AlliedSignal Automotive

Premier manufacturer of automotive turbochargers meets an "impossible" deadline, designs complex engine manifold, and boosts the confidence of a valuable customer with the power of solid imaging.

The Challenge
AlliedSignal Automotive had just received a new contract for an elaborate design on a combined exhaust manifold/turbocharger with a close-coupled catalyst from a major automobile manufacturer. The project called for proof-of-production in an impossibly tight schedule: first units were scheduled for delivery in 40 weeks.

Since castings for the manifold turbine would be the controlling item for the product development cycle, castings would have to be completed in eight months, and casting tools in less than seven months. Given inevitable design changes, there appeared to be no way to use traditional machining methods without risking the success of the project.

AlliedSignal had to reduce its model-making time by a large margin to get a model in the hands of its customer on time and within budget. The company decided to explore a technology that had been suggested to them by a reliable toolmaker – stereolithography (SL).

The Results
AlliedSignal located a nearby service bureau and, utilizing SL, readily produced the required casting tools within seven months. High-quality castings were poured on time and the customer's project schedule was met in 39 weeks. Tony Birch maintains "there is a high probability to use SL again," because of its ability to:

• Evaluate machining of housing and unit assembly methods
• Visualize split line positions and block core assembly
• Cast, machine and assemble parts far in advance of conventional methods
• Achieve target dates and reduce project costs

The Process
After experimenting with several electronic routes, CATIA to IGES to SL, then CATIA to IGES to .STL to SL, AlliedSignal learned the best design path was CATIA direct to .STL to the SLA® system. Working within the 250 mm x 250 mm x 250 mm (10 in x 10 x 10 in) space of the material vat, the company built the SL model in three separate pieces, with casting-metal material shrinkage values included.

To expand the design, additional pieces were added, such as bosses, webs and fillets, and then the model was sanded down to shape and bonded together on a fixture plate to ensure stability. The turbine housing section was pinned and screwed to the manifold sections at the toolmaker's, a prototype feature which helped with the production of the block mold tools because it could be removed on demand.

A second 1:1 scale model was built and presented to the customer, enabling the customer to actually install it onto his engine cylinder block for accurate form, fit and clearance analysis. Clearance space around the engine was extremely tight, less than 10-12 millimeters at some points. Once fit was verified, the foundry was able to begin the "extremely difficult" casting process, using the model to determine optimum gate positions and split lines. The toolmaker was able to produce an LS material pattern top half and block mold tools for the bottom half of the housing.

The Tools
• IBM CATIA 3-D CAD system
• Use of SL service bureau in Gloucester and an SLA 250 system

Company Profile
AlliedSignal Automotive is the leading manufacturer of turbochargers in the world both for automotive and commercial applications. It has manufacturing facilities in France, Spain, Italy, United Kingdom and Germany. The company employs approximately 107,000 employees worldwide and invests over U.S. $600 million annually to develop and improve its technologies, products and processes.

AlliedSignal, Inc. is one of the world's premier industrial companies with operations in multiple markets: aerospace, automotive and engineered materials.