Holset Engineering Co Ltd, a division of Cummins Engine Co., has been working with Castings Technology International over the past two years to refine new designs of turbocharger turbine housings for diesel engine applications.
The company’s aim was a reduction in lead times through an improvement in the castability. This partnership with Castings Technology International is contributing to the company’s overall strategy to build a World Centre of Excellence for Engineering at its Huddersfield site. A significant element of this strategy is to aim for continuous improvement in the integral quality of all its components.
The work on the turbine housings has involved a partnership between Holset (engineering and manufacturing), Castings Technology International, Vanguard Foundry and Triplex Williams, Hockley Pattern & Tool Co. and Coley & Wilkes Ltd. All parties have worked together to optimise designs and shorten lead times and this has given Holset the capability to move to full scale production in less than 2 months, with full confidence in the quality of the product. 3-D models of casting geometries, created by Holset’s design engineers using Pro-Engineer, are transferred electronically to Castings Technology International. There, engineers in the Design Centre, interrogate the component geometry using MAGMAsoft to identify thermal hot spots – points where defects are likely to arise. Subtle but critical modifications to the external component geometry may be required and, after further liaison with the foundry concerned, the gating andfeeding system refined before the product and its method of manufacture are fully optimised.
The capability of MAGMAsoft and the experience of its operators are crucial factors in achieving the high level of confidence necessary in this approach, because the patternmakers are simultaneously creating the coreboxes for the components. The power of the software and the competence of the MAGMAsoft engineers allows them to keep ahead of the patternmakers, to whom the external geometry modifications are sent electronically,in good time for them to generate cutter paths for CNC machining of the patterns.
Once the tooling is complete, prototypes are manufactured at the foundries, which have been involved in the project from the start. They have also received the component geometry electronically and have added core box and pattern requirements, such as clearances, split lines,and contraction.
Castings Technology International makes itself familiar with the foundries’ manufacturing processes as minor variations in techniques can be critical. The sample castings are inspected at the foundry before being delivered to Holset to be subjected to their own in-house testing procedures.
So far, Castings Technology International has worked on several different turbine housings using this approach, helping to create products which are easier to manufacture. This allows Holset and its suppliers to move rapidly into high volume production with great confidence in the product quality.
This partnership has been of benefit to all concerned. A key factor in the adoption of this approach was Holset’s appreciation that components inadequately designed for ease of manufacture can present severe and unnecessary constraints on casting producers in their endeavour to meet customer needs. This followed from casting design courses run by Castings Technology International for Holset’s engineers. As a forward-looking company, Holset quicklyseized the opportunities that new technology provided, all of which was available from Castings Technology International.