September 2021

42 n FOOD AND BEVERAGE September 2021 www.drivesncontrols.com If the cap fits, paint it T he Austrian manufacturer BT-Watzke specialises in making bottle caps. Its roots date back to 1892. Originally founded as a forge, the company has evolved into a supplier of premium bottle caps for customers from small wine producers to mass bottlers. It produces around 350 million caps per year and about 85% of its production is exported to more than 40 countries including the UK, South Africa and Tanzania. Bottle caps provide both protection and decoration. Watzke offers customisation options ranging from simple top and side printing, through to sophisticated foil embossing and features such as breathing or cork ventilation holes, and tear-off strips. The company acts as a one-stop supplier, from low-cost heatshrink caps to high-quality tin caps. Options include caps made from polylaminate film or aluminium. “Many customers come to us with a template and ask whether we can reproduce the design,” explains managing director, Christian Stanzel. “The fact that we have our own engineering department is tremendously beneficial, since it allows us to cater to individual customer requirements in terms of shape, colour, logo, font and so on. If we don’t have the right tools for a pending order, we carry out a feasibility check and, if necessary, upgrade or convert the existing equipment accordingly.” “There is no other producer in the world that can manufacture the complete range of closing products at one location,”boasts electrical engineer Daniel Wolf.“We have developed a range of solutions for closing the most varied types of bottles.” Watzke rarely relies on standard machines. “We build almost everything ourselves,” confirms workshop manager, Franz Reifbäck.“It is important for us to be able to respond flexibly to customer requirements.” Currently, the company has about 100 self- built systems, including 14 used to paint the caps. Watzke recently extended one of these by adding an extra function. “Because the lateral surface areas of our twist caps require up to three coats depending on the colour, we decided to integrate a third machine into this production process to increase throughput,”Reifbäck explains. As part of the upgrade, the company decided to move from the pneumatic system it had used previously to transport blanks, to a servodrive-based technology. There were potential risks with this change because, as Reifbäck points out, bottle caps are not all alike.“Depending on whether a matt or gloss paint is applied or whether the products being transported are black or green, they behave slightly differently. And the drive technology has to respond to these small, but subtle, differences.” The project involved three processes that operate independently, but have to run synchronously. They form a unit with a paint- drying kiln through which every blank is fed. A transport chain acts as the time base for the application, determining the nominal speed for all operations that have to be carried out in the individual parts of the machine. An incremental encoder interface records the position of the chain, acting as a virtual master axis. All subsequent motion sequences are aligned automatically using cam disc functions built into the automation software – Beckhoff’s TwinCat. The behaviour of the drives, whose top speed is up to 200 cycles per minute, can be tested at slow speed after every reprogramming. Regardless of the speed the system is running at, Beckhoff AM8000 servomotors used in the upgraded machine stick to the curve set for them, synchronising the new section with the existing sections of the lateral surface painting system. It is no longer necessary for Watzke to perform reference runs every morning. The actual and target positions are transmitted via EtherCat to the servomotor terminals and Beckhoff AX5000 servo amplifiers, allowing the cam disc functions to be implemented on the servomotors. Beckhoff also supplied other equipment for the machine, including numerous EtherCat input and output terminals, an incremental encoder interface, servomotor terminals, and a brake chopper terminal. The painting process is supported by a CX5130 multicore embedded PC and four AM8000 servomotors that synchronise the attachment or detachment of cap blanks. The motors also manage the movements of a turntable. Watzke is now considering adding energy management functions to the cap-painting machine, and connecting it to an ERP system, as well as other upgrades.“Perhaps we will want to process data in real time in the future, or incorporate image processing,”Wolf suggests. n An Austrian company which claims to produce the world’s widest variety of bottle tops and caps, has upgraded one of its painting machines from a pneumatic transport system to one based on servodrives. The enhanced machine, which uses electronic cams, has delivered various benefits including an end to the need to perform reference runs every morning. BT-Watzke designs and builds almost all of its specialised bottle cap production machines in-house