Experiment Comparative Analysis of Feed Rate with Velocity Control in Cutting Mono Crystalline Silicon Using a Diamond Wire Saw

At a Glance

Metadata	Details
Publication Date	2024-03-29
Journal	Micromachines
Authors	Jiabin Wang, Shujuan Li, Lie Liang
Institutions	Xi’an University of Technology
Citations	4
Analysis	Full AI Review Included

Technical Documentation & Analysis: MPCVD Diamond for Advanced Slicing Applications

Executive Summary

This research successfully demonstrates the use of a Proportional-Integral (PI) controller to optimize the fixed-diamond abrasive wire sawing of monocrystalline silicon by regulating the normal cutting force ($F_n$). The findings provide critical insights for improving productivity and surface quality in hard, brittle material processing.

Feature	Achievement	6CCVD Value Proposition
Process Control	PI control maintains constant normal cutting force ($F_n$) during slicing.	6CCVD supplies the foundation: ultra-hard SCD/PCD for durable tooling (guides, dressing).
Efficiency Gain	Feed rate control reduced total cutting time by an average of 40.6%.	Enables higher throughput for next-generation substrates (SiC, GaN, Diamond).
Surface Quality	Feed rate control reduced Surface Roughness (Sa) by an average of 63.3%.	6CCVD offers SCD polishing down to Ra < 1 nm, far exceeding the Sa values reported (2.85 µm).
Optimal Control	Control of part feed rate ($V_x$) proved superior to wire saw velocity ($V_s$) control.	Critical data for designing high-precision diamond tooling and machine control systems.
Material Relevance	Focus on monocrystalline silicon slicing.	6CCVD provides high-purity SCD/PCD for advanced electronics and optical applications, including diamond substrates themselves.

Technical Specifications

The following hard data points were extracted from the experimental setup and results, focusing on the optimal control parameters and achieved surface quality.

Parameter	Value	Unit	Context
Workpiece Material	Mono-crystal silicon	N/A	Density 2.33 g/cm³, Mohs Hardness $\approx 6.5$
Abrasive Grain Size	30-50	µm	JR2-type electroplated diamond on wire
Wire Saw Diameter	0.24	mm	Total length 106 m
Nominal Wire Velocity ($V_s$) Range	0-4	m/s	Reciprocating wire saw capability
Nominal Feed Rate ($V_x$) Range	0-3	mm/min	Part feed rate capability
Reference Normal Force ($F_r$) Tested	1.7 to 3.0	N	PI Controller set points
Best Sa (Feed Rate Control)	3.16	µm	Achieved at $F_r = 2.0$ N, $V_s = 1.0$ m/s
Best Sa (Wire Velocity Control)	2.85	µm	Achieved at $F_r = 1.7$ N, $V_x = 0.75$ mm/min
Max Feed Rate (Control Test)	10	mm/min	Saturated command velocity during initial contact
Average Sa Reduction (Feed Rate)	63.3	%	Compared to constant feed rate experiments
Average Time Reduction (Feed Rate)	40.6	%	Compared to constant feed rate experiments

Key Methodologies

The experiment utilized a closed-loop control system based on a reciprocating fixed-diamond abrasive wire saw to process square monocrystalline silicon specimens.

Experimental Setup: A custom hardware platform was built, integrating a wire saw machine, DC motor drivers (for wire velocity), step motor drivers (for feed rate), and an ATI six-component dynamometer for force measurement.
Control Objective: Maintain a stable, constant normal cutting force ($F_n$) by adjusting either the part feed rate ($V_x$) or the wire saw velocity ($V_s$).
Controller Design: A Proportional-Integral (PI) controller was designed and implemented in LabView using a National Instruments PXIe-6358 data acquisition system.
Process Parameters:
- Wire Saw Tension: Regulated via an adjustment wheel, set at 0.20 MPa air source pressure.
- Wire Saw Velocity ($V_s$): Tested at 1.0, 1.5, and 2.0 m/s (constant and controlled).
- Part Feed Rate ($V_x$): Tested at 0.5, 0.75, and 1.0 mm/min (constant and controlled).
Modeling: A static normal force model, $F_n(t) = K_n V_x(t)^\alpha V_s(t)^\beta$, was developed using least squares fitting of experimental data to determine coefficients ($\alpha$, $\beta$, $K_n$).
Comparison: The performance of feed rate control and wire saw velocity control were compared based on total operation time and final surface roughness (Sa).

