The mechanics of sawing granite with diamond wire
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-07-10 |
| Journal | The International Journal of Advanced Manufacturing Technology |
| Authors | Janusz Konstanty |
| Institutions | AGH University of Krakow |
| Citations | 17 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study provides a fundamental analysis of the mechanics of sawing granite using diamond wire (DWS), contrasting it with traditional diamond circular sawing (CS) to optimize tool formulation and machine operation for hard rock processing.
- Milder Operating Conditions: Diamond wire sawing operates under significantly milder mechanical conditions than circular sawing. Forces and pressures acting on DWS beads are an order of magnitude lower than those on CS segments.
- Reduced Chip Thickness: The maximum chip thickness (hmax) encountered by diamonds in DWS (0.13 ”m) is approximately six times less than in CS (0.81 ”m), indicating a less aggressive cutting action.
- Tool Formulation Shift: Due to the mild conditions, DWS tools require diamond crystals that are more irregular in shape and friable, promoting better retention in the matrix and free-cutting characteristics, contrary to traditional CS segment design guidelines.
- Critical Role of Rotation: Continuous wire rotation is essential for uniform bead wear. High cutting forces (resulting from excessive down-feed rates) can overcome the torsional force induced by machine pulley offset, leading to eccentric wear (ovalization) and poor tool life.
- Vibration Control: Sawing longer stone blocks is preferred, as the increased distance between the block and guide wheels reduces wire vibration amplitude and promotes the necessary wire rotation.
- Low Tension Increase: During cutting, the total increase in steel rope tension is minimal (e.g., 1.5% to 3.5% of the pre-set value), which helps prevent conical wear of the beads.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table compares typical parameters for diamond wire sawing (DWS) and circular sawing (CS), along with specific data derived from a multi-diamond wire (MDW) test on Class 1 granite.
| Parameter | DWS (MDW Test) Value | Unit | Context |
|---|---|---|---|
| Test Block Length (Lb) | 2.8 | m | Blue Night granite |
| Set Wire Tension (FT) | 2358 | N | MDW test condition |
| Linear Speed (vs) | 29 | m/s | MDW test condition |
| Down-feed Rate (vf) | 0.35 | m/h | MDW test condition |
| Cutting Rate (MDW) | 0.98 | m2/h | Calculated (163 cm2/min) |
| Beads per Unit Length (nL) | 37 | m-1 | MDW test condition |
| Bead Diameter (db) | 8.1 | mm | MDW test condition |
| Normal Force per Bead (FN) | 3.28 | N | Calculated at 0.98 m2/h |
| Friction Force per Bead (FF) | 0.35 | N | Calculated at 0.98 m2/h |
| Mean Bead Surface Pressure | 58 | kPa | Calculated, MDW test |
| Max Chip Thickness (DWS, hmax) | 0.13 | ”m | Comparative modeling |
| Max Chip Thickness (CS, hmax) | 0.81 | ”m | Comparative modeling |
| Contact Length (DWS, lc) | 518 | mm | Comparative modeling |
| Contact Length (CS, lc) | 53.5 | mm | Comparative modeling |
| Diamond Size (Typical) | 40/50 | mesh | Both DWS and CS |
| Diamond Concentration (Typical) | 25 | - | Both DWS and CS |
Key Methodologies
Section titled âKey MethodologiesâThe study employed a mechanistic modeling approach supported by industrial quantitative data to analyze the dynamics of diamond wire sawing:
- Force and Kinematic Modeling: Developed mathematical models to describe the arched shape of the cut and the array of forces (tension, weight, centrifugal, normal, friction) acting on an individual bead during high-speed cutting.
- Torque Balance Analysis: Established the torque balance equation (FF * db/2 = FT * r) to quantify the relationship between friction force, bead diameter, wire tension, and the lever arm (r) responsible for inducing bead rotation.
- Friction Force Measurement: Used empirical methods to approximate the maximum friction force per bead (FF)max by measuring the net power consumption (P = â3UI cos Ï) difference between sawing and idle running.
- Chip Thickness Calculation: Calculated the maximum (hmax) and average (havg) chip thickness for both DWS and CS based on tool kinematics (linear speed, down-feed rate, diamond concentration) to quantify diamond loading severity.
- Vibration Analysis Integration: Incorporated findings on wire vibration characteristics, noting that vibration amplitude is minimized by increasing wire linear speed, tension, and sawing shorter distances between guide wheels (i.e., longer blocks).
- Industrial Data Validation: Applied the theoretical models using real-world operational parameters (tension, speed, down-feed, current consumption) collected during multi-wire sawing of Class 1 granite to calculate specific forces (FN, FF) and pressures.
Commercial Applications
Section titled âCommercial ApplicationsâThe findings are critical for optimizing tooling and operational procedures within the stone processing industry, particularly for hard igneous rocks like granite.
- Diamond Tool Manufacturing: Provides the necessary technical basis for formulating diamond wire beads, advocating for the use of irregular/friable diamond crystals to maximize tool life and cutting capability under mild DWS conditions.
- Granite Slabbing and Squaring: Directly supports the increasing commercialization of multi-diamond wire (MDW) machines for high-yield slabbing of granite blocks, replacing older, less efficient steel shot frame saws.
- Machine Design Improvement: Guides machine manufacturers in designing pulley systems and tensioning mechanisms that ensure continuous wire rotation and minimize vibration, thereby preventing eccentric bead wear.
- Process Optimization: Enables engineers to select optimal operational parameters (linear speed, down-feed rate, wire tension) to achieve the best combination of productivity and wire life, particularly favoring lower down-feed rates to promote wire rotation.
- Troubleshooting and Maintenance: Offers diagnostic criteria (e.g., observing conical wear, monitoring current consumption) to identify and prevent common problems such as wire breakage and unsatisfactory cutting performance in production environments.
View Original Abstract
Abstract Today, wire sawing of natural stone is undergoing widespread commercialization. In addition to rock extraction and processing with single wires, composed of a multitude of diamond-impregnated beads mounted onto a steel rope, this technology is increasingly used for slabbing of granite blocks on multi-wire machines. Evolving sophistication of stone sawing equipment dictates novel tool designs and formulations. For technologists specifying bead compositions, it is a common habit to instinctively follow the circular saw segment design guidelines. A poor tool performance is often an undesirable consequence of such an approach. To meet that challenge, theoretical models of sawing granite by means of a diamond wire saw and a diamond circular saw have been presented and contrasted with respect to diamond loading conditions. The analytical treatments are supported by scarcely available industrial quantitative assessments and qualitative observations. The evaluation of cutting forces and the identification of system characteristics affecting wire vibration and wire rotation are instrumental in both machine design and tool formulation. For practitioners working with granite, the provided knowledge is also essential to diagnose and prevent problems inherent in wire sawing, such as the high incidence of wire breakage, unsatisfactory tool life and cutting capability and eccentric bead wear. Graphical abstract
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 2005 - Powder metallurgy diamond tools