by clicking the arrows at the side of the page, or by using the toolbar.
by clicking anywhere on the page.
by dragging the page around when zoomed in.
by clicking anywhere on the page when zoomed in.
web sites or send emails by clicking on hyperlinks.
Email this page to a friend
Search this issue
Index - jump to page or section
Archive - view past issues
button in toolbar for more information.
Metal Casting Technologies : June 2007
28 www.metals.rala.com.au CASE STUDY t the end of the seventies of the past century, engine blocks were for the first time no longer made from gray cast iron, but aluminum. This change in the raw material was triggered by the weight reductions allowed by the appreciably lower density of aluminum -- despite the higher material cost. Ever since, light metals such as aluminum and increasingly also magnesium are playing an ever more important role in engine construction. Not least, evermore stringent environmental protection laws also favor the use of light metals. 2006 was the first year that more passenger cars left European assembly lines with engine blocks of aluminum rather than gray cast iron. ADVANTAGES OF ALUMINUM DIE CASTING The engine block is made up of two distinct functional units -- the cylinder block (upper part housing the cylinders) and the crankcase (lower part housing the crankshaft). The die casting process has been found to be a very viable option for manufacturing aluminum engine blocks. It is distinguished by high output and flexibility in component design. The attractiveness of the die casting process is likely to increase further still, for the potential of aluminum as an engineering material has by no means been exhausted yet, at least in the field of Otto engines. Stateoftheart die casting machines equipped with cutting- edge realtime control systems allow highly variable selection and adjustment of the die cavity filling process. In addition, with the support of vacuum, they even permit heat treatment for increasing the strength of the components made. IN QUEST OF ADDITIONAL IMPROVEMENTS Aware of the attractiveness of die casting, the specialists at Bühler Druckguss (the Die Casting division of the Buhler Group) teamed up with their colleagues at the German die- maker Schaufler Tooling to find additional improvements. The goal that the project team set itself was to eliminate the still perceptible drawbacks of conventional manufacture. Ultimately, this would further increase the profitability of the die casting process for making engine blocks. In an initial analysis, the following cost drivers were identified and dealt with: • Long cycle times • Large and heavy dies • High wear on the cooling water jacket inserts • Long downtimes due to - timeconsuming die maintenance (for example tedious removal of the moving die half for changing the water jacket) - frequent injection of molten metal behind core slide guides - frequent die leakage - frequent rupturing of ejector pins - uncontrolled die heating and cooling Based on this analysis and Buhler's and Schaufler Tooling's experience, two new costoptimized engine block concepts were developed for making inline and Vengines. This effort was supported by the vast experience that Buhler has accumulated in the supply of over 30 die casting cells for making engine blocks, and that of Schaufler Tooling, which to date has supplied a number of engine block dies. Both concepts have now been patented. DIEMAKING AND MECHANICAL ENGINEERING BLENDED The difference between an inline engine and a Vengine lies in the configuration of the cylinders. As the name suggests, the cylinders of an inline engine are arranged in a straight row, whereas two cylinder rows are arranged in a Vshape at a certain angle in the Vengine. The revolutionary thing about the two new Buhler concepts is that they are the first to blend cuttingedge diemaking with stateoftheart mechanical engineering technology. This combination of the two disciplines produces a commercially promising solution for manufacturing engine blocks. Thus, for instance, the water jacket and the contour core slide can be pulled by a certain stroke length already after partial solidification of the metal. This reduces the heat input from the aluminum into the water jacket, which in turn appreciably increases the life cycle of the water jacket. Blending Die Casting with Die Making A The Buhler Die Casting division and Schaufler Tooling have introduced a new concept for manufacturing engine blocks by the die casting process. New, patented die casting tool concept for making Vengines.