6CCVD Solutions & Capabilities

This research highlights the critical need for precision and stability when slicing hard, brittle materials like silicon. As the industry moves toward even harder materials (SiC, GaN, and ultimately, MPCVD Diamond itself), the demand for ultra-wear-resistant diamond tooling and high-quality substrates increases dramatically. 6CCVD is uniquely positioned to supply the materials required to replicate, extend, and surpass the precision demonstrated in this study.

Applicable Materials

To replicate or extend this research to next-generation materials (e.g., SiC or diamond wafer slicing), engineers require the highest quality MPCVD diamond:

Application Requirement	Recommended 6CCVD Material	Key Capability Match
Ultra-Wear Resistance Tooling	Optical Grade Single Crystal Diamond (SCD)	Ideal for high-precision wire guides, dressing tools, and fixtures requiring extreme hardness and low friction.
Large-Area Substrates/Fixtures	Polycrystalline Diamond (PCD)	Available in plates/wafers up to 125 mm diameter, suitable for large-scale processing equipment components.
Advanced Electronic Substrates	High-Purity SCD Wafers	SCD thickness from 0.1 µm to 500 µm, perfect for high-power electronics and quantum applications where surface integrity is paramount.
Electrochemical Sensing/Processing	Boron-Doped Diamond (BDD)	Available for applications involving electrochemical monitoring of slurry or cutting fluid dynamics.

Customization Potential

The precision required in wire sawing necessitates highly customized diamond components. 6CCVD offers comprehensive services to meet these exact specifications:

Custom Dimensions: We provide SCD and PCD plates/wafers in custom sizes, with PCD available up to 125 mm in diameter, ensuring compatibility with industrial-scale wire saw equipment.
Ultra-Low Roughness Polishing: While the paper achieved a best Sa of 2.85 µm, 6CCVD specializes in achieving superior surface finishes:
- SCD: Ra < 1 nm.
- Inch-size PCD: Ra < 5 nm.
- This level of polish is essential for minimizing friction and wear in high-speed wire guides.
Metalization Services: For integrating diamond components into complex control systems (e.g., mounting diamond guides with integrated sensors), 6CCVD offers in-house metalization using Au, Pt, Pd, Ti, W, and Cu.

Engineering Support

The successful implementation of PI control relies heavily on accurate material modeling and precise component integration. 6CCVD’s in-house PhD team provides expert consultation for projects involving:

Material selection for high-wear applications (e.g., optimizing diamond grade for wire saw guides).
Design and fabrication of custom diamond components for force sensing and control systems.
Achieving specific surface roughness and thickness requirements for advanced wafer slicing and polishing projects.

Call to Action: For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Fixed-diamond abrasive wire saw cutting is one of the most common methods for cutting hard and brittle materials. This process has unique advantages including a narrow kerf and the ability to use a relatively small cutting force. In the cutting process, controlling the main process parameters can improve the processing efficiency, obtaining a better processing surface roughness. This work designs the PI controller (Proportional-Integral controller) based on the reciprocating wire saw cutting process. The control objects are the workpiece feed rate and wire saw velocity, and the control objective is the normal cutting force. For the control trials, several reference values of various normal cutting forces were chosen. The effects of feed rate and saw velocity on the cutting surface finish and cutting time were investigated in this work using wire saw cutting analysis on a square monocrystalline silicon specimen. The results of this study showed that under a constant applied force of 2.5 N, the optimal feed rate of the diamond wire through the specimen could reduce cutting time by 42% while achieving a 60% improvement in the measured surface finish. Likewise, optimal control of the wire saw velocity could reduce cycle time by 18% with a 45% improvement in the surface finish. Consequently, the feed speed control is more effective than the wire saw velocity.

Tech Support

Original Source

DOI: https://doi.org/10.3390/mi15040473

References

2003 - Fixed abrasive diamond wire machining—Part I: Process monitoring and wire tension force [Crossref]
2003 - Fixed abrasive diamond wire machining—Part II: Experiment design and results [Crossref]
2016 - Wire sawing technology: A state-of-the-art review [Crossref]
2010 - Basic Mechanisms and Models of Multi-Wire Sawing
2016 - Experiment study on electroplated diamond wire saw slicing single-crystal silicon [Crossref]
2021 - Analysis of sawing characteristics of fine diamond wire slicing multicrystalline silicon [Crossref]
2012 - Effect of tensile properties on the abrasive wear of steel saw wires used for silicon ingot slicing [Crossref]
2015 - Wire-sawing processes: Parametrical study and modeling [Crossref]
2017 - Effect of wire vibration on the materials loss in sapphire slicing with the fixed diamond wire [Crossref]
2020 - Effect of cutting parameters on surface integrity of monocrystalline silicon sawn with an endless diamond wire saw [Crossref]