rake and flank faces required for specific PLG setups and tool designs. |
| Microstructure Control: Suppressing thermal damage (graphitization) during processing. | Single Crystal Diamond (SCD): For applications requiring the absolute highest thermal stability and crystal quality, our SCD material offers superior resistance to graphitization compared to PCD. | Allows researchers to extend this work using SCD, potentially achieving even sharper, more durable edges with zero thermal degradation. |
| Future Optimization: Exploring UV laser processing (355 nm) for higher absorption. | Boron-Doped Diamond (BDD): We offer custom BDD materials. BDD exhibits unique electronic and optical properties that can be tailored to enhance absorption rates for specific UV or visible laser wavelengths. | Supports advanced research into optimizing laser-material interaction by providing specialized diamond materials with tunable properties. |
| Logistics: Global supply chain for specialized materials. | Global Shipping: We offer reliable global shipping (DDU default, DDP available) for all custom diamond plates and wafers. | Ensures timely delivery of critical materials anywhere in the world, supporting international research collaborations. |
Engineering Support: 6CCVDâs in-house PhD team specializes in MPCVD growth and diamond material science. We can assist engineers and scientists with material selection, thickness optimization, and surface preparation for similar high-precision micromachining and tool sharpening projects.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
To enhance the cutting performance of chemical vapor deposit (CVD) diamond-coated tool, a short pulse laser grinding technique is applied. However, the thermal impact of a nanosecond laser damages the diamond crystallinity of the processed surface. To reduce this thermal impact, a femtosecond laser is innovatively used in this study to conduct the pulse laser grinding (PLG) of a CVD diamond-coated cutting tool, to achieve a sharpened tool edge with high quality. Furthermore, the CVD diamond tool edges processed by femtosecond and nanosecond lasers are compared based on sharpness, smoothness, and microstructure changes. The results show that a sufficient laser fluence higher than the threshold and a reduction in the pulse overlapping rate of the laser fluence of the femtosecond laser PLG could ensure a better tool edge shaping. A laser power of 7 W, processing angle of 20°, and scanning speed of 60 mm/s with roughness reduced to approximately half, are the suitable processing conditions of the femtosecond laser. From the observation of a scanning electron microscope, the tool edge processed by femtosecond laser PLG has a relatively sharp edge, with a radius of curvature around 1 Όm, similar to that of a nanosecond laser. The further magnified images reveal a distinct processed surface characteristic. The nanosecond laser-processed surface has obvious longitudinal machining marks while that of the femtosecond laser has ablated debris. Moreover, the surface microstructure change of CVD diamond by femtosecond and nanosecond laser PLG are compared using Raman spectroscopy, further confirming that femtosecond laser could successfully suppress unfavorable structural effects in CVD diamond. Based on the results, femtosecond laser has a great potential for processing higher-quality CVD diamond tool edges.