Improvement of Surface Roughness of Electroless Ni-P Plated Mold by Oblique Cutting
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-06-04 |
| Journal | Journal of the Japan Society for Precision Engineering |
| Authors | Tsunehiro Nakagawa, Hirofumi Suzuki, Mutsumi Okada, Akihiro Suzuki, Shinya Morita |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Ultraprecision Oblique Cutting for Mold Surface Improvement
Section titled âTechnical Documentation & Analysis: Ultraprecision Oblique Cutting for Mold Surface ImprovementâThis documentation analyzes the research on improving the surface roughness of electroless Ni-P plated molds via oblique cutting, highlighting how 6CCVDâs advanced MPCVD diamond materials and customization capabilities directly support and enable this ultraprecision manufacturing technique.
Executive Summary
Section titled âExecutive SummaryâThe following points summarize the core findings and value proposition of the research regarding ultraprecision finishing of optical molds:
- Application Focus: Validation of oblique cutting using monocrystalline diamond tools to achieve superior surface quality on amorphous electroless Ni-P plated molds/dies used for mass-produced plastic lenses.
- Key Achievement: Successful reduction of surface roughness to an ultra-low range of 5-10 nm Rz (0.5-1 nm Ra) on Ni-P, demonstrating practical viability for high-end optics manufacturing.
- Mechanism of Improvement: Oblique cutting effectively reduces burr heightâthe primary limiting factor for achieving Rz < 10 nmâby tilting the diamond tool up to 40°.
- Material Dependence: The technique proved most effective on amorphous materials (Electroless Ni-P) compared to polycrystalline materials (Oxygen-Free Copper, Brass), confirming the importance of material homogeneity.
- Methodology: Precise control of the oblique angle was achieved using simultaneous 3-axis (X, Y, Z) control on a 4-axis ultraprecision machine, allowing for geometric accuracy in non-spherical cutting.
- 6CCVD Relevance: The research relies entirely on high-quality monocrystalline diamond tools and ultraprecision substrates, materials that are core offerings of 6CCVD.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table extracts critical hard data and performance metrics from the experimental results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Achieved Surface Roughness (Rz) | 5-10 | nm | On Electroless Ni-P using optimized oblique cutting |
| Achieved Surface Roughness (Ra) | 0.5-1 | nm | On Electroless Ni-P using optimized oblique cutting |
| Tool Material | Monocrystalline Diamond | N/A | Rake Angle 0°, Relief Angle 7° |
| Tool Nose Radius (R) | 1 | mm | Standard radius used for turning |
| Depth of Cut | 2 | ”m | Constant for turning experiments |
| Oblique Angle (Ξ) Range | -10 to 40 | ° | Parameter varied to optimize burr reduction |
| Optimal Feed Rate (f) | 0.5 | ”m/rev | Lowest feed rate tested, yielding best roughness |
| Ni-P Hardness | 565 | HV | Electroless Plating (Amorphous) |
| Ni-P Young Modulus | 197 | GPa | Electroless Plating (Amorphous) |
| OFC Hardness | 100 | HV | Oxygen-Free Copper |
| OFC Young Modulus | 118 | GPa | Oxygen-Free Copper |
| Machine Control | 4-axis (X, Y, Z, C) | N/A | Ultraprecision machine (ULG-100D) |
Key Methodologies
Section titled âKey MethodologiesâThe ultraprecision oblique cutting technique relies on highly controlled machine kinematics and precise diamond tooling:
- Equipment: Experiments were conducted on a linear motor-driven 4-axis (X, Y, Z, C) controlled ultraprecision machine (ULG-100D).
- Tooling: A single crystal diamond (SCD) tool with a 1 mm nose radius, 0° rake angle, and 7° relief angle was used.
- Oblique Angle Control: The oblique cutting angle (Ξ) was geometrically controlled by setting the diamond tool horizontally and using simultaneous 3-axis (X, Y, Z) control to scan diagonally across the workpiece surface. This method allows for precise, localized control of the effective oblique angle, crucial for aspheric surfaces.
- Plunge Cut Analysis: Initial tests involved plunging the tool 1 ”m deep into Ni-P, Aluminum, and Brass at varying oblique angles (-10° to 40°) to quantify burr height reduction.
