The company Čegan is both a manufacturer of injection-molded parts for the automotive industry and also develops and produces its own parts and products made of plastics weighing up to 4,160 g by injection molding on machines with a clamping force of up to 600 tons. The company has extensive experience with injection molding of both technical and aesthetic parts.

One of the company’s own products was a support element for terrace systems used in construction. It is a grid made of thermoplastic, on which tiles are laid. Individual grids are connected like tiles into a system. The grid is screwed onto a beam, which is placed at any height above the ground outdoors. The requirement was for the part—the grid—to have maximum stiffness and minimal deformation so that the grids could be connected into a system. The biggest challenge was to minimize the deformation of the part after molding while simultaneously achieving maximum stiffness to withstand the expected load.

For the entire product development as well as for its production, the following goals were set:

• Design the part to minimize the risk of deformation as much as possible.
• Maximize the stiffness of the part by selecting a suitable polymer combined with technological design of the part.
• Optimize the design of the part and the injection mold to minimize modifications and adjustments to the mold.
• Ensure smooth manufacturability and assembly of the parts.

The first task was to describe the current state of the part design based on basic data, injection parameters, injection, and temperature control systems.

From the simulation of the existing part design, manufacturability risks and the expected behavior of the part after molding were identified. Initial simulations predicted significant deformation, specifically bending of the part, which would greatly complicate the assembly and function of the tiles with each other. The task was to reduce the risk of deformation by modifying the part and the mold. At the same time, the design changes had to ensure trouble-free manufacturing considering the overall shape of the part. Based on the outputs from Moldflow simulations, options for modifications to the gating system, part design, and process parameters were proposed. All design and process variants were verified and compared through Moldflow simulation.

Čegan selected a combination of part design modifications, gating system, and temperature control system from all proposed options. The chosen combination was further verified with strength calculations to ensure stable part production and that the final part met all requirements.

The final part design was further verified by strength calculations using the software Simulia Abaqus, which considered the method and level of load defined by standards. A load value of 7500 N/m² was verified, as well as the part’s fixation in the assembly and other boundary conditions, i.e., support of the part, the polymer used, and the material characteristics of the polymer at 23°C and 60°C. Initial design modifications showed negative strength results. Therefore, strength checks were continuously conducted alongside design changes, with individual design modifications also verified from a strength perspective. The task was solved using the Design of Experiment method, involving more than 10 calculation iterations.

Using Moldflow simulations, the future behavior of the part after production and critical areas from the mold design perspective were described.

From the manufacturability standpoint, Moldflow simulations tested 8 options for modifying the gating and temperature control systems and their impact on the final part. Additionally, modifications to the part itself were examined to achieve the best results.

1. The problem-solving process using Moldflow simulations took several days and cost hundreds of euros.
2. With Moldflow simulations, we prevented future problems with the mold and part quality during the design phase.
3. No additional modifications were needed on the finished mold, which reduced the costs of bringing the part into production.