CLADDING TECHNOLOGY SHANXI CO., LTDManual Cladding Hardening Treatment of Wall and Floor Tile Molds
Literature Overview and Background
This 1994 publication by Wu Jun and Wu Jingshu from Wuhan Institute of Technology addresses the surface hardening of tile molds through manual overlay welding techniques. Published in Welding Technology journal, this work reflects the early industrial application of weld overlay in ceramic tile manufacturing equipment. Tile molds, typically made of cast iron or carbon steel, experience severe adhesive and abrasive wear during the pressing and forming of ceramic tiles, leading to dimensional inaccuracies and surface defects in the finished product.
Technical Methodology and Process Design
The authors investigated manual submerged arc welding (SAW) and manual gas-shielded arc welding (GMAW) as primary overlay methods for tile mold hardening. The selection of overlay material was critical — the study compared high-carbon steel consumables (such as H08Mn2SiA with appropriate flux combinations) against austenitic stainless steel consumables (such as H08A) in terms of hardness retention, wear resistance, and adhesion to the mold base material.
| Process Parameter | Manual SAW | Manual GMAW |
|---|---|---|
| Welding current | 300-450 A | 180-280 A |
| Arc voltage | 25-35 V | 22-28 V |
| Travel speed | 100-200 mm/min | 150-300 mm/min |
| Wire diameter | 3.2-4.0 mm | 1.2-1.6 mm |
| Flux type | HJ431 or similar | N/A (shielding gas) |
| Overlay thickness per pass | 3-5 mm | 2-3 mm |
| Recommended layers | 2-3 | 2-4 |
The authors found that manual SAW provided superior deposition rates and more uniform overlay thickness, which was advantageous for large mold surfaces. However, manual GMAW offered better flexibility for complex mold geometries with intricate patterns and recessed areas.
Material Selection Analysis
The study compared several overlay material systems:
- High-carbon steel system (Cr-C): Achieved hardness of 55-62 HRC after air cooling; good abrasive resistance but limited corrosion resistance
- Austenitic stainless steel system (Cr-Ni): Achieved hardness of 35-45 HRC; excellent corrosion resistance and good adhesion to cast iron substrates
- High-speed steel system (W-Mo-V): Achieved hardness of 60-65 HRC; superior wear resistance but prone to cracking in thick sections
The authors recommended the high-carbon steel system for general tile mold applications where abrasive wear from ceramic powder was the dominant failure mode, and the austenitic stainless steel system for molds exposed to moisture or chemical environments.
Engineering Considerations and Quality Control
A critical aspect of this study was the management of the interface between the overlay layer and the cast iron substrate. Cast iron contains graphite flakes that can create voids and weak zones at the weld interface. The authors proposed several strategies:
- Surface preparation: Machining the mold surface to remove the decarburized layer and ensuring a clean, oxide-free surface
- Interlayer technique: Applying a first pass with an austenitic or nickel-based consumable to create a transition layer that prevents graphite-induced cracking
- Post-weld treatment: Controlled cooling to minimize residual stress and prevent distortion of precision mold surfaces
| Quality Requirement | Specification | Test Method |
|---|---|---|
| Surface hardness | ≥50 HRC | Rockwell hardness test |
| Overlay thickness uniformity | ±0.5 mm | Ultrasonic thickness measurement |
| Surface roughness | Ra ≤ 6.3 μm | Surface profilometer |
| Crack-free interface | No visible cracks | Dye penetrant inspection |
| Dimensional accuracy | Within mold tolerance | Coordinate measuring machine |
Study Insights and Practical Value
This literature represents an important early contribution to the application of weld overlay in the ceramic tile industry. The authors' systematic comparison of overlay materials and processes provides a practical framework for engineers dealing with mold hardening challenges. The emphasis on interface management between dissimilar materials — particularly cast iron substrates — is particularly noteworthy, as this remains a persistent challenge in overlay welding practice. The work also demonstrates that even manual welding processes, when properly controlled, can achieve satisfactory results for medium-production mold hardening applications.