Introduction
In the slip-casting process of sanitaryware ceramics, mold design determines product quality, production efficiency, and cost control. A scientifically sound and well-designed mold is essential for ensuring uniform blank shape, precise dimensions, and controllable defects. However, in practice, many issues often stem from hidden flaws introduced during the design phase: from uneven blank thickness, cracking, and deformation, to excessive dimensional deviations, difficult demolding, and accelerated mold wear—these production challenges can largely be traced back to the maturity of the mold design.
This analysis explores how mold design ultimately impacts forming quality by controlling critical factors such as slurry flow paths, drainage efficiency, and stress distribution.
The influence of mold design on forming quality manifests primarily in the following aspects:
Determining blank uniformity and structural defects
Key points: Uniformity of slurry absorption, structural stress
Impact Explanation: The design of the mold cavity, particularly the thickness ratios and curvature transitions between sections, directly determines whether slurry dehydrates and deposits uniformly under capillary action. Improper design leads to uneven thickness across different areas of the green body. During drying and firing, inconsistent shrinkage causes critical defects like cracking and deformation. Smooth inner walls reduce friction between powder and mold, enabling smoother flow and filling during pressing. This enhances green body density and uniformity. Simultaneously, effective venting design prevents gas accumulation forming bubbles or defects within the green body, ensuring consistent quality. |  |
Controlling Dimensional Accuracy and Shrinkage Rate
Key Points: Dimensional Tolerances, Shrinkage Prediction
| Impact Description: Mold dimensions are precisely scaled up after accounting for the shrinkage rate of the slip (drying shrinkage + firing shrinkage). Design must be supported by precise data on the shrinkage characteristics of the specific clay body used. Inaccurate shrinkage rate calculations directly result in post-firing dimensional deviations that fail to meet installation requirements, particularly for products requiring precise fitment like one-piece toilets. For instance, improperly designed waste pipe dimensions in a toilet bowl may cause drainage blockages or ball jams. |  |
Impact on Demolding Difficulty and Mold Lifespan
Key Points: Draft angle, parting line design
Impact Explanation:
Draft Angle: An appropriate draft angle is crucial for ensuring smooth removal of the green body from the mold without damage. Too small an angle makes demolding difficult, potentially causing green body tearing or mold wear; too large an angle alters the product's designed shape.
Parting Line Design: The positioning of the parting line (where mold halves meet) is critical. Effective design hides the line on non-visible surfaces for aesthetic integrity. Simultaneously, the precision of parting line alignment directly impacts mold closure tightness, preventing slurry leakage (mud seepage through gaps) that causes flash and increases post-molding cleanup. Mold design impacts the smoothness of the demolding process. Complex mold structures or rough inner walls may cause excessive stretching or friction during demolding, leading to defects like cracks or breakage. Furthermore, an improperly designed parting line can increase demolding difficulty or even prevent complete removal of the blank.
Impact on Production Efficiency and Cost
Key Points: Slurry intake speed, drainage efficiency
| Explanation: The mold's drainage performance directly affects slurry intake speed, i.e., the molding cycle. Optimizing drainage channels and venting systems can significantly reduce slurry intake time, increase daily output, and lower unit production costs. A well-designed mold enhances production efficiency. Simultaneously, mold durability and stability influence its service life; frequent mold replacements increase production costs. |  |
Mold design bridges product conception and mass production, serving as a critical factor in molding quality. A successful mold design must fulfill product aesthetics and functional requirements while ensuring production feasibility, efficiency, and cost-effectiveness. Any minor design flaw will be amplified during large-scale manufacturing, ultimately impacting product yield and quality.