Heller meets CGI block machining challenge

Although Compacted Graphite Iron (CGI) has been known to metallurgists for many years, it has only recently become interesting to the automotive manufacturers. Used for the manufacture of engine blocks and heads, compared with traditional grey cast iron it offers advantages such as more power and longer intervals between maintenance, reduced weight, less pollution and diminished noise. However, it also presents a complete change to the manufacturing processes applied, since significantly different tools are required for this material. The Heller devised manufacturing system, based on existing facilities, combines four dedicated machine lines to provide specific machining of critical features with 18 direct-loaded MCH 400 horizontal machining centres. Heller also integrated an Alfing cracking system for the crankshaft bearing caps, lift and carry systems, linear loaders and overhead gantry loaders for material handling and washing machines as well as the tooling package. Pre-machining of the main features of the crankcase, which is manufactured from CGI 450, includes machining the cylinder head and sump face joint faces, cylinder and crankshaft bores, all of which is completed on two of the dedicated machining lines. Single spindle machining with automatic tool changers and turret heads were used on individual stations. The system also comprised deep hole drilling and pre-machining of the crankshaft bore. A special feature of the system is a TBT gun drilling unit and head changer in the third dedicated machine line. The final section in the manufacturing line is used for finished machining of numerous sealing faces, the crankshaft and cylinder bores, and the cylinder head joint face. Within the manufacturing line machining operations are monitored via in-process gauging. In addition to developing and installing the manufacturing system for the D20 crankcases, Heller also took full responsibility for planning and commissioning the manufacturing process for the other key components of the engine. The cylinder head is manufactured using 10 Heller MCP-H 400 horizontal machining centres and 4 HCS 400 head changers integrated into an automated line. The latest generation of Heller’s internal milling machines is employed for crankshaft machining. The machines of the RFK 400 (300) range provide excellent quality in the machining of mains and pins. The D20 engine has a 25 per cent reduction in engine components and a weight reduction of 100 kg, meets significantly reduced emissions standards, extends maintenance intervals to 120,000 km and cuts fuel consumption by more than 5 per cent. Heller Machine Tools managing director, Geoff Lloyd said: “The project has been an exciting venture for both companies, and a highly successful one. By combining state-of-the art materials, engine design, production machines and methods a highly successful new-generation of heavy engines for commercial use has been created. It has utilised Heller’s core competences to their full advantage and is a perfect example of the way in which Heller can bring to fruition a project in a previously untried field”.