The Pinnacle of Industrial Coating Technology.

Defects like pinholes (small holes in the finish) or crazing (fine cracking) are typically caused by failures in process control that can be eliminated with high-quality enamel equipment. Pinholes are often caused by gases escaping from the steel during firing. A proper ground coat and a precisely controlled, multi-stage firing curve, managed by a TIMS furnace, allows these gases to escape before the glass fully fuses. Crazing is caused by a mismatch in the thermal expansion between the enamel and the metal substrate. This is prevented by using the correct enamel formulation for the specific metal and by ensuring a perfect, strong bond, which is a direct result of meticulous pretreatment and firing—core strengths of our enamel equipment.

When choosing enamel equipment, a key decision is the application method. Wet application uses a water-based slurry of enamel particles called a "slip." It is very versatile and can be used to coat complex shapes via dipping or spraying, but it requires a separate drying stage. Dry electrostatic application uses equipment similar to powder coating to apply a layer of fine glass powder. This method offers very high transfer efficiency, produces little waste, and often results in a more uniform layer. However, it can be more challenging to get coverage in recessed "Faraday cage" areas. TIMS has deep expertise in both types of enamel equipment and can help you determine the optimal process for your product.

The porcelain enameling process, which requires highly specialized enamel equipment, involves several key stages. First, the metal part undergoes a rigorous multi-stage pretreatment to be cleaned and etched. Second, the enamel coating is applied. This can be done by dipping the part, by spraying a water-based "slip," or by electrostatically applying a dry glass powder. Third, the part is moved to a drying oven to remove any moisture. The final and most critical stage is firing. The part is conveyed through a high-temperature furnace at 750-850°C (1400-1560°F), which melts the glass particles, fuses them to the metal substrate, and creates the hard, durable, vitreous surface that defines porcelain enamel.

Inconsistent color in an enamel finish is a frustrating problem, usually rooted in a lack of process control in the enamel equipment. The top three causes are: 1. Inconsistent Application Thickness: Even a small variation in the amount of enamel applied will cause the color to look different after firing. This is solved with automated or robotic applicators. 2. Inconsistent Firing Temperature: The final color of many pigments is highly dependent on the exact temperature and time in the furnace. Even a 5-10 degree variance can cause a noticeable shift. 3. Inconsistent Enamel Slip: In a wet process, the water content and viscosity of the enamel slip must be kept constant. A high-quality TIMS enamel equipment system uses automation to control all three of these variables, guaranteeing consistent color from batch to batch.