2012 Lightweighting Special: Maruti's weight loss drive pays off

With stringent emission norms pushing the drive towards lightweight passenger cars, market leader Maruti Suzuki India cannot be far behind in the race to make vehicles more fuel efficient.

Its latest volume model, the Ertiga MPV that has proved to be a winner with over 32,000 bookings in the first month, has achieved lightweighting by rigidity of the body frame through use of higher tensile steel in strategic sections of the body structure supported by reinforcements. This provides increased rigidity and strength and helps reduce overall body weight without compromising on safety.

“If the basic rigidity in the Ertiga had not been increased, the MPV would have been heavier,” says I V Rao, managing executive officer, engineering, who clarifies that the body material – high tensile steel used in the new Swift – has not been changed. The body shell constitutes around 30 percent of the weight of the vehicle and major reductions can be achieved in this area. However, work is taken up on all areas to derive maximum benefit from the weight reduction exercise.

The new Swift, although bigger than the outgoing Swift, is lighter by around 30kg. Maruti and Suzuki actively follow a philosophy of making their upcoming new models lighter compared to previous versions for which all lightweighting initiatives are undertaken jointly both in Japan and India. Maruti's R&D team at present constitutes about 1,100 engineers.

A special highlight of the new Swift and Dzire models are their multi-layered plastic fuel tanks that cut weight of the fuel tank by 3kg compared to their older versions but retain the strength of steel. Furthermore, the new Dzire also achieved light weight through trimming of its length and leveraging a lesser number of parts.

However, the regular steel fuel tank has been used in the Ertiga; Rao says that the plastic tank could not be harnessed due to a layout constraint in the recently launched MPV. It is believed that Maruti’s upcoming small car – the Cervo – which will roll out by the year-end will also not utilise the plastic fuel tank.

The lightweighting mantra has been in practive since long at the carmaker. In 2010-11, Maruti Suzuki engineers were successful in reducing the weight of the Alto's seats by more than 5kg. The weight of the batteries was also reduced by around 500 grams.

Interestingly, MSIL has a two-pronged strategy for weight reduction spawning optimisation of the existing parts in their current material or process condition through careful examination of the part function and its optimisation based on that function. This involves a continuous improvement exercise.

These strategies are meant to incorporate major changes in the weight of the parts/aggregates either by changing the material and processes or by complete redesign of the parts. Major weight reductions have been achieved by usage of plastic parts in engines and also by usage of high strength steel in body parts as in the case of the new models.

INTERVIEW WITH I V RAO, MANAGING EXECUTIVE OFFICER, ENGINEERING, MSIL



What are the challenges in adopting technologies that help in weight reduction?

The single most important challenge in adopting new technologies for cost reduction is that many new technologies come at a higher cost. Hence, creating a balance between cost and weight is one of the biggest challenges for our engineers and managers.

How does Maruti Suzuki work in sync with vendors to introduce new ideas for weight reduction?

Benchmarking is one of the processes which MSIL uses for understanding the potential of weight reduction. It also encourages its vendors to adopt such techniques.

Also, specific programmes are conducted with vendors for optimisation of certain selected parts in a joint exercise of the engineering team of MSIL and the team from the vendor’s end.

Are engineering plastics the only cost-effective answer to steel?

There are various lightweight materials that are in the development phase and some are also implemented in high-end vehicles.

Their cost limits their usage in the kind of vehicles which are made in India for a value-seeking customer. Indian vehicles have still not explored the full potential of high strength steels and plastics. Once all these options are exhausted, it would be prudent to look at other materials for weight reduction.

How much of your R&D expenditure is spent on light weighting efforts?

Every project that MSIL undertakes today has a weight target associated with it. This is one of the areas for improvement of fuel consumption of vehicles that has been MSIL’s focus always.

Have you implemented any innovative ideas to enable lightweight manufacturing?

We have got a completely new plant set up by one of our supplier partners for manufacturing of plastic fuel tanks. At the same time, for implementation of high-strength steel material in body parts, we have encouraged suppliers to use cost-effective die manufacturing techniques.

Where do Indian OEMs rank when it comes to lightweighting efforts?

The average weight of an Indian vehicle is lighter than Japanese and European vehicles. This is mainly due to the small car fleet of India. At the same time, on a like-to-like basis, many of our vehicles are lighter than the European vehicles in the same category.

Much has already been done to keep the weight of the vehicles in control. Having low initial weight and working in a very value-conscious market brings with it the difficulties in reducing weight at a high rate. However, with ever increasing fuel efficiency targets, weight reduction will have a very big role to play. This has been seen already in some SUVs as well, which have shifted from ladder frame construction to monocoque construction to reduce weight.

SHOBHA MATHUR