Automotive 2K Digital Touch Surface
High-Performance, Low-Stress Injection Solutions, for Advanced Automotive Digital Touch Dashboard Surfaces
A large automotive component supplier was looking to produce Advanced Digital Touch Surfaces that are to be integrated into dashboards, center consoles, door panels and more. These new modern elements are becoming more popular in EV’s and high-end ICE vehicles.
Although they eliminate many of the traditional buttons and help to minimize tooling numbers these components are much more technical to produce. They consist of a top layer (often gloss black), a middle electronics layer, and a bottom hidden touch sensitive button layer. The top and bottom layers are over-molded onto the electronics. This specific part assembly was produced using PC and PC-ABS which incorporated shot volumes of individual components as low as 0.38cc.
The part is created in a sandwich construction with the electronics in the middle. Over-moulding of hard-coated films to create smart touch surfaces is a highly technical and delicate process. The hot runner system must also accommodate the small injection volumes and tight pitch requirements of the design.
Residence and balance are also critical processing factors. Getting the process wrong may result in defective touch buttons (wont work behind screen) and discoloration of indicator button lights (for example, yellow instead of white). In these types of applications, it’s necessary to avoid sequential injection due to the number of over molded components and varying part weights. This assembly required 12 lightweight components (buttons) to be over-molded onto the cover with part volumes ranging from 0.38cc to 1.15cc. Using SVG in this type of application would be extremely challenging, if not impossible, due to the number of components and different volumes of the over-molded components. Managing the applications critical constraint issues in the part is critical to avoid sealing issues and to minimize pressure during over-molding that can cause part quality issues such as cracks or damage that can appear over time.
The digital touch dashboard assembly was manufactured in a multi-shot process in a single mold. The high-gloss black PC-ABS main cover of the assembly weighed 67g and was produced using a Mold-Masters Master-Series hot runner system using the primary injection of the injection machine. For the second shot of the PC over-molded button components, a Master-Series 12-drop hot runner system was used which utilized iFLOW manifold technology and Femto nozzles.
Mold-Masters proprietary iFLOW Manifold Technology allows for extensive design freedom for it to be optimized to each application. iFLOW manifolds aren’t restricted to the straight or 90-degree runner channels of conventional gun-drilled manifolds. Using iFLOW, we were able to create an unnaturally balanced manifold design that incorporated various runner channel diameters ranging from 5-7mm. This design flexibility allowed us to manage the injection of the different part volumes to optimize the injection pressure and prevent shear for each component. Compact Femto nozzles were able to accommodate the small injection volumes and tight pitch requirements.
In addition, an E-multi auxiliary injection unit was utilized for the 2nd shot of the over-molding due to its injection precision and repeatability. This all-electric servo-controlled unit is much more precise than the customers existing large hydraulic machines.
The Mold-Masters optimized solution worked right out of the box which provided low-stress injection and precise control producing flawless parts with minimal scrap.
Mold-Masters has extensive automotive application experience for both ICE and EV vehicles.