Introduction
In sanitaryware production, plaster molds are critical for slip casting, with their lifespan directly impacting production costs, efficiency, and product consistency. This paper summarizes comprehensive measures to extend plaster mold longevity through design and manufacturing, standardized usage, and scientific maintenance.
I. Design and Manufacturing Phase
A mold's inherent quality determines its maximum lifespan, though it inevitably reaches the end of its service life.
Regarding gypsum powder selection, high-strength α-hemihydrate gypsum is employed. Its dense crystalline structure yields significantly higher mechanical strength than standard β-gypsum. By selecting premium brands and batches, consistent purity and performance are ensured.
Optimizing the gypsum slurry ratio—moderately increasing the paste-to-water ratio while maintaining adequate water absorption—substantially enhances mold mechanical strength and abrasion resistance. The mold's permeability must be uniformly consistent throughout, avoiding locally excessive porosity or density. This ensures uniform slurry absorption rates and minimizes localized stress.
II. Standardized Usage Process
Proper operation is key to preventing premature mold failure. Standardize mold assembly and disassembly procedures: During assembly, ensure all modules are aligned and securely locked into place to prevent edge damage from misalignment. For demolding, use compressed air or wooden/plastic tools. Never strike or pry with metal tools to prevent hard impact damage. Control slurry injection and absorption time to avoid excessive thickening of the mold body, which increases demolding difficulty and imposes expansion stress on the mold. Strictly adhere to process requirements for slurry absorption duration. Maintain relatively dry molds, as damp molds have low strength and are highly susceptible to damage during demolding. Establish a standardized mold drying protocol.
III. Scientific Maintenance
Regular maintenance is key to extending the lifespan of plaster molds. Clean promptly and treat surfaces using soft brushes or sponges to remove residual slurry, maintaining cavity smoothness. Never scrape with hard objects. Perform periodic “mold washing” using specialized cleaners to dissolve the “slurry glaze” layer formed by electrolyte accumulation from slurry, restoring water absorption properties. Minor cracks or defects occurring during use should be promptly repaired with plaster slurry or specialized repair compounds to prevent defect propagation. Minimize the use of release agents containing highly corrosive components; prioritize mild release agents that enhance mold surface hardness.
IV. Systematic Management
Treat molds as critical assets. Record production dates, usage frequency, maintenance history, and implement a rotation system. Avoid continuous high-intensity use of the same mold set, ensuring adequate drying and recovery time. Adhere to the “prepare more, use less” principle by maintaining sufficient spare molds for rotation. Establish clear criteria for mold retirement. Immediately retire molds exhibiting irreparable large cracks, critical dimensional deviations, or significantly reduced water absorption rates to prevent product quality issues.
Conclusion
Extending the lifespan of sanitary ceramic plaster molds relies not on isolated measures but on establishing a comprehensive system encompassing “design and manufacturing – standardized operation – scientific maintenance – systematic management.” By implementing the aforementioned systematic technical measures, mold service life can be increased by 30%-50% or more. This significantly reduces production costs, stabilizes product quality, and enhances overall competitiveness.