Rapid development of components for Volvo

Åse Dragland
Photo: VOLVO

SINTEF has become the 'purveyor to the Court' of complicated motorcar engine prototypes for the Volvo Car Company.

Magnus Gustavsson at Volvo is testing the gas flow in the motor.

By means of methods designed for rapid production it is possible to produce components with complex designs that are first produced in plastic before being cast in aluminium. The reduction in production time offered by this process is important in the race against competitors. The gas flow in a car engine is decisive for its efficiency. The way in which petrol fumes are sucked in through the manifolds and enter the engine, influences both the amount of fuel used and also the car's performance. The researchers who are in charge of engine development at Volvo want to be able to test the effect of manifold-design changes on gas-intake conditions in the car engine. To be able to measure the gas-flow in the manifolds, the Swedes must be able to rely upon the test components being exact replicas of the theoretical models that have been designed on the computer screen.

This is what the Department of Production Engineering at SINTEF Industrial Management is assisting Volvo with. Together with Volvo the researchers at SINTEF have introduced a brand-new production process in order to create accurate and complex flow boxes that is, exact replicas of the combustion chambers and intake manifolds in a cylinder head.

A week instead of two months

The technology behind all this is called 'Rapid Prototyping' or time-reducing engineering technology, and it is all about the rapid manufacture of three-dimensional prototypes. Digital 3D computer models are transferred to a file, and with the help of a Cubital machine at SINTEF, complicated details can be used as the basis for constructing accurate models from plastic material.

In the past these flow boxes were produced by means of computer-operated milling machines a time-consuming and costly process. The change to 'Rapid Prototyping' has meant that the time needed to produce a complex working model has been reduced from two months to one week. ''We have established a computer link between SINTEF and Volvo PV in Gothenburg by means of which the Swedes can provide us with access to files containing information about computer models. As soon as the Volvo engineer has finished the design work on the model we can retrieve it, and produce flow boxes which match the specifications exactly, and which can be returned to Volvo for testing within a week. Thus the people developing new engines at Volvo can complete their tests more quickly and are able to implement modifications within a reasonable time'', explains Nils A. Ruud at SINTEF Technology Management.

''The combination of this procedure with Volvo's own technical analyses of the gas-flow makes it possible to reach the theoretical point of digital design more quickly, safely and cheaply''.

International collaboration

The collaboration with Volvo started in 1994 after Ruud had been to Sweden in order to outline these new methods and the possibility of producing test details by means of decentralized team production. The construction of prototypes represents a bottleneck for everyone connected with the development of new products.

Development engineer Magnus Gustavsson at Volvo PV's section for combustion systems was interested straight away, and was able to perceive the potential benefits of such a collaboration across national borders. Today he is SINTEF's most important contact person within this field for Volvo.

''We chose to collaborate with SINTEF because they were the first to market their services in an aggressive way. A rapid response from researchers provides us with a definite advantage, and it is not easy to get one's hands on a modern Cubital machine in Sweden. Another plus is that we have managed to establish an efficient and timesaving computer link via the Internet'', says Gustavsson.

Prototypes of an intake manifold in aluminium and plastic.

Interdisciplinary

As the plastic test models cannot be used in actual car engines, Volvo has also had to be able to progress from digital descriptions and plastic models to cast aluminium and magnesium components. By means of collaboration with the Department for Casting and Metal Forming at SINTEF Materials Technology, researchers have developed a method which is based on 'Rapid Prototyping' to sandcast complex components in aluminium or magnesium, and to execute the modifications which are required in order to improve the technical casting design and dimensions of production runs and supply systems.

''On occasions we simulate the casting and hardening process before we build the actual model. In this way we are able to check our calculations and the modifications that have been implemented. When each detail is ready, the finished model technically up to specification so far as casting details are concerned is produced with the help of the Cubital machine. These models will in turn form the basis for the production of precision moulds made from hardened sand'', says Arne Nordmark at SINTEF Materials Technology.

''We can cast an intake manifold in aluminium and deliver it 3 to 4 weeks after we have received the computer specifications from Volvo. The manifolds are then ready to be mounted in the engine'', says Nordmark.

Volvo's engineers are very pleased with this interdisciplinary collaboration:

''In Sweden we would have needed two collaborating partners, a foundry and a company responsible for producing the prototypes. SINTEF is able to provide us with both because of this interdisciplinary co-operation'', says Magnus Gustavsson. ''Later this year we will try to produce aluminium cylinder heads along with SINTEF. This will mean data transfer of a different type from what we are engaged in today, but we have already started and we are convinced that we will succeed''.