Analytic Study on Pulsed-Laser Polishing on Surface of NAK80 Die Steel
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-12-31 |
| Journal | Journal of the Korean Society of Manufacturing Process Engineers |
| Authors | KwanâWoo Kim, Seung-Hwan Kim, Hae-Yong Cho |
| Citations | 6 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Pulsed-Laser Polishing Methodology
Section titled âTechnical Documentation & Analysis: Pulsed-Laser Polishing MethodologyâThis document analyzes the research paper âAnalytic Study on Pulsed-Laser Polishing on Surface of NAK80 Die Steelâ to highlight the critical role of advanced laser processing methodologies, which are essential for the fabrication and surface conditioning of ultra-hard materials like 6CCVDâs MPCVD diamond.
Executive Summary
Section titled âExecutive SummaryâThe research successfully validates a Finite Element Method (FEM) approach for optimizing pulsed-laser surface polishing, a technique highly relevant to MPCVD diamond processing.
- Validated Methodology: FEM simulation using DEFORM-3D was successfully verified against experimental results for predicting the thermal effects (Heat Affected Zone and molten zone) of pulsed Nd:YAG laser processing.
- Relevance to Diamond: The paper explicitly notes that laser polishing is primarily used for diamond and optical articles, confirming the direct applicability of this validated methodology to 6CCVDâs Single Crystal Diamond (SCD) and Polycrystalline Diamond (PCD) products.
- Predictive Capability: The study accurately predicted the molten zone width and, critically, the molten depth (up to 41.4 ”m), a parameter difficult to measure experimentally via standard optical microscopy.
- Process Optimization: By correlating laser power (150 W to 250 W) with melt dimensions, the research provides a robust framework for selecting optimal laser conditions for precise material removal and surface conditioning.
- 6CCVD Advantage: This analytical approach is crucial for optimizing high-precision laser cutting, drilling, and surface texturing of SCD and PCD, enabling 6CCVD to deliver complex, custom-engineered diamond solutions.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the simulation and experimental validation of the pulsed-laser polishing process.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Laser Type | Nd:YAG | N/A | Pulsed Laser Source used for polishing |
| Power Range Tested | 150 to 250 | W | Variable condition (Cases 1, 2, 3) |
| Repetition Rate | 50 | kHz | Fixed condition |
| Pulse Duration | 30 | ns | Fixed condition |
| Beam Diameter (Approx.) | 370 | ”m | Modeled heat source diameter |
| Scan Speed | 1000 | mm/s | Laser transfer speed |
| NAK80 Melting Threshold | 1500 | °C | Assumed temperature for surface polishing |
| Max Predicted Melt Width (Case 3) | 348.6 | ”m | Simulation result at 250 W |
| Max Experimental Melt Width (Case 3) | 338.49 | ”m | Experimental result at 250 W |
| Max Predicted Melt Depth (Case 3) | 41.4 | ”m | Simulation result at 250 W (Difficult to measure experimentally) |
| Simulation âOnâ Steps | 20 | N/A | Steps per pulse for heat input |
| Simulation âOffâ Steps | 2 | N/A | Steps per pulse for cooling |
Key Methodologies
Section titled âKey MethodologiesâThe research utilized a combined analytical and experimental approach to validate the thermal effects of pulsed-laser surface polishing.
- Material Characterization: Thermal properties (thermal conductivity and specific heat) of NAK80 Die Steel were measured using a thermal diffusivity measuring device (NETZSCH, LFA 457) across a temperature range (0.373 K to 1.273 K) for input into the FEM model.
- FEM Modeling: The commercial software DEFORM-3D (using the MO function) was employed to simulate the heat transfer and thermal effects of the pulsed laser on a rectangular specimen (12.8 mm x 3 mm x 2 mm).
- Laser Heat Source Modeling: The laser beam was modeled as a circular cylinder heat source with a Gaussian-like power density profile, featuring an approximate diameter of 370 ”m.
