The core of digital carving glazed Sintered Stone production lies in the integration of materials science and digital technology to simulate the texture, feel, and physical properties of natural stone.
The following is an analysis of key processes based on Industry Practice and Patented technologies:
Basic Green Body Processing
1, Raw Material Ratio and Forming
A high-quartz content formula (e.g., 30-45% quartz sand, 15-20% calcined kaolin) is used to increase viscosity at high temperatures and prevent flattening of the texture. The green body is pressed using a roll-forming machine with a capacity exceeding 33,000 tons, resulting in a width of 900-1600mm and a length of 1800-3200mm, with a thickness controlled between 6-20mm. The drying kiln temperature must be strictly controlled at 150-200°C to maintain a stable moisture content of 0.5-0.7% to prevent glaze powdering and dry particle shedding.
2, Surface Pretreatment
After pressing, the green body is brushed and dusted to ensure a clean surface. Before entering the first inkjet printer, a basic texture is printed using digital mold ink (e.g., a high-hardness ink containing silicon carbide) to provide structural support for subsequent processes.
II. Digital Carving Glazed Construction Technology
1, Compound Glazed Design
a. Base Layer Protection: The top glaze layer is applied using digital spray glazing technology. The glaze contains 50-55% base glaze (calcined kaolin 5-8 parts, potassium feldspar 30-35 parts), 25-35% solvent, and 10-20% additives (such as aluminum oxide), forming a transparent protective layer approximately 0.1-0.3mm thick.
b. Texture Generation: A peelable glaze containing a hydrophobic solvent and a water-based glaze are sequentially sprayed onto the top glaze layer, utilizing their mutually exclusive properties to create a three-dimensional concave and convex texture. The peelable glaze formula contains 4-6 parts calcined kaolin and 25-35 parts potassium feldspar, while the water-based glaze contains 7-10 parts strontium carbonate as its key ingredient.
c. Texture Enhancement: Finally, a layer of round dry granules is applied. The granules are made from 30-45 parts potassium feldspar and 10-20 parts barium carbonate, sintered at 850-950°C. A wet glaze (flow rate 33-38s/100mL) or dry spraying (application amount 70-260g/m²) creates a delicate touch and high smoothness.
d. Inkjet Technology Application
Using nano-scale 12-dimensional precision inkjet technology, combined with functional inks (such as enhanced ink containing King Kong aluminum powder), a 1:1 reproduction of the texture of natural stone is achieved. Through three inkjet processes (digital mold ink → color ink → protective glaze), a translucent effect reminiscent of real stone is achieved on a 1600×3200 mm sheet.
III. Firing and Post-Processing
1, High-Temperature Sintering Control
The green body is sintered at 1204-1214°C for 75-90 minutes, followed by a 15-minute hold in the high-temperature zone to promote crystal formation and reduce the free quartz content. The rapid cooling zone temperature must be controlled at 620-630°C. The slow cooling zone utilizes an intelligent temperature control system to limit temperature fluctuations to ±5°C to prevent cracking due to stress concentration.
Surface Finishing
The fired semi-finished product is polished. A wool brush is used to gently remove surface scum. The edge grinding accuracy is controlled to ±0.1 mm. For high-gloss products, a full glaze polishing process can be used, combined with a 2000-mesh or larger resin-based grinding block for a mirror finish. For matte products, a softer texture is achieved using fine matte dry particles (80-120 mesh).
IV. Key Technological Breakthroughs for Digital Carving Glazed Sintered Stone
1, Hydrophobic Glaze System
When the hydrophobic solvent (such as isooctane) in the glaze is peeled off and comes into contact with the aqueous phase of the water-based glaze, a micro-nanoscale concave-convex structure spontaneously forms. By adjusting the spraying order and ratio of the two glazes, the texture depth (0.05-0.3mm) and distribution density can be precisely controlled.
2, Microwave Drying Technology
Compared to traditional residual heat drying, microwave drying allows for uniform evaporation of moisture within the body, reducing pinholes in the glaze caused by localized overheating. Before applying the digital topcoat, the sintered stone body is microwave-dried to a surface temperature of 60-80°C, which improves glaze adhesion.
3, Wide Color Gamut Stability Control
For sintered stone slabs requiring hot bending, an optimized topcoat formula (such as EG05) adjusts the ratio of SiO₂ (57-59%) to Al₂O₃ (20-22%) to achieve a color difference ΔE ≤ 1 after hot bending, thus preventing devitrification caused by crystallization. 6.
V. Equipments and Quality Control
1, Core Equipment Configuration
Press Machine: Using Italian SACMI Evergreen+ (33,000-ton class) to ensure the body density is ≥2.6 g/cm³.
2, Inkjet Press: A digital inkjet press equipped with a Ricoh Gen5 printhead, with a resolution of 720 dpi or higher and support for 6 color channels (CMYK+W+V).
3. Kiln: A natural gas roller kiln with an effective length of ≥300 meters, equipped with an infrared thermometer for real-time firing curve monitoring.
4, Testing Standards for our Sintered Stone Slabs
a. Hardness: The glaze surface must meet Mohs hardness test criteria of 5 or higher (resistant to scratches by steel nails).
b. Anti-fouling: After immersion in a 5% citric acid solution for 24 hours, the surface must show no signs of penetration.
c. Flexural Strength: A three-point bending test must be ≥60 MPa, suitable for load-bearing applications such as countertops.
Through the integration of the above processes, the precise control of the entire process from the body to the carving glazed surface can be achieved. The final product reaches or exceeds the level of natural stone in terms of texture restoration, physical properties and processing adaptability; Digital carving glazed sintered stone is suitable for high-end architectural decoration, furniture countertops and other fields.