การประยุกต์ใช้การออกแบบการทดลองเพื่อลดปริมาณผลิตภัณฑ์เซรามิคที่แตกร้าวจากกระบวนการอบแห้ง

Abstract

Ceramic production processes are sensitive to the volatility of forming environment. To avoid defects, the production process has to be validated and controlled to be in the most optimistic condition in order to prevent them. Crack is a common defect, which can be created in any process of ceramic, especially in the drying process of ceramic. High stress from shrinkage during the ceramic's drying process is a significant factor that contributes to the crack defect in ceramic products. According to this defect, a ceramic manufacturer is facing a problem with high crack on ceramic wares after firing process which a quantity of the defect is up to 20 percent. From researching the characteristic of the defect, the main factor, which affects to initiate crack in ceramic wares, is the drying process in the leather-hard dryer that consists of 5 main factors concerned: Exhaust air flap, Ventilation zone 1, Ventilation zone 2, Temperature zone 1, and Temperature zone 2. The Fractional-Factorial Design technic is implemented to screen the significant factors affecting on initiating crack defect and reduce insignificant factors to avoid over fitting in optimization process. The optimization technic to validate the most optimal parameters of the drying process is the Central Composite Design technic. The experimental results indicate that the main factors concerned of cracking in ceramic wares are Ventilation zone 1, Ventilation zone 2, Temperature zone 1, and Temperature zone 2. The optimal parameters comprise of 49.9 degree Celsius for Temperature zone 1, 58.7 degree Celsius for Temperature zone 2, and 20 percent flap opened of both Ventilation zone 1 and 2. The implementation of these parameters in the manufacturing process of drying ceramic affect to reduce the crack ratio to approximately 6.7 percent.