- Pulsed Boundary Conditions: To accurately model the pulsed nature of the Nd:YAG laser (50 kHz, 30 ns pulse duration), the simulation utilized a step-wise boundary condition, dividing the process into 20 âOnâ steps (heat input) and 2 âOffâ steps (cooling/transfer).
- Experimental Setup: Experiments were conducted using a high-quality Nd:YAG laser integrated into a 5-axis milling machine setup, scanning single lines across the NAK80 specimen surface at varying power levels (150 W, 200 W, 250 W).
- Validation Measurement: Specimens were cross-sectioned perpendicular to the laser path, polished, and etched to measure the molten zone width and depth for comparison against FEM predictions.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe methodology validated in this paperâusing FEM to predict precise thermal effects of pulsed lasersâis directly applicable to the high-precision fabrication and surface finishing of MPCVD diamond. 6CCVD provides the necessary materials and engineering support to leverage this advanced processing technique.
Applicable Materials for Laser Processing
Section titled âApplicable Materials for Laser ProcessingâThe high thermal stability and hardness of diamond necessitate precise, non-contact methods like pulsed-laser processing for shaping and surface modification. 6CCVD offers materials optimized for these applications:
| Material | Application Focus | Key Features for Laser Processing |
|---|---|---|
| Optical Grade SCD | High-power optics, quantum applications, high-precision tooling. | Ultra-low defect density, superior thermal conductivity, ideal for creating precise features (e.g., waveguides, NV centers) via focused laser ablation. |
| High-Purity PCD | Large-area heat spreaders, wear parts, wide-area tooling. | Plates/wafers up to 125 mm, allowing for large-scale surface texturing or polishing using validated laser scanning paths. |
| Boron-Doped Diamond (BDD) | Electrodes, sensors, specialized thermal management. | Tunable electrical properties; Boron doping can alter laser absorption characteristics, enabling specialized laser patterning. |
Customization Potential for Advanced Fabrication
Section titled âCustomization Potential for Advanced FabricationâThe research demonstrates the need for precise control over the heat-affected zone (HAZ) in the ”m range. 6CCVDâs capabilities ensure that the base material and subsequent processing meet the most stringent requirements:
- Custom Dimensions: 6CCVD provides SCD and PCD plates/wafers in custom dimensions, including inch-size PCD up to 125 mm, ready for large-scale laser patterning or polishing experiments.
- Ultra-Low Roughness Polishing: While the paper focuses on achieving a molten surface, 6CCVD specializes in post-processing, offering SCD polishing to Ra < 1nm and inch-size PCD polishing to Ra < 5nm, ensuring the final surface quality meets optical or electronic standards.
- Custom Metalization: If the laser process requires specific surface coatings to enhance energy coupling (as mentioned in related literature), 6CCVD offers in-house metalization services, including Au, Pt, Pd, Ti, W, and Cu, applied with high precision.
Engineering Support
Section titled âEngineering SupportâThe successful application of FEM for predicting melt depth validates the use of computational methods for process optimization. 6CCVDâs in-house PhD team specializes in the material science and thermal properties of MPCVD diamond and can assist clients in replicating or extending this research:
- Process Modeling Consultation: We provide expert guidance on material selection and parameter optimization for similar Pulsed-Laser Surface Modification projects, ensuring efficient material removal and minimal sub-surface damage in diamond.
- Material Selection: Assistance in choosing the optimal SCD or PCD grade based on the required laser wavelength, power density, and desired feature size.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Laser surface polishing is a polishing method for improving surface roughness using an integrated laser beam. Using a laser for surface polishing can improve the surface condition without physical contact or chemical action. Laser polishing has mainly been used to polish the surface of diamond or optical articles, such as lenses and glasses. Recently, diverse studies on laser polishing for metals have been conducted. The analytic study of laser surface polishing has been conducted with experimental trials for comparison, so that the proper conditions for laser polishing can be recommended. In this study, laser surface polishing was simulated in order to predict the heat-affected zone on the die steel depending on the power of the pulsed laser. The simulated results were verified by comparing them to those of the experimental trials. Through this study, therefore, the application of FEM to the selection of appropriate laser conditions could be possible.