Heunisch has been using MAGMASOFT® for years as part of its preventative quality management system, to ensure a timely analysis of casting layouts and possible defect sources.
For a grey iron exhaust manifold, concerns regarding critical air entrapment arose at an early stage. To avoid production problems, an optimization of the casting layout was required, for the first time using the new possibilities for autonomous design of experiments in MAGMASOFT® Rel. 5.3.
Massive cold box cores were planned to be used for the green sand casting of the 1 m long marine exhaust manifold. The Heunisch employees were aware that the combination of the low gas permeability of these cores together with a very short pouring time would most likely cause problems. Due to the poor venting conditions, the danger of air entrapment in the upper part of the casting, which would be filled last, was considerable. The anticipated scrap was to be avoided by engineering a robust casting layout before the start of production.
The problems were visualized through the simulation of mold filling with the original casting rigging. The results showed a strong tendency for significant air entrapment in three areas of the casting. To allow a better venting in these areas, it was decided to add small bars between the manifold and the enclosure near the problematic regions. Consider-ing production requirements, varia-tions with one to three bars varying in their positions and widths were analyzed.
Two requirements were set: the new layout had to provide sufficient venting in the critical upper area of the exhaust manifold and needed to ensure a high robustness of the quality regarding process variations. The Heunisch employees used the new possibilities of MAGMASOFT® 5.3 to autonomously investigate different variations and to identify the best compromise. The parametrization of the bars allowed for an easy change in their position, width and number. The resulting set of 27 variations was set up for autonomous simulation and evaluation by MAGMASOFT®.
To focus on a quantitative evaluation of the most relevant quality criteria, the experts defined an evaluation area covering the critical areas of the
exhaust manifold. Two objectives for the optimization were set:
1.) minimization of the local air pressure and
2.) minimization of the air contact in the areas of concern.
For a clear overview and assessment of the results of all the calculated variations, the Heunisch experts used a scatter diagram. In this diagram, the different bar configurations were marked using colors and directly visualized regarding the defined optimization targets.
The best solutions, showing air entrapment below a defined limit, included two variations with two bars and one variation with three bars. The 3-bar-design also showed minimal air contact of the metal.
Compared to the initial design without the bars, the level of air entrapment was cut in half with this new layout. The castings eventually produced with the optimized 3-bar-design were within the specification, making the production of the exhaust manifold a technical and economic success right from the start.
Through this early optimization, the experts at Heunisch succeeded in finding a robust and qualitatively optimized solution before the start of production.
About Heunisch: Premium castings are tradition and the basis for the success and growth of the company Heunisch-Guss, established in 1980 in Germany. Four production sites in Germany and the Czech Republic reliably supply customers with demanding, high-quality aluminum die castings as well as grey, ductile and compacted graphite iron castings. In addition, Heunisch is known as a dependable and competent partner, supporting its customers in problem solving at all times. The constant and continuing education of their employees guarantees the necessary technical qualifications and is complemented by continuous investments in the most modern technology, to remain highly competitive in the global market. Heunisch has been using MAGMASOFT® since 2007.
* Text and images courtesy of Heunisch-Guss, Germany