3D wire embedding: Innovative solution from ruhlamat
In recent years, the demand for heatable plastic surfaces has grown steadily in many sectors. Examples can be found above all in the automotive sector: Especially in the winter months, camera systems, headlights, lidar systems or elements of radar sensor technology required for autonomous and semi-autonomous driving regularly freeze. For example, the LED technology used in modern headlight systems does not generate enough radiant energy (cold radiators), which means that additional heating is needed to defrost the headlight covers. The remedy here is integrated heating wires that automatically ensure defrosting at low temperatures. In recent years, integrated heating wires have become established as a versatile option for heating plastic surfaces. They stand out from alternatives such as vaporized surfaces, for example, in that they do not affect radar or lidar systems.
To ensure that heating wires can be installed invisibly, it is important to conceal them in existing plastic elements. Manufacturer logos and parts of the front and rear bumpers are ideal for this. However, these usually have curved surfaces, which requires a process with three-dimensional alignment for attaching the wires.
Previous solutions usually involved first applying the heating wires to a film, which was then overmolded. However, this process only works for slightly curved surfaces. Three-dimensionally shaped surfaces cannot be mapped using this method, which also sets limits on the design of plastic elements to be heated.
With 3D wire laying, there are few limits to the design of plastic covers. The XYZ 3D wire laying technology newly developed by ruhlamat integrates heating wires into already designed plastic surfaces by applying wire geometries directly to the front or back of sensor covers, front grills, emblems or bumpers. This ultimately not only leads to more precise results, but also brings considerable time and cost savings. With a diameter of between 50 and 100µm, the wires are barely visible. Reflections can be additionally prevented by a black coating.
How does 3D wire embedding work?
Compared to the conventional wire laying process, which is used for example in the production of antennas in chip cards, 3D wire laying represents an innovation. A new feature is the possibility of utilizing additional degrees of freedom by means of a 6-axis robot. This enables a depth dimension in wire laying or the robot's ability to react to curved/uneven surfaces: the robot can adapt the inclination of the wire laying head to the surface to be processed. This is important because the wire laying process can only work if the horn is aligned perpendicular to the surface being processed. To make this possible, the ruhlamat wire laying head was combined with a robot from ABB. This is equipped with the so-called Integrated Force Control package, which allows the same contact pressure to be generated at all times - this makes it possible to compensate for unevenness or deviations between the workpiece and the 3D contour.
Digression: What does Integrated Force Control mean and what are the advantages?
With the Integrated Force Control package, robot developer ABB has created a solution that enables robots to react actively to their environment. This is based on tactile sensors that constantly provide information about the environment. This information ensures that the robot adjusts its speed or deviates from the specified path, for example. Thanks to Integrated Force Control, it is thus possible to machine complex contours.
Wire laying as such is carried out with the aid of the ultrasonic wire embedding technology developed by ruhlamat. This works with an innovative ultrasonic technology that enables a fast and precise procedure: With the help of an ultrasonic generator, electrical oscillations with 70 kHz are generated, which are converted into mechanical oscillations by a piezo crystal. The sonotrode amplifies these vibrations, causing molecular and interfacial friction on the substrate. The friction between the horn, wire and substrate or plastic surface leads to partial melting of the latter. The heating wire is then placed in the molten plastic via the wire feedthrough in the sonotrode and thus integrated directly into it.
The penetration path of the wire is regulated by the contact force of the sonotrode on the surface. Precise force control is essential for a stable process. Thanks to ABB's Integrated Force Control, the robot can actively respond to uneven surfaces and adjust its path or the orientation of the wire-laying head accordingly. This makes it possible to process concave and convex contours with the 3D wire laying process.
What are the advantages of 3D wire laying?
The advantages of the innovative 3D wire laying technology lie first of all in the possibility of being able to process three-dimensional surfaces quickly and without intermediate steps. The 3D wire laying contour can either be programmed as a curve in space using the RobotWare robot control software or read in as a path from a 3D CAD file. The compact design of the robot cell is another advantage. In addition, the process can possibly be used in other sectors in the future and wherever heated plastic surfaces are required. This makes it possible to replace more cost-intensive and time-consuming methods.