When Tata Motors Chairman Ratan Tata inaugurated the new paint shop at Tata Motors’ Jamshedpur plant in March 2010, he was especially pleased. The project was one after the chairman’s own heart — it used a new, innovative and immensely environmental-friendly approach to the plant’s paint pre-treatment process by using nanotechnology.
Not only did the new process cut down energy use and water consumption, it also reduced the generation of highly toxic effluent sludge that is a severe health hazard. The positive environmental effect of the new pre-treatment process is so high that it has won the Tata Innovista Promising Innovation award.
The project started three years ago when Tata Motors Jamshedpur needed a new paint shop for its truck chassis long members (there are different paint shops for long members, cross members, cab body, etc). The painting process for the metal parts of trucks and other vehicles is always an elaborate process. These metal members need to go through pre-treatment stages before they can be painted; this is to make them more resistant to corrosion and to improve the adhesion of primer and paint.
The electro-coat pre-treatment technology that Tata Motors follows at all its plants, including the Jamshedpur long member paint shop, is a state-of-the art cathode electrode deposition (CED) process that is being used by top auto manufacturers the world over. The metal parts undergo several stages, the most critical ones being those of activation and phosphating, in which the long members are immersed in hot baths that use vast quantities of water, titanium salts and chemical compounds containing zinc, nickel and manganese.
Though this pre-treatment process is a high-technology affair that ensures a quality product, it has several disadvantages. The biggest is the effluent generated by the plant in the form of a sludge that contains heavy metals (such as nickel). This sludge is toxic and extremely hazardous. Treating the sludge according to environmental norms requires installing several pieces of equipment, namely a clarifier, a filter press and an incinerator. The incinerator discharges smoke, causing air pollution. The solids left over are toxic and have to be stored in a secured landfill that takes up space at the plant site. The secured landfill itself is another potential biohazard as any seepage will result in land and groundwater contamination.
At Jamshedpur there was an added concern: the landfill area was nearly full. The company had to find a new site, thus making more land redundant as well as adding to the risk of pollution. Another environmental issue was the use of vast baths that needed as much as 60,000 litres of clean water and tonnes of fuel for heating. This water is heavily polluted and has to be treated intensely before it can be discharged.
All in all, however efficient the CED process, there was no gainsaying that it had a huge environmental impact. Three years ago, when Tata Motors needed a new paint shop, the project team in charge of setting up the shop decided to take a fresh look at pre-treatment technologies. “The climate change initiative is being taken seriously in the company. We are also very conscious of environmental concerns. We wanted to find a better, cleaner way of handling the pre-treatment process,” says team member NDS Murty, assistant general manager (central planning) at Tata Motors.
Research showed that there was an alternative to the pre-treatment process, one that was being used globally on aluminium and alloy surfaces. This is a nanotechnology process that uses a bath of zirconium oxide instead of conventional heavy metals. The team, a cross-functional one with members from quality assurance and planning, decided that the option had merit. It then started interacting with chemical suppliers to find a variant of zirconium oxide that would work on the mild steel used for truck components.
The chemical solutions underwent several stages of R&D and testing jointly carried out by Tata Motors and the chemical supplier Henkle Surface Coatings. After one year of intense testing the team came up with a zirconium compound (called Tectalis 5800T) that worked as well on hot-rolled steel as it did on aluminium. In the lab, the metal coating withstood all possible tests. “When we told the senior management about the nanotechnology results, they were very supportive,” says team member Vikram Khanna, manager, central planning.
The nanotechnology process has several advantages over the conventional method: it uses less energy, water and chemicals; it reduces water and air pollution drastically and, most significantly, it generates no toxic sludge, saving the company the need to invest in a new landfill. The waste products from the new process are useful iron hydroxides, which are a raw-material input for the pigment industry. As an added benefit, there is also a saving in natural resources; the new process uses far less material — just 60-120mg as opposed to the earlier 2,000-3,000mg — to give the same coating effect.
Risk and reputation
In spite of all the advantages, the team was conscious that the new technology was novel; they decided to play it safe. The compound was tested rigorously by BASF, the German company, to provide third-party validation. All in all, the new nanotechnology method was tested for two years. “We could not take any risk at all,” says project leader Vinay Kumar, senior manager, quality assurance. The paint shop costs about Rs630 million and twelve months to set up. Even more critically, if the shop did not perform to standards it would result in a shutdown of the entire truck assembly line for three months, an immense loss in terms of revenue and materials.”
When the deadline for setting up the paint shop came around, the team decided to further mitigate the risk by setting up the new pre-treatment shop in such a way that it could be converted back to the old technology in a short time. Even the major equipment such as filter press, heat exchanger, aqua therm heater etc — were bought and kept as a ready backup. “After all, this was the first time the process was being used in Asia,” explains team member Ashok Bareja, senior manager (central planning).
Though the team and the plant management were slightly anxious, the changeover turned out to be a smooth success. Today the new nanotechnology pre-treatment is running smoothly and already revealing its advantages. The paint shop’s consumption of diesel has been reduced by 300,000 litres; its carbon dioxide emissions have come down by 900 tonnes per annum; the water usage is lower by 800,000 litres; and the risk to human health, flora and fauna is dramatically lesser. “This is a far superior method. We are now trying to make it work on cold-rolled sheets,” says team member and quality assurance officer Arijit Das.
The success of the project is also visible in its impact across the rest of Tata Motors, given that the new process has already been finalised for the new cross-member paint shop and is being tested at nine other paint shops at different plants. With more changeovers on the cards, Tata Motors’ commitment to the environment will be reaffirmed with every vehicle that rolls out of its gates.