Industrial Glass Painting Technologies

In the accelerating glass sector today, serial painting of bottles and glasses is carried out with fully automatic machines. Glass products such as bottles, glasses, gift items and glassware are painted with two types of paint: organic and inorganic. Organic paints are water-based or solvent-based and two-component. Paint application can be carried out using air spray, roller printing and screen printing methods. Organic paints can be dried by air drying, oven drying or UV drying. After drying, the paint forms a hard film. Inorganic paints are water-based or solvent-based and single-component. They can also be applied as frosting blasting. With frosting blasting application, the glass is frosted and a frosted appearance is provided on the surface. Paint application can be carried out using air spray, roller printing and screen printing methods. Inorganic paints are dried at baking temperatures starting from 550°C. After paint baking, it becomes completely integrated with the glass.

Air Spray Paint Application

Glass products to be painted are loaded onto the conveyor moving at a controlled speed by an operator or robot from the loading area. The glass first passes through a flaming process to abrade its surface. In the flaming process, gases such as methane, propane and butane are used to expose the glass surface to thermal oxidation lasting less than a second with the resulting flame. The flaming process improves the ability of the paint to adhere to the surface. Following the flaming process, the product passes in front of an antistatic cleaning unit to remove static charge from the surface. The surface is cleaned electrostatically and made ready for painting. The painting process can be carried out using conventional air guns, bell guns or a disk system depending on capacity and the shape of the glass piece. With conventional air guns, when quality expectations are not high, many different colors can be applied simultaneously. This reduces stock costs and shortens packaging time. In high-capacity serial production runs, bell guns and disk systems provide paint cost savings despite rising paint prices, thanks to 80-90% transfer efficiency. Bell and disk systems provide perfect paint uniformity and quality. Due to extremely low overspray, cabinet exhaust volume decreases and cleaning requirements are reduced. The booth where paint applications are carried out can be produced in two different types: water curtain or dry filter. Nowadays, dry filter technology has progressed favorably and has become more preferred. Paint application is carried out in a positively pressurized room. Thanks to the positively pressurized room, paint application is isolated from the external environment and dust entry into the cabin is prevented. In all painting systems, the glass is rotated around its own axis during painting. Painted products enter the flash-off area. In flash-off, they remain for approximately 10 minutes for rest before the oven. The paint drying oven can be conventional or infrared. In infrared ovens, oven time is reduced by a ratio of 1/3. For example, baking time that is 20-25 minutes in classic conventional ovens is reduced to 6-8 minutes. In conventional ovens, fans are used for heat distribution. Fan circulation also causes dust to fly inside the fan. In an infrared oven, since there is no air circulation, paint baking is achieved in a dust-free environment. Glass products exiting the oven enter the cooling section and cool to hand-touch temperature. After the cooling section, glass products arrive at the unloading station. They are unloaded and packaged by an operator or robot, or transferred to a high-temperature oven.

Glass Painting Technologies in Industry 4.0

Glass painting machines, with loading and unloading performed by robots, are machines compliant with Digital Industry, the 4th Industrial Revolution or Industry 4.0 as it is defined. In the glass painting machine, through sensors communicating with each other, the conveyor and loading-unloading robots communicate and move synchronously. All glass painting machines are controlled by PLC and computer. A separate recipe can be created for each product. Important values such as how many glass products are painted per hour, paint consumption, energy consumption, thermal energy consumption, downtime and operating times can be recorded and converted into reports. Additionally, users are alerted by fault alarms and maintenance alarms based on planned maintenance periods. Through remote access, the PLC system can be accessed from an office or a different country, and data can be retrieved. Fully automatic glass painting machines, with their developing technology, can operate completely unmanned and thereby provide speed, economy, efficiency and quality. With increases in efficiency and quality, the global market share of glass products can be significantly increased.   Canay Işıkman Project Department Manager Elsisan