Due to their low thermal conductivity and high thermal expansion, austenitic chromium‐nickel steels have an increased tendency to distortion during welding. In industrial sectors such as rail vehicle construction, there is a high demand for geometrical precision that is not met by distorted components. Introducing a low transformation temperature (LTT) effect in the weld seam influences the stress distribution, which effects the formation of welding distortion. The low transformation temperature effect is achieved by in situ alloying using commercially available materials. The demonstrators made of stainless steel (X2CrNiN18‐7/1.4318) were welded with a low‐alloy filler metal G4Si1. The low transformation temperature effect is assessed by energy dispersive x‐ray spectroscopy and hardness measurements. The effect on distortion was investigated by measuring the demonstrators with a coordinate measuring system and the results were compared with the reference stainless steel demonstrators with stainless filler metal. The alloying process resulted in a reduction of the alloy content to 14.4 m% chromium and 5 m% nickel and a medium‐high hardness of 361 HV 0.2 to 383 HV 0.2. The low transformation temperature effect achieved leads to a significant reduction in welding distortion of up to 78 % compared to the similar reference demonstrators.

Dimensional accuracy is a highly important quality criterion for injection molded parts and due to the decreasing tolerance criteria an ongoing issue for mold makers, part designers and manufacturers. Variations in the molding process regarding temperature, pressure and thus the specific volume are leading to inner stress distributions within the part, which ultimately cause warpage. To reduce warpage, a homogenization of the local melt properties, such as the temperature, cooling rate or specific volume is necessary. To be able to manipulate these melt properties locally, a mold with a highly segmented temperature control, consisting of 18 heating ceramics and carbon dioxide expansion chambers was designed. This work seeks to reduce warpage using a newly developed control loop that adjusts target values for the upcoming molding cycle while considering the control error of the previous cycle. The self‐optimizing control loop‐ aiming to homogenize the local mold temperatures over multiple cycles‐ was evaluated in experimental trials. Test specimens were produced, and measured for warpage. Compared to the reference (no control), the warpage of a plate‐shaped geometry was reduced by 10 % with the mold temperature homogenization approach.

The injection mold is one of the most important elements for the part precision of this important mass production process. The thermal mold design is realized by cooling channels around the cavity and poses as a decisive factor for the part quality. Thus, the objective but specific design of the cooling channel layout is crucial for a reproducible part with high-dimensional accuracy in production. Consequently, knowledge-based and automated methods are used to create the optimal heat management in the mold. One of these methods is the inverse thermal mold design, which uses a specific calculation space. The geometric boundary conditions of the optimization algorithm influence the resulting thermal balance within the mold. As the calculation area in the form of an offset around the molded part is one of these boundary conditions, its influence on the optimization result is determined. The thermal optimizations show a dependency on different offset shapes due to the offset thickness and coalescence of concave geometries. An algorithm is developed to generate an offset for this thermal mold design methodology considering the identified influences. Hence, a reproducible and adaptive offset is generated automatically for a complex geometry, and the quality function result improves by 43% in this example.

Foam injection moulding (FIM) enables lightweight thermoplastic parts, but current process simulations do not resolve microstructure formation. This work presents a micro-scale CFD framework for FIM that captures gas–melt interaction and bubble morphology. A two-phase, compressible volume-of-fluid solver (OpenFOAM) with surface tension and viscoelastic Phan–Thien–Tanner rheology is coupled to a nucleation pre-processor based on classical nucleation theory, which places bubbles stochastically using macro-scale pressure and temperature histories. The approach was demonstrated on a plate geometry using a 2D through-thickness section to investigate bubble nucleation, deformation, coalescence, and interaction under realistic process conditions. The simulations reproduced characteristic morphology trends across the thickness. In particular, the predicted aspect ratio and orientation show the expected skin–core behaviour and agree qualitatively with experimental observations. These results demonstrate that the framework can describe morphology development beyond simplified spherical-cell assumptions and provides a proof of concept for multiscale coupling between macro-scale process conditions and micro-scale foam structure evolution. A simplified surrogate growth representation was used to enable bubble expansion; however, a physically based mass-transfer model is required for quantitatively accurate growth kinetics.

The thermal balance of injection molds is defined by the cooling channel layout. However, the fluid tempering of injection molds underlies certain restrictions concerning the thermal dynamic and the local limitation of the zone of influence. The optimal heat balance within the mold to minimize warpage cannot be solely achieved with conformal cooling channels. Ceramic heating coating systems applied by Thermal Spraying on the cavity wall are a novel tempering method for high heating rates and offer the possibility of a more local heat input. In terms of the thermal mold design, the position and size of local heating coating systems need to be determined. A methodology is proposed, which connects the optimization of part warpage by defining the necessary local heat flux within the mold with the determination of the heating coating placement. Due to the dependence of the coating placement on the heating time and the power, different decision criteria of these parameters are discussed with regard to the process efficiency. The developed methodology can calculate the necessary heating power distribution to homogenize the surface temperature and freeze time. A second step discretizes the heating power distribution to certain manufacturable heating zones.