A Belgian manufacturer of insulators is pioneering new methods of milling composite parts. Work that was previously done by conventional machine tools is now handled by a flexible and highly accurate milling robot. As a result, elements of production that were relocated to China a few years ago are now returning to Belgium.
Wherever electrical current flows, there needs to be isolation. This principle was as true back in 1934 as it is now, and S.A. Isolants Victor Hallet in Brussels (Belgium) has been manufacturing custom components for electrical insulation ever since. Customers of the global company include well-known European manufacturers of rolling stock, electrical machinery, power plant components and wind turbines. Over 80 percent of output goes for export.
Now run by the fourth generation of the Hallet family, the company offers a broad product range consisting mainly of various composite materials based on epoxy or polyester resin. Until recently, only the classic methods of machining had been used. Sales Director Vincent Hallet: “We mostly use sheet material, which we machine with three-axis and five-axis CNC milling machines.”
The batch numbers of components – from one to multiple tens of thousands per year – are every bit as different as they are complex. Simple components are manufactured at the partner plant in China, whereas in Belgium they make parts with intricate three-dimensional shapes.
Over the past two years, the company has invested heavily in setting itself up for healthy growth over the long term. “We had a new production building constructed and at the same time, thought long and hard about the technology that would best supplement our machine park,” adds Hallet. Various processes came under consideration. In the end, Hallet decided to purchase a more versatile machining system: “We came to the conclusion that a milling robot offers the ultimate in flexibility whilst maximizing capacity.”
After drawing up a list of specifications, Hallet entered into discussions with various robot suppliers, including Stäubli Benelux N.V., which in turn brought VDS bvba of Proven (Belgium) on board as a partner in the project. VDS can look back on 25 years of experience in automated milling. Managing Director Lander Debruyne: “Our core competence is and always has been milling – initially with three-axis machines, then with five-axis models and now with robots. Because of the high demands our customers make in terms of precision machining, we insist on using Stäubli robots because they have set the standard in this field.”
Lander Debruyne and his team designed a processing facility for Hallet, in which a centrally positioned Stäubli six-axis TX200 robot operates six workstations. At three of these, the components are held by vacuum grippers, and at the other three by mechanical clamping devices. An automatic tool changing system with 20 tools renders sterling service. Vincent Hallet: “Up to ten different tools are used per component.”
A major advantage of this system concept lies in the high productivity of the robot: while it is milling, retooling can take place at the other five stations. And on unmanned shifts, the TX200 can work on multiple components in sequence. An exceptionally high level of accuracy is achieved. Lander Debruyne: “During the machining, the robot controller is being fed with new data every two milliseconds. Furthermore, to the best of our knowledge, the only robot in Belgium with an integrated Renishaw probe is being used in this machine.” The tool data is processed by its own controller, while the robot uses only positional data. In matters of control technology, VDS has been working in partnership with B&R for many years now. The visualization on the touch screen of the VDS control console provides information about the process.
As a milling program, VDS uses the CAM software package SprutCAM. Lander Debruyne: “SprutCAM offers versatile automated machining capabilities as well as supporting us in the design and construction of robotic milling equipment, e.g. by means of simulation and collision analysis. SprutCAM has also been useful in designing the protective features.”
The interface between the robot controller and the system controller is the real-time UniVal Drive software developed by Stäubli. This open software interface allows Stäubli kinematics to be operated by an external controller. The motion controller of the system is designated the master. In plain language, this means that VDS project engineers can program the entire system via a common controller.
For Hallet, having a system that was straightforward to operate was a key requirement. “We are not robotic experts,” stresses Vincent Hallet. This requirement is met in full by the system developed by VDS: “The system is very easy to operate, and our employees have received excellent on-site training.” If a problem crops up, VDS service engineers can check out the controller via a remote data link.
The very first component to come off the assembly line showed that the milling robot enables Hallet to produce highly complex parts to a high standard of precision in the course of a single clamping. “Only a few years ago, we expanded our production capacity in China,” says Hallet. “Now, thanks to this manufacturing technology, we are bringing elements of production back to Belgium.”
Shortly after the arrival of the milling robot, Hallet had a new fan system installed, which is connected to the robot controller and extracts air & residual dust from the raw material only from the area where a component is being processed. The next step for the company involves deploying the robot on an unmanned night shift. It will then not only perform the machining operations but also pick up the components. Vincent Hallet: “We haven’t quite reached that stage yet, but we are working towards it.” When it eventually happens, productivity will take yet another giant leap forward.