A high-frequency non-resonant elliptical vibration-assisted cutting device for diamond turning microstructured surfaces
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-01-15 |
| Journal | The International Journal of Advanced Manufacturing Technology |
| Authors | Zhengjian Wang, Xichun Luo, Haitao Liu, Fei Ding, Wenlong Chang |
| Institutions | Harbin Institute of Technology, Huazhong University of Science and Technology |
| Citations | 18 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: High-Frequency EVC Diamond Turning
Section titled âTechnical Documentation & Analysis: High-Frequency EVC Diamond TurningâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the development and performance of a high-frequency non-resonant Elliptical Vibration-Assisted Cutting (EVC) device, highlighting the critical role of high-quality diamond tooling and connecting the research requirements to 6CCVDâs advanced MPCVD diamond solutions.
- High Operational Frequency: The flexure-based EVC device successfully achieved a high operational frequency of up to 5 kHz, significantly exceeding most non-resonant counterparts in diamond turning.
- Precision Tooling Requirement: The device relies on a high-precision diamond tool (0.5 mm nose radius) to generate complex microstructured surfaces, including micro-dimple arrays and two-tier sawtooth structures.
- Low Coupling & Thermal Load: The design maintained an acceptable cross-axis coupling ratio (C1: 4.71%, C2: 9.76%) and low heat generation (max 2.74 W), ensuring stable performance for ultra-precision machining.
- High Accuracy Demonstrated: Machining trials on pure copper demonstrated excellent dimensional control, achieving wavelength errors < 1.26% and height errors < 10.67% relative to designed values.
- Vibration Amplitude: The device achieved vibration amplitudes exceeding 2 ”m in both cutting and Depth-of-Cut (DOC) directions, confirming its capability for effective intermittent cutting.
- 6CCVD Value Proposition: 6CCVD specializes in the custom fabrication and ultra-polishing of Single Crystal Diamond (SCD) inserts, which are essential for replicating and advancing this high-frequency, ultra-precision EVC technology.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Operational Frequency (Max) | 5 | kHz | Non-resonant EVC working mode |
| First Natural Frequency (Cutting Direction) | 5.2 | kHz | Experimental result |
| First Natural Frequency (DOC Direction) | 8.5 | kHz | Experimental result |
| Max Heat Generation Power | 2.74 | W | At 132 V input, air-cooled condition |
| Max Input Voltage | 132 | V | Limit set by power amplifier |
| Max Vibration Amplitude | > 2 | ”m | Cutting and DOC directions |
| Cross-Axis Coupling Ratio (C1) | 4.71 | % | DOC direction actuation |
| Cross-Axis Coupling Ratio (C2) | 9.76 | % | Cutting direction actuation |
| Wavelength Machining Error | < 1.26 | % | On two-tier microstructures (Exp. 2) |
| Height Machining Error | < 10.67 | % | On two-tier microstructures (Exp. 2) |
| Surface Roughness (Ra) | 46, 66 | nm | On pure copper (Exp. 1 & 2) |
| Diamond Tool Nose Radius | 0.5 | mm | Used in preliminary machining trials |
| DOC (Depth-of-Cut) | 3 | ”m | Preliminary machining trials |
Key Methodologies
Section titled âKey MethodologiesâThe high-frequency performance of the non-resonant EVC device was achieved through optimized mechanical design and rigorous testing protocols:
- Flexure Hinge Design: The device utilized a combination of the Leaf Spring Flexure Hinge (LSFH) and the Notch Hinge Prismatic Joint (NHPJ) to maximize structural stiffness and minimize cross-axis coupling.
- FEA Optimization: Mapped meshing Finite Element Analysis (FEA) was used for static modeling and modal analysis to determine optimal dimensions, specifically:
- LSFH thickness ($l$): Confirmed at 1.3 mm to achieve a high operational frequency.
- NHPJ neck thickness ($t$): Confirmed at 0.2 mm to maintain an acceptable coupling ratio.
- Actuation System: Two low-capacitance piezo actuators were employed, driven by sinusoidal signals (up to 132 V) with variable phase lag to generate the required elliptical tool trajectory.
- Dynamic Testing: Experimental modal tests using an impact hammer and frequency sweep tests (0 to 10 kHz) were conducted to verify the first natural frequencies and determine the upper limit of the operational frequency (5 kHz).
- Machining Parameters: Preliminary diamond turning trials were conducted on pure copper with the following typical parameters:
- Tool Feed per Revolution: 5 mm/min
- Depth-of-Cut (DOC): 3 ”m
- Spindle Speed: 30 rev/min
- Metrology: Machined microstructures were measured using a white light interferometer (Zygo CP300) to quantify wavelength and height errors, confirming the deviceâs accuracy.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful implementation of high-frequency EVC relies fundamentally on ultra-precision diamond tooling. 6CCVD provides the necessary MPCVD diamond materials and engineering services to support the replication and advancement of this research, particularly for machining hard-to-machine materials (e.g., stainless steel, silicon carbide, optical glass) mentioned as future work.