- Turning Experiment: Flat surfaces of Electroless Ni-P, Oxygen-Free Copper, and Brass were turned with a fixed 2 ”m depth of cut. The oblique angle (Ξ) and feed rate (f: 0.5 to 10 ”m/rev) were systematically varied.
- Theoretical Modeling: Experimental results were compared against the theoretical surface roughness formula for oblique cutting: Rzâ = f2 / (8 * R * cos2Ξ).
- Measurement: Surface roughness (Rz, Ra) was measured using a scanning white light interferometer, and burr profiles were analyzed using differential interference microscopy.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe success of ultraprecision machining, particularly in applications requiring nanometer-scale surface finish like optical mold fabrication, is fundamentally dependent on the quality and consistency of the diamond material used for both the tool and the substrate. 6CCVD provides the necessary materials and engineering services to replicate and advance this research.
Applicable Materials
Section titled âApplicable MaterialsâThe research confirms the necessity of high-quality, single-crystal diamond for the cutting tool. 6CCVD specializes in the production of the highest purity MPCVD diamond materials:
| Research Requirement | 6CCVD Solution | Technical Advantage |
|---|---|---|
| Ultraprecision Tooling | Optical Grade Single Crystal Diamond (SCD) | Provides the necessary purity, hardness, and structural integrity for fabricating the 1 mm nose radius tool required for nanometer-scale finishing. |
| Mold Substrates | High Purity Polycrystalline Diamond (PCD) | While the paper used Ni-P plated substrates, PCD offers superior thermal conductivity and stiffness, making it an ideal base material for high-performance molds requiring plating or direct diamond turning. |
| Advanced Applications | Boron-Doped Diamond (BDD) | Available for researchers extending this work into electrochemical machining or high-wear applications where conductive diamond is required. |
Customization Potential
Section titled âCustomization Potentialâ6CCVDâs in-house engineering and fabrication capabilities directly address the specific dimensional and interface requirements of ultraprecision mold manufacturing:
- Custom Dimensions: We supply diamond plates and wafers up to 125 mm in diameter (PCD) and large-area SCD, enabling the fabrication of inch-sized optical molds and dies.
- Thickness Control: We offer precise thickness control for both SCD (0.1 ”m to 500 ”m) and PCD (0.1 ”m to 500 ”m), ensuring optimal material usage for tool blanks or substrate layers.
- Ultra-Low Roughness Polishing: To ensure the highest quality tool blanks or finished diamond molds, 6CCVD guarantees surface roughness of Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD.
- Custom Metalization: The research involves plated materials (Ni-P). 6CCVD offers internal metalization services (Au, Pt, Pd, Ti, W, Cu) for creating robust interface layers, bonding surfaces, or custom electrodes on diamond substrates.
Engineering Support
Section titled âEngineering SupportâThe research highlights the complex interplay between material properties (amorphous vs. polycrystalline) and cutting parameters (oblique angle, feed rate).
- Material Selection Expertise: 6CCVDâs in-house PhD team provides expert consultation on selecting the optimal diamond grade (SCD vs. PCD) based on the specific mold material (e.g., high-hardness Ni-P) and required cutting kinematics.
- Process Optimization: We assist engineers and scientists in defining material specifications that minimize defects and maximize tool life in demanding ultraprecision cutting projects, such as those involving complex 3-axis oblique turning.
- 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
Ultraprecision aspheric cutting process using a monocrystalline diamond tool is widely used in the manufacturing process of the optical components and their molds/dies. Plastic lenses are molded by the injection molding using an amorphous electroless Ni-P plated molds/dies and decreasing of the lens surface roughness is required. Generally, the oblique cutting is one of the methods to decrease the cutting force and the burr, and to decrease the surface roughness. In this study, the oblique cutting was applied to aspheric mold materials to decrease the surface roughness. In the experiments, plunge cut by oblique cutting was applied to the electroless Ni-P plated molds, aluminum, oxygen free copper, and brass to clarify the burr behaviors. Finally, flat surface was diamond-turned by changing the oblique angle of the tool, the cut surface was evaluated, and the effects of the oblique angle to the surface roughness were evaluated.