Smart Molding International 2-2020

45 www.smart-molding.com mold design S IGMA Engineering GmbH (SIG - MA) based in Aachen, Germany, joined a cross-company project for a multifunctional face mask to help preventing the spread of the corona - virus. "We noticed a high demand for pro - tective masks from the public as well as from our own employees, which made this project-cooperation highly welcome" says Thomas Klein, Manag - ing Director of SIGMA about the cur - rent situation. "Due to the successful and focused cooperation with partners such as Arburg and Polar-Form we were able to simulate the layout of the complete LSR mold within shortest time and optimized themold design for process-efficiency and robustness". More Than Just a Feasibility Study For a smooth production of the masks, Tobias Sonntag, project en - gineer at SIGMA, used SIGMASOFT® Virtual Molding to evaluate the posi - tion of the injection point, the venting system, and the thermal design even before the mold was cut. The predic - tion of the process parameters and required curing time was also an im - portant result of the simulation. "We examined a lot of different factors. But the focus was on com - ponent quality, optical properties and, of course, the safety of the user that comes with a perfect com - ponent free of air entrapments or other defects. But also, a fast and resource-saving process design was very important to us," says Sonntag about the requirements for the proj - ect and part. Energy-Efficient and Resource-Saving Through Simulation There is no need to guess how the mold reaches its thermal steady state. Since SIGMASOFT® Virtual Molding will precisely calculate the required number of cycles - the reliability of mass-production is secured. For an exact control of the temperature dis - tribution, the number of temperature sensors in the mold was increased to six and their positions were optimized based on the simulation results. This allowed a focused regulation of the heating cartridges. In addition, an opti - mal insulation of the mold reduced the required energy to a minimum - energy waste was avoided. SIGMA completed the project within 24 hours, from the mold setup to the filling calculations and the thermal lay - out. A total of four parts per cycle are in - jection molded at 180 °C from the non- postcure LSR Elastosil LR 5040 supplied by Wacker. The required symmetrical temperature pattern of the four cavi - ties was first created and optimized in a simulation using optimal insulation, six temperature sensors and regulatable heating cartridges, and then realized by Polar-Form in the mold construction. "To design a mold under pressure without component and process ref - erences is the strength of SIGMASOFT® Virtual Molding" summarizes Thomas Klein. "The partners were under enor - mous pressure because everything had to run smoothly right away. We are highly pleased that the mold ran in the computer first and mistakes were avoided. This way, an efficient process was created very swiftly. Thanks to all partners for the joint success." SIGMA Engineering GmbH www.sigmasoft.de Starting in April, SIGMA Engineering, Arburg and many other partners joint forces to work on a new project against the spread of the coronavirus. Now the production of injection molded masks made of LSR (Liquid Silicone Rubber) is running at full speed. SIGMASOFT® Virtual Molding was used to determine and optimize injection points, pressure requirements, temperature distribution, air entrapment, and the crosslinking of the LSR material. Precise and Quick Face Mask Production With Virtual Molding The fixed (left) and the moving platen (right) at 180 °C after stabilization within ten cycles