Precise coating solution for delicate watch components
Germany's most renowned manufacturer of watches and movements places high demands on the coating solution for its filigree, highly diverse small watch parts. Ideally a system that works like clockwork. Precise performance in the smallest of spaces with a high degree of flexibility and ease of operation. In the search for a coherent system concept, two traditional companies, Hermle and Venjakob, came together.
Time never seems to stand still here. At the production site and company headquarters in Reichenbach am Heuberg in Baden-Württemberg, the medium-sized family business Hermle produces watches and movements with a 100-year tradition. Hermle is one of the most modern watch production facilities in the world and is one of the last remaining watch manufacturers. Hermle is the only full-range supplier of large mechanical watch movements in the world.
Compact, made-to-measure system required
The watch manufacturer was looking for a new solution for coating mechanical watch parts for its new plant in Reichenbach, which was built in 2021. This system was to replace the machines that were previously in use and were already getting on in years. This included a manual spray booth for special parts, an automatic coating system with an overhead conveyor system for coating watch frames and a spindle chain conveyor system for coating rotationally symmetrical watch parts. "The new system is the best way to combine everything for which we previously needed different solutions," was the customer's request. heiko Dreher, Purchasing Manager at Hermle, only had a vague idea of what such a 3-in-1 solution could look like. After in-depth discussions, Kornelius Berg, the Venjakob sales representative responsible, presented three different quotations with various options for the functionality of the new system. "We quickly came to an agreement," says Berg. the differences lay mainly in the type of conveyor systems. Heiko Dreher was impressed by the ideas and the precise elaboration of the concepts. Hermle ultimately opted for the concept of a small, compact, fully automatic coating system with an ABB painting robot and a floor conveyor with rotary drive. The conveyor system is used to pick up the carrier frames loaded with the watch parts and for cycle-controlled transportation through the individual processing stations.
Set up, install and get started
Another criterion was the space available. The function and design of the system was adapted to the dimensions of the future system location. The coating lines were delivered in just a few parts to ensure quick commissioning, another customer request. this meant that only the platform for the supply and exhaust air and the spray booth needed to be installed. "The customer even agreed to remove two walls from the room so that the system could be transported into the designated space in as large a part as possible," reports Kornelius Berg from Venjakob. A little anecdote that everyone involved will remember for a long time to come.
Special master program for autonomous operability
The system concept developed by Venjakob enables Hermle to coat a maximum variety of small parts with one system and one conveyor system. The workpiece carrier carriage is permanently installed in the rail system. The machine output (with a cycle time of 5 minutes per product carrier) was adapted to the requirements, with approx. 20 percent upward potential. The entire system is designed to be flexible and as easy to operate as possible. The Venjakob software developers wrote a special input interface for the control of the painting robot that makes it as easy as possible for the customer to create new recipes independently. "The recipe is simply copied and the various parameters, such as the dimensions of the part to be painted, the painting speed or the angle of the spray gun, are entered," says Kornelius Berg, explaining the principle. the ease of operation and adaptation to customer requirements applies to the entire system. The coating system, including the conveyor system, is controlled via a central operating system. The machine operator also only required a basic course in maintenance and servicing of the painting robot from the manufacturer ABB.
Functional sequence and process steps
The coating system conveys in an anti-clockwise direction; the loading and unloading stations are in the same position. The watch parts to be coated are hung by hand on the product carrier racks. These are placed positively on a workpiece carrier trolley of the floor conveyor and can be quickly removed again after the coating process. Before the coating process starts, the desired recipe is selected on the system's control panel and transmitted to the control system. The corresponding parameters for processing the parts are stored in the system control unit for each recipe.
Once the desired recipe has been selected, the system is started simply by pressing a start button on the control panel. The goods carrier moves into the painting booth via the floor conveyor. After the first side of the parts has been coated by the robot's spray gun, the product carrier rotates automatically via the floor conveyor's rotating device to coat the other side. then it goes to the flash-off after coating in industrial production. Two product carriers can be on the evaporation section at the same time. After 10 minutes of evaporation, the product carriers are fed into the drying channel. Drying takes place at a temperature of 80° to 120° Celsius. The length of the continuous dryer is designed so that six product carriers can be dried at the same time. The product carriers enter at 5-minute intervals and remain in the dryer for 30 minutes at a time. The subsequent cooling in industrial coating lines takes place outside the channel at room temperature for 10 minutes. The product carriers can then be easily removed from the bars of the floor conveyor at the removal station.
