Rationalisation and the associated automation of production steps is becoming an increasingly important factor for the long-term success of a company in industry, especially in a global context. However, the investment casting process - with its individual production parts in various shapes and sizes - presents this development with great challenges. For example, an average of 1,500 different models pass through BLANK's production line within one year. This is an ambitious starting point for system developers. In 2018 BLANK set a first milestone in the direction of an automated casting system when, for the first time, casting was realised with the aid of communicating robots. Since then, the system has been further developed and today represents an important building block in the company's casting department. In a next step, the BLANK development department devoted itself to the production of the wax parts and the exploitation of the associated potential for improvement.

"The wax parts required for the production process, which are manufactured with the aid of an aluminium tool, are attached by employees to wax poles and joined to form so-called trees before they are coated with ceramic and sand in the next step, thus forming the casting mould for the subsequent casting process," explains plant developer Reinhard Diemer. "Depending on the number of pieces and the complexity of the geometry, the wax parts are either injected automatically or produced on a manual injection mould. The potential lies in high volumes of individual parts, because automation can quickly pay off here. But even with complex part geometries and simultaneously high quality requirements, automated processing can be economical," says Diemer.

During initial tests in 2019, the regular process was modified in such a way that the injection-moulded wax parts were not distributed to manual gluing stations via conveyor belt as usual, but robots instead glued the parts to the wax sticks. In the first step, a robot lifted the injected parts out of the mould and placed them in a prefabricated mould. As in the manual work sequence, another robot then grips the parts, dips them in hot wax and then glues them to the wax sticks. After a development period of about one year, Reinhard Diemer is optimistic about the pilot project. "Since the processes involved are filigree, it was important to coordinate the machines used precisely. After some fine tuning, we have succeeded in doing this". The robots have now reached a point where the rods with the wax parts can even be assembled into trees within the autonomous production cell, which requires the highest precision. The automated production cell makes this precision possible in an area that is otherwise strongly characterised by manual work steps. "The gluers estimate the distance between the parts on the rods based on years of experience," says Diemer. "The same applies to the gluing process and the assembly of the entire tree structure. Automation makes the process faster, more predictable and eliminates variations in quality".

According to Reinhard Diemer, however, whether and for which parts automation in wax bonding is worthwhile should be decided on a case-by-case basis. "For each part, a set-up effort is required to adjust the robots to the requirements of the new geometry. This must not be neglected and must be taken into account." The system is currently in operation for six series of parts and will be further expanded in the coming months.

FEINGUSS BLANK GmbH (88499 Riedlingen, Germany)
Website: www.feinguss-blank.de