Smart car project illustrates merits of SLS

3T RPD and Taeno product development have completed an innovative project to demonstrate the capability of prototype components built using state-of-the-art selective laser sintering technology.

3T RPD, in collaboration with Taeno product development, has undertaken an innovative project to demonstrate the capability of prototype components built using state-of-the-art selective laser sintering (SLS) technology.

The majority of projects worked on by 3T are subject to its clients' confidentiality restrictions, so in order to increase the database of knowledge surrounding its SLS technology and the functionality of their prototypes, 3T purchased a Smart car in early 2004 with the intention of replicating or redesigning components, rebuilding them in SLS and testing them in true working environments.

The project began conventionally, with designers from Taeno submitting a range of rendered sketches of a redesigned front end.

Due to the reverse engineering aspect of the project, 3T asked 3D Scanners to digitise the front of the car to provide a digital surface that could be read into SolidWorks.

Once a final design was decided on, Taeno created a 3D CAD model which was then supplied to 3T for SLS components to be built.

The chosen design was intended as a contemporary update of the Smart car approach, and included separate front wings to mirror the construction method used on the back of the car.

The ability of the Smart car's body panels to be completely removed and replaced within four hours allowed access to the chassis fixtures and fittings, which gave fixed anchor points for the final design.

Critical components such as the door pillars and bumper fixtures had to be considered, and the windscreen washer and brake fluid reservoirs had to remain accessible to ensure the car's performance wasn't compromised.

The first prototype of the new design was built in April 2004 and fitted to the car for extensive functional testing in real driving conditions.

It was taken to exhibitions and roadshows, and showcased at numerous customer sites.

The components remained intact on the car while being driven over 1600km in all conditions, including motorway speeds, along country roads and in a variety of weather.

The close working relationship between 3T and Taeno enabled the two companies to develop the project in just 20 days; from the initial briefing and concepts through to the completed design and finished SLS components being produced.

The consistency of design personnel and the ability to have face-to-face meetings is the preferred style for both companies - having to visit a client, pitch the idea, await feedback and then start the cycle again once modifications have been made, can be extremely time-consuming.

Modifications to the parts were easily made as the project progressed, and as the design evolved any issues raised were instantly rectified.

For example, after the first batch of road testing it was found that the corner edges of the front wings clipped the road slightly when the car was subject to body roll.

Tim Plunkett, CEO of 3T says: "Being able to modify a design and a prototype cohesively is something we always emphasise as being imperative when discussing new product developments with our clients as, in reality, several iterations can be required before the final design is produced".

A second iteration of the design was built and fitted onto the car in Autumn 2004, and further road testing carried out.

Again, over 1600km was put on the clock in a variety of road and weather conditions.

In overnight freezing temperatures during November and December the car was parked outside, with no detrimental affect to the SLS components.

3T's ability to build single piece parts up to 700 x 380 x 580mm reduces the need for joints and additional assembly and thereby increases their functionality.

Further, it has led to dramatic reductions in production lead-times.

"In today's environment, no-one seems prepared to wait more than three weeks irrespective of the size of the project", says Plunkett.

"Capacity is essential as many projects now contain 10s or 100s of parts".

However, the ability to produce larger, higher quality prototypes in a shorter time frame, but at a similar cost, can have a knock-on effect of raising customer's delivery expectations.

"If we deliver a finished model within a tight deadline, customers know our capabilities and this pushes up our own benchmark", says Plunkett.

"This can result in a higher expectation next time they place an order and, in some cases, we're expected to improve on the delivery date still further".

In parallel to the project with Taeno, 3T also offered students in the South East region the opportunity to design and develop a component on the Smart car for their final year design projects.

They were allowed to either redesign an existing component or develop something completely new.

As such, David Oswald, an HND mechanical engineering student from Newbury College, designed a centre console for the car as it didn't incorporate one in its existing design.

Students from the University of Portsmouth also undertook designs and modified the wing mirror, steering wheel, sun visor and boot box.

All the components were produced by 3T in SLS, and fitted to the car for demonstration purposes.

Plunkett summarises: "High-tech design software can provide photorealistic images ideal for the concept stages of product development".

"However, a physical prototype speeds up the approval process and can be used in functional testing, assembly trials, wind tunnels and marketing photography".

"This project has proven, beyond doubt, the capability of our SLS prototypes".

The project is ongoing with further modifications being made to the design and road testing being carried out.

The car is being taken to exhibitions and client sites so that the true functionality of the parts can be viewed firsthand.

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