Applicable Materials for EVC Tooling
Section titled âApplicable Materials for EVC Toolingâ| Application Requirement | 6CCVD Material Recommendation | Technical Rationale |
|---|---|---|
| Ultra-Precision Cutting Edge (Required for Ra < 66 nm) | Optical Grade Single Crystal Diamond (SCD) | Highest purity and lowest defect density are essential for achieving the sharpest cutting edges and minimizing tool wear during high-frequency intermittent contact. |
| Advanced Functional Surfaces (Future work on SiC, optical glass) | High-Purity SCD Substrates | SCD is the only material capable of ultra-precision turning brittle materials like optical glass and silicon without catastrophic failure. |
| Specialized Tooling/Monitoring (Potential for in-situ sensing) | Heavy Boron-Doped Diamond (BDD) | BDD offers excellent electrical conductivity, allowing for potential integration of sensing elements or specialized electrochemical processes within the EVC tool holder. |
Customization Potential for EVC Systems
Section titled âCustomization Potential for EVC Systemsâ6CCVDâs in-house manufacturing capabilities are perfectly aligned to meet the stringent dimensional and material requirements of high-frequency EVC devices:
- Custom Tool Geometries: The paper utilized a 0.5 mm nose radius tool. 6CCVD provides custom SCD tool blanks and inserts with precision laser cutting to match any required nose radius or complex geometry for EVC systems.
- Ultra-Polishing: To ensure the highest quality surface finish (Ra < 66 nm), 6CCVD offers industry-leading polishing services:
- SCD Polishing: Ra < 1 nm.
- PCD Polishing (Inch-size): Ra < 5 nm.
- Metalization for Thermal Management: The EVC device generates heat (up to 2.74 W). 6CCVD offers internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for the diamond insert, facilitating robust mounting and efficient thermal dissipation from the cutting edge to the tool holder.
- Custom Substrate Dimensions: We supply SCD and PCD plates/wafers in custom dimensions, with PCD available up to 125 mm diameter, supporting both small-scale prototype development and large-scale industrial EVC applications. Thicknesses range from 0.1 ”m to 500 ”m for active layers, and substrates up to 10 mm.
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team provides expert consultation on material selection, crystallographic orientation, and tool design optimization for high-frequency EVC and ultra-precision surface texturing projects. We assist engineers and scientists in selecting the optimal MPCVD diamond grade (SCD, PCD, or BDD) to maximize tool life and machining accuracy in demanding applications.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract In recent years, research has begun to focus on the development of non-resonant elliptical vibration-assisted cutting (EVC) devices, because this technique offers good flexibility in manufacturing a wide range of periodic microstructures with different wavelengths and heights. However, existing non-resonant EVC devices for diamond turning can only operate at relatively low frequencies, which limits their machining efficiencies and attainable microstructures. This paper concerns the design and performance analysis of a non-resonant EVC device to overcome the challenge of low operational frequency. The structural design of the non-resonant EVC device was proposed, adopting the leaf spring flexure hinge (LSFH) and notch hinge prismatic joint (NHPJ) to mitigate the cross-axis coupling of the reciprocating displacements of the diamond tool and to combine them into an elliptical trajectory. Finite element analysis (FEA) using the mapped meshing method was performed to assist the determination of the key dimensional parameters of the flexure hinges in achieving high operational frequency while considering the cross-axis coupling and modal characteristics. The impact of the thickness of the LSFH on the sequence of the vibrational mode shape for the non-resonant EVC device was also quantitatively revealed in this study. Moreover, a reduction in the thickness of the LSFH can reduce the natural frequency of the non-resonant EVC device, thereby influencing the upper limit of its operational frequency. It was also found that a decrease in the neck thickness of the NHPJ can reduce the coupling ratio. Experimental tests were conducted to systematically evaluate the heat generation, cross-axis coupling, modal characteristics and diamond toolâs elliptical trajectory of a prototype of the designed device. The test results showed that it could operate at a high frequency of up to 5 kHz. The cross-axis coupling ratio and heat generation of the prototype are both at an acceptable level. The machining flexibility and accuracy of the device in generating microstructures of different wavelengths and heights through tuning operational frequency and input voltage have also been demonstrated via manufacturing the micro-dimple arrays and two-tier microstructured surfaces. High-precision microstructures were obtained with 1.26% and 10.67% machining errors in wavelength and height, respectively.