In the manufacture of spare wheels, the wheels are labelled with safety information which must remain intact for the entire service life of the product. Previously, this information was affixed manually and consisted of up to six different labels, which resulted in problems with bubbles and misaligned labels. A fully automated labelling solution was therefore required.
For printing spare wheels, Tamponcolor developed a fully automated printing system with a TC 420 E/P-RT printing machine. The painted wheels are conveyed flat to the printing station and placed into workpiece holders on an electro-mechanical rotary indexing table with up to 12 stations by a handling system with NC axes, held in position and conveyed into the printing station.
The yellow surfaces with the cut-out sections for the labels are printed onto the black wheels so that the black labelling is in negative. The maximum diameter of the print image is 360mm, and the maximum cliché size is 420mm x 420mm. The solely vertical stroke movements of the printing pad are carried out via a programmable hollow shaft servomotor with linear axle and a maximum compressive force of 15,000N. The speed variations that can be realised via a servomotor in the ink transfer process from the cliché onto the wheel facilitate optimum ink transfer. The horizontal movement of the cliché and ink cup is carried out pneumatically. After printing, the drying of the labelling is carried out with hot air and the removal and transfer on the customer's own transport conveyor belts are implemented by an additional handling system with special grips. The labelling system offers a cycle time of 6s in 24h three-shift operation. For this very same task, Tamponcolor alternatively provides a system solution with a linear conveyor system with the same output volume to meet customer-specific production requirements.
It was possible to reduce the labelling costs thanks to the pad printing station. The quality problems due to incorrectly affixed labels were also eliminated. Pad printing has guaranteed reliable and durable labelling to last for the entire service life of the product.