Fresnel lenses made from silicone
With exhibits in the clamping force sizes from 500 – 2,000 kN, KraussMaffei says it will demonstrate at Fakuma 2017 in hall 7, stand 7308, how flexibly its all-electric PX series as well as the hydraulic CX series can adapt to respective requirements.
All machines are equipped with the new enhanced APC plus function (Adaptive Process Control), which ensures a high process reliability and with it a uniformly high component quality. Amongst other exhibits, KraussMaffei will highlight a PX 50-180 SilcoSet machine for the production of virtually flawless Fresnel lenses made from silicone. According to the company, the manufacturing of transparent diffusion lenses, called Fresnel lenses and made from silicone material, is very challenging. Silicone or LSR, particularly highly transparent silicone, are of very low viscosity and therefore require especially high precision during injection. Thanks to the superfine moulding accuracy, the facet profile is of such high resolution that no structures are visible on the lens, says the company. In the case of this application, the modular concept of the new PX series particularly distinguishes itself. At Fakuma, the PX 50-180 SilcoSet will combine hydraulic nozzle contact force with an electric injection unit, resulting in a very high precision. The machine-to-mold connection is tight and the production is leakage-free, says KraussMaffei. Special screw seals on the shaft support this. Additionally, the spring-loaded return-flow lock of the screw guarantees secure closing behaviour during processing of low-viscosity material. The APC plus function assumes a special task with this application. It compensates for the batch fluctuations commonly encountered in LSR processing. As the process progresses, APC plus monitors the viscosity of the material and corrects the filling volume even in the shot. The process as a whole is made even more precise, while the part weight remains constant. The APC plus is also able to reliably compensate for any potential preliminary cross-linking of the silicone, says the manufacturer. The compact design of the PX 50 provides lots of space for demoulding and peripherals, as well as good accessibility. For example, an integrated industrial robot demoulds the lenses. In the next step, visual quality control is performed with regard to quality of magnification and flashing before the finished lenses are stored in magazines.